Bar Morphology As a Function of Wavelength: � a Local Reference for High-Z Studies

Bar morphology as a function of wavelength: a Local Reference For High-z Studies

Karín Menéndez-Delmestre Observatório do Valongo Universidade Federal do Rio de Janeiro Kartik Sheth (NRAO), Tomás Düringer (Valongo), Cameron Charness (UVA) & the S4G Team

S4G Core: Armando Gil de Paz, Joannah Hinz, Juan Carlos Muñoz- Spitzer Survey of Stellar Mateos, Mike Regan, Mark Seibert, KMD, KS Structure in Galaxies

Why do we care about bars?

Disks like forming bars! – A galaxy disk will naturally form a bar in a couple of Gyrs unless it is dynamically hot or is dominated by dark maer (Athanassoula+)

à The presence of a bar allows us to gauge disk “maturity”

Bars transform their hosts! • The gas transport triggered by a bar can aﬀect signiﬁcantly its host à (Marn & Roy 2004; wash out metallicity gradient across galaxy but Sánchez-Blázquez+11) à central accumulaon of molecular gas (e.g., Sheth+05) à triggering nuclear starbursts

à leading to the formaon of pseudobulges (e.g., Kormendy & Kennicu 04) à perhaps even feeding an AGN

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre Morphological classiﬁcation of local galaxies – it all started in the optical… • Morphological classiﬁcaon of galaxies in the opcal à ~2/3 of spirals are barred (de Vaucouleurs+63)

NGC1300

NGC1068 2MASS, Large Galaxy Atlas APOD

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre Morphological classiﬁcation of local galaxies – look in the infrared! • Morphological classiﬁcaon of galaxies in the opcal à ~2/3 of spirals are barred (de Vaucouleurs+63) • Case studies in the IR showed bars unseen in the opcal – IR traces old, low-mass stars (e.g., Scoville+88)

– Bars are dominated by old stars

à Are all galaxies barred and we just need to look in the IR?

NGC1068 2MASS, Large Galaxy Atlas

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre The quest for the bar fraction

• The Two-Micron All-Sky Survey (2MASS; Skrutskie+05) – Large Galaxy Atlas (LGA; Jarre+03) • > 500 large (~2’ to 2°) galaxies • J, H, Ks

• The bar fracon stays constant across

wavelengths from opcal to near-IR

(e.g., Menéndez-Delmestre+07)

– Why is this interesng? • We can trace the evoluon of the bar fracon with redshi (à disk maturity!), safe from band-shiing eﬀects!

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre 1148 SHETH ET AL. Vol. 675 Redshift Evolution of the Bar Fraction: Decreases beyond z~0.4 @ z=0: 65%

Fracon Bar

@ z=0.8: 15% [based on HST resrame opcal]

Sheth+08 Fig.Dissecng Galaxies Near & Far, Sanago 20156.—Comparison of measurements of our bar fraction with previous studies.Redshif bar and f SB measured using theKarín ElPa method Menéndez- for the COSMOSDelmestre data are shown with the black ﬁlled squares and diamonds respectively. The red data circles (13/30 bars in low z bin, 4/14 in the high-z bin) are from Abraham et al. (1999); these do not distinguish between weak and strong bars. Purple triangles are bars and twists from Elmegreen et al. (2004) (10/34, 13/90, 13/35 bars, respectively);wesummedadjacent bins from their data; they suggested inclination and resolution effects should increase the fractions by about a factor of 2. The green points from Jogee et al. (2004) are the strong bar fractions from GEMS; the three points in the two redshift bins are not independent of each other—they are measured for 110 Y175 galaxies, chosen in different ways from the same sample. The horizontal bars show the redshift range over which these data are averaged. Also shown are data from our analysis of a SDSS control sample (square—fbar,diamond—fSB), and from the 2MASS survey by Mene´ndez-Delmestre et al. (2007) (blue diamond is when both ellipticity and position angle signatures are present, whereas the square also includes candidate bars. The vertical dotted line is the limiting redshift for our survey. Within the error bars all the data seem to be in agreement. Contrary to earlier interpretations, it seems that all studies show a general decline in the bar fraction with redshift. It is only with the COSMOS data that we are able to analyze this decline in detail.

(Shen & Sellwood 2004; Athanassoula et al. 2005). Neverthe- Simulations show that interactions speed up bar formation less, it is by no means clear that this mechanism is unimportant. in direct encounters, but have little effect in retrograde ones We have so far discussed only isolated galaxies. Let us now (Toomre & Toomre 1972; Noguchi 1987; Gerin et al. 1990; turn to the effect of interactions and mergings. The number of Steinmetz & Navarro 2002), in good agreement with observa- interactions are known to increase dramatically with redshift tions (Kormendy & Norman 1979; Elmegreen & Elmegreen (e.g., Kartaltepe et al. 2007 and references therein). Interactions 1982). Thus one might have expected higher rates of bar forma- and merging activity are most likely to influence (heat up) the tion at high z, where interactions are common. On the contrary, it less massive galaxies. It is precisely in such galaxies that we see is possible for mergings to destroy or severely weaken the bar, significantly lower bar fractions compared to the high-mass gal- without destroying the disk (e.g., Berentzen et al. 2004 and ref- axies at the highest redshifts (Figs. 3 and 4). Although indirect, erences therein). More modeling needs to be done before we can there is observational evidence that later type and less massive say with any certainty what the combined effect of interactions systems are dynamically hotter. The top row of panels in Figure 1 and mergings is. Note that we discarded from our statistics ob- of Kassin et al. (2007) clearly shows that late-type spirals and viously interacting systems based on tidal features or obvious irregulars have larger disordered motions compared to early-type distortions. However, if a galaxy is weakly interacting, it would spirals particularly at high redshifts. These are precisely the type be difficult to distinguish it from a noninteracting system; this of systems within which we find fewer bars. Moreover, in the is already the case even in the local universe. So our sample of same figure, the higher mass galaxies also have a higher fraction galaxies is most likely probing quiescent, postmerger or weakly of ordered motions than disordered motion, although the trend interacting disks. is hard to see in the relatively modest sample size in the high- 5.3. The Downsizin Si nature in Formation redshift bins. These data suggest that the lack of bars may there- g g of Galactic Structure fore be related to the dynamic hotness and the mass surface density of these disks. We are currently identifying bars and measuring Galaxy ‘‘downsizing’’ was coined by Cowie et al. (1996) to the bar fraction in this sample of galaxies and should be able to refer to an evolutionary history in which the most massive gal- provide a direct answer for the said hypothesis (Sheth et al. 2008). axies formed first. There is strong observational evidence for the The quest for bar characterization – do bars change over cosmic time?

• Band-shiing from near-IR to opcal does not hamper (signiﬁcantly) the ability to recognize bars à So we can trace the evoluon of the bar fracon based on the huge amount of high-resoluon opcal imaging available (HST) How about our ability to trace bar properes? • Several studies have looked at bar properes locally (e.g., Erwin+05+13, Laurikainen+07, Gado+08, Hoyle+11)

2MASS median bar: • abar = 4.2kpc • εbar=0.5 Menéndez-Delmestre+07

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre The quest for bar characterization – do bars change over cosmic time?

• Although some studies on bar properes have ventured to higher redshis (Barazza et al. 2009), band-shiing eﬀects on the bar

morphology have not been explored. (Qb: Spelncx+08)

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre

Bar Morphology at high z need a local reference to extend studies to high redshift

• Need to know how the bar properes change with wavelength!

We look at bar properes as a funcon of waveband in a sample of 16 local barred spirals with deep mul-band imaging from UV – opt –IR , based on GALEX, SINGS and S4G imaging.

NGC1097 31 3.6μm R B NUV FUV 31 Spitzer Survey of Stellar Structures in Galaxies Figura 12: Imagens de NGC 1097(PI nas bandas:Kark 3.6 µm Sheth (imagem a),) RKMD+14 (imagem b) B (imagem c), NUV (imagem d) e FUV (imagem e). As imagens est˜ao orientadas com o Norte para cima e Leste para esquerda. Legacy Survey of the Warm Spitzer Mission IRAC 3.6/4.5um of >2300 local galaxies http://s4g.caltech.edu Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre

Figura 12: Imagens de NGC 1097 nas bandas: 3.6 µm (imagem a), R (imagem b) B (imagem c), NUV (imagem d) e FUV (imagem e). As imagens est˜ao orientadas com o Norte para cima e Leste para esquerda. Bar Morphology at high z need a local reference to extend studies to high redshift

• Need to know how the bar properes change with wavelength! mid-IR: opmal window UV: explore band-shi out We look at bar properes as a funcon of waveband in a sample of 16 for stellar structure to z>0.8 local barred spirals with deep mul-band imaging from UV – opt –IR , based on GALEX, SINGS and S4G imaging.

NGC1097 31 3.6μm R B NUV FUV 31 Spitzer Survey of Stellar Structures in Galaxies Figura 12: Imagens de NGC 1097(PI nas bandas:Kark 3.6 µm Sheth (imagem a),) RKMD+14 (imagem b) B (imagem c), NUV (imagem d) e FUV (imagem e). As imagens est˜ao orientadas com o Norte para cima e Leste para esquerda. Legacy Survey of the Warm Spitzer Mission IRAC 3.6/4.5um of >2300 local galaxies Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre

NGC1566 εmax= εbar

SMAbar ~ 30” (3kpc)

PA ~ 0 • widely-used ellipse-ﬁt technique bar

Figura 14: Esquerda: Imagem da galáxia NGC 1566 no filtro 3.6 µm, ilustrando as elipses ajustadas por cima da galáxia. Note que, para fins de visualisa¸cão, a diferen¸caKMD+14 Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre entre o semi-eixo maior de duas elipses consecutivas éde 3 step (vide 3.2.1); § portanto apenas 1/3 das elipses ajustadas estão sendo representadas na figura. A Figura 14: Esquerdarelosu¸cãoespacial: Imagem e da o step galáxiadesta imagem NGC estão 1566 indicados no na filtro figura. 3.6Direitaµ:m, Perfis ilustrando de as elipses ajustadas porelipticidade cima e da de ângulo galáxia. de posi¸cão Note da que, mesma para galáxia. fins A assinatura de visualisa¸cão, da barra éclara a diferen¸ca neste caso: a elipticidade cresce continuamente atéatingir o máximo, seguido por entre o semi-eixo maior de duas elipses consecutivas éde 3 step (vide 3.2.1); uma queda abrupta. O comprimento da barra medido pelo método da elipticidade § portanto apenas 1/3máxima das para elipses esta galáxia ajustadas estáindicado estão pela seta. sendo Em alguns representadas casos tambémocorre na figura. A uma varia¸cão no ângulo de posi¸cão, após a elipticidade atingir o máximo, como éo relosu¸cãoespacialcaso e o dostep perfildesta de ângulo imagem de posi¸cãodesta estão galáxia. indicados na figura. Direita: Perfis de elipticidade e de ângulo de posi¸cão da mesma galáxia. A assinatura da barra éclara neste caso: a elipticidade cresce continuamente atéatingir o máximo, seguido por uma queda abrupta. O comprimento da barra medido pelo método da elipticidade máxima para esta galáxia estáindicado pela38 seta. Em alguns casos tambémocorre uma varia¸cão no ângulo de posi¸cão, após a elipticidade atingir o máximo, como éo caso do perfil de ângulo de posi¸cãodesta galáxia.

38 Bars properties: from optical through IR 3.6μm

• Based on SINGs ancillary B, R and S4G 3.6μm IRAC/Spitzer images • Angular resoluon ~1-2” Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre

Figura 21: Perfis de elipticidade,Figura 21: Perfis de varia¸cão elipticidade, varia¸cão da da elipticidade, elipticidade, ângulo de posi¸cão e ângulo va- de posi¸cão e varia¸cão do ângulo de posi¸cão e imagens com elipses superpostas de NGC 3049, se- ria¸cão do ângulo de posi¸cãoguindo e o formato imagens da figura 16. com elipses superpostas de NGC 3049, se- guindo o formato da figura 16. 50

50 3.6μm Bars properties: from UV through IR

NUV

• Including GALEX NUV [2267 Å] and FUV [1516 Å] – To address high-z (z>0.8) studies based on opcal imaging – Angular resoluon ~6” FUV

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre Figura 41: Perfis de elipticidade, varia¸cão da elipticidade, ângulo de posi¸cão e va- Figura 41: Perfis de elipticidade, varia¸cão da elipticidade, ângulo de posi¸cão e varia¸cão do ângulo de posi¸cãoria¸cão e imagens do ângulo de posi¸cão com e imagens elipses com elipses superpostas superpostas de NGC 3049, se- de NGC 3049, se- guindo o formato da figura 36. A barra nos filtros NUV e FUV não foram identifi- guindo o formato da figura 36.cadas pois A foi barra imposs´ıvel ajustar nos elipses filtros na maior parte NUV da galáxia e (sma FUV < 5000) não foram identifi-

72 cadas pois foi imposs´ıvel ajustar elipses na maior parte da gal´axia (sma < 5000)

72 1st result: NGC 4725 NGC 3627 NGC 3351

we lose bars in the UVrest

• We lose ~50% of all bars in the NUV/FUV bands

• Band shiing is an issue when going to shortwards of the Balmer break

à Studies of bars at high redshi – beware!

à HST data beyond z~0.8 traces emission bluewards of the Balmer break Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre

Figura 49: Perfis de elipticidade,Figura 44: varia¸cão Perfis de da elipticidade, elipticidade,Figura 43: varia¸cão ângulo Perfis de de da posi¸cão elipticidade, elipticidade, e va- varia¸cão ângulo de da posi¸cão elipticidade, e va- ângulo de posi¸cão e varia¸cão do ângulo de posi¸cãoria¸cão e imagens do ângulo com de elipses posi¸cãoria¸cão superpostas e imagens do ângulo comde de NGC elipses posi¸cão 4725, superpostas e se-imagens com de NGC elipses 3627, superpostas se- de NGC 3351, se- guindo o formato da figuraguindo 36. o formato da figuraguindo 36. o formato da figura 36.

80 75 74 2nd result: bars look thinner in bluer bands

• εmax is higher in the opcal bands, compared to the mid-IR

εband1/εband2 Figura 32: Histograma e gráfico de dispersão representando os valores medidos para Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 32: Histograma e gráfico de dispersão representando os valores medidos para aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

61 2nd result: bars look thinner in bluer bands

• εmax is higher in the opcal bands, compared to the mid-IR

εband1/εband2 > 1

àBar measured to be more ellipcal in the bluer band

ε /ε εband1band1/εband2band2 Figura 32: Histograma e gráfico de dispersão representando os valores medidos para Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 32: Histograma e gráfico de dispersão representando os valores medidos para aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

61 Figura 56: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

2nd result: bars lookFigura thinner 56: Histograma in bluer e gráficobands de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

• εmax is higher in the opcal bands, compared to the mid-IR • This result extends to the UV

εband1/εband2 Figura 57: Histograma e gráfico de dispersão representando os valores medidos para Figura 32: Histograma e gráfico de dispersão representando os valores medidos para Dissecng Galaxies Near & Far, Sanago 2015aelipticidadedabarrautilizandoométododaelipticidademáxima. Karín Menéndez-Delmestre aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 32: Histograma e gráfico de dispersão representando os valores85 medidos para aelipticidadedabarrautilizandoométododaelipticidademáxima.Figura 57: Histograma e gráfico de dispersão representando os valores medidos para aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

61 2nd result: bars look thinner in bluer bands

• εmax is higher in the opcal bands, compared to the mid-IR • This result extends to the UV

• Driven by bulge sizes: • Bulge looks bigger in redder bands à smaller in the blue - Limits the size of the bar Δεband-shiing ~15-20% thinner semi-minor axis : 0.07 (up to 0.14) : 0.07 (up to 0.15) à Bar looks thinner

Figura 32: Histograma e gráfico de dispersão representandoThe bluer os valores the medidosresrame para band, the thinner the bar! Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

61 Figura 32: Histograma e gráfico de dispersão representando os valores medidos para aelipticidadedabarrautilizandoométododaelipticidademáxima. Figura 32: Histograma e gráfico de dispersão representando os valores medidos para aelipticidadedabarrautilizandoométododaelipticidademáxima.

3rd result: bars look longer in bluer bands

• SMA where ε = εmax is larger in the opcal bands, compared to the mid-IR

aband1/aband2 Figura 33: Histograma e gráfico de dispersão representando os valores medidos para Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre ocomprimentodabarrautilizandoométododaelipticidademáxima.

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para 61 ocomprimentodabarrautilizandoométododaelipticidademáxima.

3rd result: bars look longer in bluer bands

• SMA where ε = εmax is larger in the opcal bands, compared to the mid-IR

aband1/aband2 > 1

àBar measured to be longer in the bluer band

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para 61 ocomprimentodabarrautilizandoométododaelipticidademáxima.

61 3rd result: bars look longer in bluer bands

This result also extends to UV

The bluer the resrame band, the longer the bar! Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre 3rd result: bars look longer in bluer bands

Star-forming knots at NUV the end of bars become more prominent and drive maximum ellipcity further out.

3.6um FUV

The bluer the resrame band, the longer the bar! Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre

Figura 37: Perfis de elipticidade, varia¸cão da elipticidade, ângulo de posi¸cão e varia¸cão do ângulo de posi¸cão e imagens com elipses superpostas de NGC 1097, se- guindo o formato da figura 36. As linhas pontilhada indicam regiões onde a rotina ellipse falhou e nãofoi poss´ıvel ajustas isofotas el´ıticas. O mesmo significado desta linha pontilhada vale para as figuras 39, 45 e 49. 68

3rd result: bars look longer in bluer bands

Δl_barband-shiing Bà3.6μm: 10% NUVàB: 10%

Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre Figura 33: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

61 Figura 32: Histograma e gráfico de dispersão representando os valores medidos para aelipticidadedabarrautilizandoométododaelipticidademáxima.

3rd result: bars look longer in bluer bands How signiﬁcant? Comparable to reported diﬀerences with respect to: • environment (e.g., Barazza+09) • AGN content (e.g., Laurikainen+02) • Hubble type (e.g., Menéndez-Delmestre+07)

Δl_barband-shiing Bà3.6μm: 10% NUVàB: 10%

61 Take away points… • As we extend bar studies out to high redshis, our single-band studies are inevitably subject to band-shiing eﬀects:

– We lose 50% of bars in the UV à need to sck to the red side of the Balmer break in order to reliably detect bars – Bars change in shape as we go bluer; even in the resrame opt: • Bars get thinner, due to apparent bulge size • Bars look longer, as star-forming knots become prominent – Need to consider this when comparing bar morphologies as a funcon of galaxy properes! – These band-shiing effects may affect the “ease” to detect bars • Refraining from going bluer than B-band may be good enough to study bar fracon out to z~0.8… but not bar properes! – Need to correct for band-shiing effects even in the opcal! Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre Take away points… • As we extend bar studies out to high redshis, our single-band studies are inevitably subject to band-shiing effects:

– We lose 50% of bars in the UV à need to sck to the red side of the Balmer break in order to reliably detect bars – Bars change in shape as we go bluer; even in the resrame opt: • Bars get thinner, due to Stay tunedapparent bulge size for • Bars look longer, as star-forming knots become prominent Bar properes at high-redshi! – Need to consider this when comparing bar morphologies as a funcon of galaxy properes! – These band-shiing effects may affect the “ease” to detect bars • Refraining from going bluer than B-band may be good enough to study bar fracon out to z~0.8… but not bar properes! – Need to correct for band-shiing effects even in the opcal! Dissecng Galaxies Near & Far, Sanago 2015 Karín Menéndez-Delmestre 1148 SHETH ET AL. Vol. 675

Fracon Bar

80 75 74 NGC 1512 NGC 1566 NGC 3198 NGC 3351 NGC 3627

NGC 4321 NGC 4579 NGC 4625 NGC 4725 NGC 5713 Figura 43: Perfis de elipticidade,Figura 44: Perfis varia¸cão de daelipticidade, elipticidade, varia¸cão ângulo da de elipticidade, posi¸cão e va- ângulo de posi¸cão e varia¸cão do ângulo de posi¸cão e imagens com elipses superpostas de NGC 3351, se- ria¸cão do ângulo de posi¸cão e imagens com elipses superpostas de NGC 3627, se- guindo o formato da figura 36. guindo o formato da figura 36.

74 75

Figura 49: Perfis de elipticidade, varia¸cão da elipticidade, ângulo de posi¸cão e varia¸cão do ângulo de posi¸cão e imagens com elipses superpostas de NGC 4725, se- guindo o formato da figura 36.

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%2*(0*4)*(3.T* 1#2#(*(+,'-)'2'$"$+3$"3!"44"5(!45/4)/2#+(/+5/(3*5#()/".)#(*([%/(/2(0*4)*+((/(#(+/2./.T#(2*.#-( B FUV KMD+14 2*.+(*B%.+(#(0#k#(A(2/4#+(,-#/2.4/45/(,#-(+/-( ,)* #4)/(/+5*(/$.,5.1.)*)/(A(*5.4K.)*(1#2#(#( Fracon ' • Band shiing is an issue 1#2,#+5#(,-.2*-.*2/45/(,#-(/+5-/$*+("/$F*+(/( when going to shortwards 386%%636!9+)':63;3)+%)"43%+3"%3 267-4'7+#)63$"3!"44" Bar of the Balmer break "/-2/$F*+e(4*+(0*4)*+(2*.+("/-2/$F*+(#( 9&6":"#&$'2&4%+,-",."##",4+,;<+3%+3 5&637%"-+6,&,!+4$7368&6/ Fig. 7.—Bar fraction as a functionSDSS of theband SDSS filters (u, g, r, i,andz) for a local sample of 139 SDSS galaxies. The left panel shows the results using the visual classification method and the right panel using the ellipse-fitting method described in 3. These are the same methods used for the analysis of the COSMOS data. The asterisksDAS Seminar (U. de Chile), March 19, 2014 show the total bar fraction and the diamonds show the strong bar fraction, as describedx in 3.Karín The pair Menéndez- of numbers aboveDelmestre each point are the-6%%"3":",'"43%<"3+:6,<=?63 total number of galaxies and bars identified by each method. The u-band data+ point is missing in the right panel because)/5/15*)*+()/".)#(*#(/3/.5#()/(2%)*4&*( thex ellipse-fitting algorithm fails in a majority of the galaxies in the u band. As noted in the text the main point of this exercise is to quantify the effects of k-correction on bar identification. We find that there is a significant k-correction for the bar fraction shortward of the Balmer break in the u band but the bar fraction is constant from the z band to the g band. '#)4@#%+2"33+73$'(+4+#)+%3)/(0*4)* APPENDIX A 4+$%&'()% (H(1#2,-.2/45#()*(0*--*(4'#("*-.*(2%.5#( ANALYSIS OF SELECTION EFFECTS (@A:DBCE (8/(\](K*$7T.*+(*4*$.+*)*+(".+%*$2/45/(4#(LJ=(3#-*2( Although we have carefully chosen a robust sample of galaxies, used multiple methods for identifying bars and analyzed a sample *5-*"A+()*+().3/-/45/+(0*4)*+ of local Sloan Digital Sky Survey (SDSS) galaxies in the same manner as the(!+5%)#+(2#+5-*2(%2*([%/)*()/(wàp( COSMOS galaxies ( 2), our results are in contradiction )/5/15*)*+(0*--*+(/2(n()/$*+(YòpZ to some previous studies. Therefore we do additional investigation of the remaining possible selectionx effects (cosmological/surface tub]aaa(v brightness dimming and spatial resolution), which might produce4*(3-*&'#()/(/+,.-*.+($#1*.+(1#2(0*--*+(4* a declining bar fraction. A1. K-CORRECTIONS()* AND THE EFFECTS OF BANDSHIFTING (Q(/$.,5.1.)*)/(A(2*.#-(/2(0*4)*+()/(2/4#-( The ACS data for COSMOS utilizes the broad F814W filter which traces different rest-frame wavelengths at different redshifts. As (!+5*+(n(K*$7T.*+(/+5'#(/45-/(*+(](K*$7T.*+(k7(*4*$.+*)*+( a result it is imperative to understand the effects of k-correction (bandshifting)0*4)*( and correct them as necessary.<(Ybon(42Z()#(E$#*4(8.K.5*$(EDc( To quantify the effects of k-correction on the identification of bars, we examined a local sample of 139 galaxies in all five Sloan bands (u, g,r,i,andz). We 1#2,-.2/45#()/(#4)*(Y".)/(3.K%-*Z selected nearby (<100 Mpc), face-on (b/a > 0:58), large (a 90% radius >2 kpc) and bright (MBY19:7, MB estimated from g r colors ,#-(*k%+5/()/(.+#3#5*+(Y".)/(3.K%-*(*1.2*Z and g-band magnitudes Blanton et al. 2003) spiral galaxies from the SDSS (York et al. 2000; Gunn et al. 1998) DataE%-"/c(YEF/5F(/5(*$9(àabZÀ Release 4 (Adelman-McCarthy et al. 2006). The data were mosaicked and calibrated using the methods described by West et al. (2007). -././01234.56.789.:.8:;5"<:=/:>9.>;9;8=?/ We used the same bar identification methods (ellipse fitting and visual classification; see 3)fortheSDSS dataasfortheCOSMOS data and measured the bar fraction in each band. The results are shown in Figure 7. The bar fractionx is unchanged from the z band to the g band at fbar 0:6. This is consistent with a number of previous studies (e.g., Meneńdez-Delmestre et al. 2007; Eskridge et al. 2002; (!45/4)/2#+(/+5/(3*5#()/".)#(*([%/(/2(0*4)*+( Whyte et al. 2002) that have shown that the overall bar fraction does not change appreciably(Q(.2,#-5*41.*().++#(4#(1#45/T5#()#( between the optical and near-infrared (Q5%*$2/45/(/+5*2#+(/T*2.4*4)#(+/(*(5/4)i41.*()*( bands. This figure also demonstrates that the shifting rest-wavelength of observation in our sample does not bias our measurements of the bar fraction, provided we restrict the maximum redshift of our sample appropriately. 2*.+(*B%.+(#(0#k#(A(2/4#+(,-#/2.4/45/(,#-(+/-( The maximum redshift chosen is important,,)* because Figure 7 shows thatL4."/-+#().+5*45/(A([%/(*(2/).)*([%/(#( the SDSS bar fraction does appear to decline markedly in /$.,5.1.)*)/(+/-(2*.#-(/2(0*4)*+(2*.+(*B%.+(+/(/+5/4)/( the u band. At this wavelength, in a majority of cases, the ellipse-fitting technique fails completely. This is not unexpected, and a component of this decline may find its origin in the relatively poor signal-to-noise ratio of the SDSS u-band data. However, we suspect that 1#2,#+5#(,-.2*-.*2/45/(,#-(/+5-/$*+("/$F*+(/( the bulk of this decline is real. Bars are primarily stellar structu/+5%)#()/(0*--*+(+/(/+5/4)/(,*-*(-/)+F.35+(res and some become significantly fainter and sometimes disappear *#(LJ altogether shortward of the Balmer break. A dramatic example of this is shown for the nearby strongly barred spiral NGC 4303 in Figure 1 of Sheth et al. (2003). This is further justification for our chosen limiting redshift in this paper, because by restricting our "/-2/$F*+e(4*+(0*4)*+(2*.+("/-2/$F*+(#( sample to z 0:835, the F814W filter does not probe9&6":"#&$'2&4%+,-",."##",4+,;9.>" N/3/-i41.*+g /2(*$5#(-/)+F.35g(/2(%2*()*)*(0*4)*(#0+/-"*)*=(/+,/-*2#+()/5/-2.4*-(%2*(3-*&'#( >/44.1%5=(N9(R9=(/5(*$9(àab=(VQEV=(\\o=(q`re(@/4A4)/BC8/$2/+5-/=(>9=(/5(*$9(/2(,-/,*-*&'#e( 1*)*("/B(2/4#-()/(/+,.-*.+(0*--*)*+(/2(2*.#-/+(-/)+F.35+ EF/5F=(>9=(/5(*$9(àab=(Q,:=(oq`=(\be(EF/5F=(>9=(/5(*$9(àar=(Q,:=(]so=(\\n\e(EF/5F=(>9=(/5(*$9(à\a=(VQEV=(\``=(\bqse((Q(.2,#-5*41.*().++#(4#(1#45/T5#()#( (Q5%*$2/45/(/+5*2#+(/T*2.4*4)#(+/(*(5/4)i41.*()*( L4."/-+#().+5*45/(A([%/(*(2/).)*([%/(#(!T,-/++#(2/%(*K-*)/1.2/45#(*#(RPV[(,/$#(3.4*41.*2/45#(/(*#(5.2/(Ed_(,/$*(1#$*0#-*&'# /$.,5.1.)*)/(+/-(2*.#-(/2(0*4)*+(2*.+(*B%.+(+/(/+5/4)/( /+5%)#()/(0*--*+(+/(/+5/4)/(,*-*(-/)+F.35+( *#(LJ 2*.+(*$5#+=(5-*&*2#+(0*4)*+(1*)*("/B(2*.+( tunnoa(v *B%.+(4#(-/3/-/41.*$()*(K*$7T.*9(E/(%+*2#+( (!+5/+(-/+%$5*)#+(.4).1*2([%/(/+5%)#+()/(0*--*+(/2(*$5#(-/)+F.35()/"/2($/"*-(/2( )*)#+(,-#3%4)#+(4*(0*4)*(O=(*(,*-5.-()/( 1#4+.)/-*&'#(#+(3*5#+()/([%/(*((64="(*%2/45*(4*+(0*4)*+(2*.+(*B%.+(4#(-/3/-i41.*$( Bwa9r(1#2/&*-?*2#+(*(5-*&*-(*+(0*4)*+( )*(K*$7T.*(/([%/(#(267-4'7+#)6()/+5*+(,/-2*4/1/(1#4+5*45/

PLJ=(,#)/4)#($/"*-(j(4'#C)/5/1&'#()*(! ! 0*--*(1#2#(2#+5-*(*(3.K%-* ( !+5%)#+( /2( *$5#( -/)+F.35( )/"/2( %5.$.B*-( /+5/+( -/+%$5*)#+( ,*-*( 1#--.K.-( *+( /$.,5.1.)*)/+( )*+( 0*--*+( )#+( /3/5.#+( )/( 0*4)+F.35.4K( ,*-*( [%/( %2*( .45-?4+/1*( (!T/2,$#()/(P_R(nosq(4*+(0*4)*+(b=]x2=( /"#$%&'#()*(3#-&*()*(0*--*(/2(K*$7T.*+(/+,.-*.+(,#++*(+/-(2/$F#-(*"*$.*)* O(/(PLJ=(#4)/(*(0*--*()/+*,*-/1/(4#(%$5-*( ".#$/5* t(uòaa(v (@A:!#EC (y(4/1/++7-.*(5*20A2(*(1#--/&'#(/2(/+5%)#+(+#0-/(*(3-*&'#()/(/+,.-*.+(1#2(0*--*+( -./1/0.234.56.789.:.8:;5":=/:>9.>" N/3/-i41.*+g /2(*$5#(-/)+F.35g(/2(%2*()*)*(0*4)*(#0+/-"*)*=(/+,/-*2#+()/5/-2.4*-(%2*(3-*&'#( >/44.1%5=(N9(R9=(/5(*$9(àab=(VQEV=(\\o=(q`re(@/4A4)/BC8/$2/+5-/=(>9=(/5(*$9(/2(,-/,*-*&'#e( 1*)*("/B(2/4#-()/(/+,.-*.+(0*--*)*+(/2(2*.#-/+(-/)+F.35+ EF/5F=(>9=(/5(*$9(àab=(Q,:=(oq`=(\be(EF/5F=(>9=(/5(*$9(àar=(Q,:=(]so=(\\n\e(EF/5F=(>9=(/5(*$9(à\a=(VQEV=(\``=(\bqse( !T,-/++#(2/%(*K-*)/1.2/45#(*#(RPV[(,/$#(3.4*41.*2/45#(/(*#(5.2/(Ed_(,/$*(1#$*0#-*&'# 1146 SHETH ET AL. Vol. 675

1146 SHETH ET AL. Vol. 675 Bar fracon declines with z, but almost exclusively Bar studies at high-redshift in the lower mass/later-type/bluer galaxies 1146 SHETH ET AL. Vol. 675 • Bar fracon declines at high redshi, but almost exclusively in the lower mass (10 < log M *(M ⊙) < 11), later-type, and bluer galaxies.

z=0.14-0.37 Fracon Bar z=0.37-0.60

z=0.60 -0.84

Sheth+08 ALMA Visitor Program, March 2014 Log (Mass) Karín Menéndez-Delmestre Fig. 3.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) Fig. 2.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) vs. total galaxy stellar mass in three redshift bins. As expected from Fig. 2, there is vs. the absolute magnitude (MV) in three redshift bins. There is a strong correla- astrongcorrelationbetweenthebarfractionandthemassforthehighestredshift tion between the bar fraction and the galaxy luminosity in the highest redshift bin. bin. In that bin, galaxies with log M > 10:9alreadyhavefbar 0:5, whereas gal- In that bin, the most luminous galaxies (MV < 23:5) have fbar 0:5, whereas axies with log M < 10:5havefbar < 0:2. The bar fraction for the entire population À the lowest luminosity (MV > 22:5) galaxies have a fbar 0:2. With redshift evolves with time with the largest change in the lowest mass bin. The same trend À we see a strong evolution in the low-luminosity sample as they evolve to fbar is seen in the bottom panel. The lack of high-mass galaxies in the lower redshift 0:6 in the lowest redshift bin. A similar trend is seen in the bottom panels for the bins is because, even with 2 deg2, the volume of space observed by COSMOS is strong bar fraction. The data points are at the midpoints of bins of MV 0:5, small. Luminosity and color selection criteria put a limit on the minimum detect- from 21.0 to 23.5 (a data point is skipped if no galaxies are found in a bin)¼ and able mass—our sample is complete for the points shown here. Each point is at the À À the errors bars are calculated as before. The first bin is from MV 23:5to left edge of bins of log M 0:15, starting from 10.0 (point skipped if no data is 24.75. The data points are slightly offset along the x-axis for each¼À redshift bin found in a bin). Errors bars¼ are calculated as before and last bin is from log M andÀ only the number of strong bars is labeled on the bottom panel for clarity. This 10:9Y11:5. The data points are slightly offset along the x-axis for each redshift bin¼ figure should be viewed together with Fig. 3. and only the number of strong bars is labeled on the bottom panel for clarity. The uncertainty in the mass measurement is afactorofthree.Thisfigureshouldbe viewed together with Fig. 2. Fig. 3.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) Elmegreen et al. (2004) also reported a constant bar fraction Fig. 2.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) vs. total galaxy stellar mass in three redshift bins. As expected from Fig. 2, there is to z 1:1 based on an analysis of 186 background galaxies Fig. 3.—Totalvs. the absolute bar fraction magnitude (top (M panelV) in)andstrongbarfraction( three redshift bins. There is abottom strong correla- panel) astrongcorrelationbetweenthebarfractionandthemassforthehighestredshift tion between the bar fraction and the galaxy luminosity in the highest redshift bin. bin. In that bin, galaxies with log M > 10:9alreadyhavefbar 0:5, whereas gal- Fig.2.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) vs. total galaxy stellar mass in three redshift bins. As expected from Fig. 2, there is larger than 10 pixels in diameter in the multicolor ACS image of In that bin, the most luminous galaxies (MV < 23:5) have fbar 0:5, whereas axies with log M < 10:5havefbar < 0:2. The bar fraction for the entire population and bar identification methods between theseÀ studies. These may vs. the absolute magnitude (MV) in three redshift bins. There is a strong correla- astrongcorrelationbetweenthebarfractionandthemassforthehighestredshiftthe lowest luminosity (MV > 22:5) galaxies have a fbar 0:2. With redshift evolves with time with the largest change in the lowest mass bin. The same trend the Tadpole galaxy. These data points are shown with the purple À tion between the bar fraction and the galaxy luminosity in the highest redshift bin. bin.be responsible In thatwe bin, see galaxies a strong for with evolutionsome log of inM the the> low-luminosity10 observed:9alreadyhave sample differences.fbar as they0:5, evolve whereas The to mainfbar gal- is seen in the bottom panel. The lack of high-mass galaxies in the lower redshift 2 trianglesIn that bin, in the Figure most luminous 6. The galaxies data show (MV a< declining23:5) have barfbar fraction0:5, whereas from axiespoint with to0 log note:6 inM the is< lowest that10:5have redshift in nearlyfbar bin.< A0 every: similar2. The trend study, bar fraction is seen the in for data the the bottom have entire panels population shown for the a bins is because, even with 2 deg , the volume of space observed by COSMOS is À the30% lowest to luminosity15% out (M toV >z 220::5)8 withgalaxies 3 haveuncertainty, a fbar 0:2. and With a redshiftrise in evolvesdecline withstrong in time the bar with bar fraction. the fraction, largest The data change pointsalthough arein the at the lowest the midpoints interpretations mass of bin. bins The of sameMV of trend0 the:5, small. Luminosity and color selection criteria put a limit on the minimum detect- À¼ from 21.0 to 23.5 (a data point is skipped if no galaxies are found in a bin)¼ and able mass—our sample is complete for the points shown here. Each point is at the thewe see bar a strong fraction evolution from inz the0 low-luminosity:8Y1:1, which sample is beyond as they evolve the redshift to fbar is seen in the bottomÀ panel.À The lack of high-mass galaxies in the lower redshift 0:6 in the lowest redshift14 bin. A similar trend is seen in the bottom panels for the binsdata is have because,the errors ranged even bars with are from 2 calculated deg a2, theconstant as volume before. of barThe space first fraction observedbin is from to byM aV COSMOS dramatic23:5to is left edge of bins of log M 0:15, starting from 10.0 (point skipped if no data is investigated here. Their¼ conclusion that the bar fraction is flat 24.75. The data points are slightly offset along the x-axis for each¼À redshift bin found in a bin). Errors bars¼ are calculated as before and last bin is from log M strong bar fraction. The data points are at the midpoints of bins of M 0 5, small.paucity Luminosity of bars and at colorz selection1. It is criteria only with put a limit the on COSMOS the minimum data detect- set V : andÀ only the number of strong bars is labeled on the bottom panel for clarity. This 10:9Y11:5. The data points are slightly offset along the x-axis for each redshift bin¼ onfrom average21.0 to followed23.5 (a data primarily point is skipped from if no the galaxies second are found rise in at a bin)z¼ and1; ablethat mass—our we are able sample to robustly is complete quantify for the points the shown decline here. in Each the bar point fraction is at the À À figure should be viewed together with Fig. 3. and only the number of strong bars is labeled on the bottom panel for clarity. The otherwisethe errors bars their are calculated fractions as agre before.ewithourstowithinstatistical The first bin is from MV 23:5to left edge of bins of log M 0:15, starting from 10.0 (point skipped if no data is uncertainty in the mass measurement is afactorofthree.Thisfigureshouldbe ¼À and show that the evolution¼ is a strong function of the galaxy lu- uncertainties.24.75. The data Our points results are slightly are also offset in along line the withx-axis a recent for each analysis redshift bin of found in a bin). Errors bars are calculated as before and last bin is from log M viewed together with Fig. 2. À minosity, mass,Elmegreen color, et al. and (2004) bulge also dominance. reported a constant bar fraction¼ theand only Hubble the number Ultra of Deep strong Field bars is where labeled onthe the bar bottom fraction, panel for shown clarity. with This 10:9Y11:5. The data points are slightly offset along the x-axis for each redshift bin figure should be viewed together with Fig. 3. and only theto numberz 1:1 of based strong on bars an is analysislabeled on of the 186 bottom background panel for clarity. galaxies The the blue triangle, is 10% (Elmegreen et al. 2005a) at z 1, uncertaintylarger in5.2. the than massFormation 10 measurement pixels in of diameter the is afactorofthree.Thisfigureshouldbe Hubble in the multicolor Sequence: ACS image of and bar identification methods between these studies. These may consistent with the previous HDF studies and the values obtained viewed togetherthe Tadpole with Fig. galaxy. 2. These data points are shown with the purple Elmegreen et al. (2004) also reported a constant bar fraction Assembling the Spiral Galaxies be responsible for some of the observed differences. The main in this paper. triangles in Figure 6. The data show a declining bar fraction from point to note is that in nearly every study, the data have shown a to Althoughz 1:1 based we have on anattempted analysis to of put 186 all the background data from galaxies various The declining30% to bar15% fraction out to z reported0:8 with in 3 thisuncertainty, paper shows and a thatrise in at ¼ decline in the bar fraction, although the interpretations of the larger than 10 pixels in diameter in the multicolor ACS image of alook-backtimeof7Gyr(the bar fraction from zz 00:8:Y835)1:1, which only about is beyond one-fifth the redshift of L data have ranged from a constant bar fraction to a dramatic studies into context, we emphasize that it is not straightforward and bar identification methods14 ¼ between these studies. These mayÃ tothe make Tadpole direct galaxy. comparisons These data because points of are different shown selection with the criteria purple bespiral responsible galaxiesinvestigated were for somehere. barred, ofTheir the which¼ conclusion observed is about that differences. one-third the bar fraction the The present is main flat paucity of bars at z 1. It is only with the COSMOS data set on average followed primarily from the second rise at z 1; triangles in Figure 6. The data show a declining bar fraction from pointday value. to note During is that the in nearly following every 3 Gyr study, (from the dataz 0 have:8to shownz 0:3) a that we are able to robustly quantify the decline in the bar fraction otherwise their fractions agreewithourstowithinstatistical and show that the evolution is a strong function of the galaxy lu- 30%14 Four to galaxies15% inout their to z Fig. 100:8 at withz 1 38areincorrectbecauseofapho- uncertainty, and a rise in declinethe bar fraction in the bar increased fraction, to roughly although its the present interpretations value. Only of small the ¼ : uncertainties. Our results are also in line with a recent analysis of minosity, mass, color, and bulge dominance. tometricthe bar redshift fraction error—the from z corrected0:8Y1 data:1, which point is is shown beyond here. the redshift datachanges have occurred ranged in from the last a constant 4 Gyr (z bar< 0 fraction:3). to a dramatic 14 ¼ the Hubble Ultra Deep Field where the bar fraction, shown with investigated here. Their conclusion that the bar fraction is flat paucitythe of barsblue triangle, at z 1. is It10% is only (Elmegreen with the et COSMOS al. 2005a) at dataz set1, 5.2. Formation of the Hubble Sequence: on average followed primarily from the second rise at z 1; consistent with the previous HDF studies and the values obtained that we are able to robustly quantify the decline in the bar fraction Assembling the Spiral Galaxies otherwise their fractions agreewithourstowithinstatistical and showin that this paper. the evolution is a strong function of the galaxy lu- uncertainties. Our results are also in line with a recent analysis of minosity, mass,Although color, we have and attemptedbulge dominance. to put all the data from various The declining bar fraction reported in this paper shows that at studies into context, we emphasize that it is not straightforward alook-backtimeof7Gyr(z 0:835) only about one-fifth of LÃ the Hubble Ultra Deep Field where the bar fraction, shown with ¼ the blue triangle, is 10% (Elmegreen et al. 2005a) at z 1, to make direct comparisons because of different selection criteria spiral galaxies were barred, which is about one-third the present 5.2. Formation of the Hubble Sequence: day value. During the following 3 Gyr (from z 0:8toz 0:3) consistent with the previous HDF studies and the values obtained 14 FourAssemblin galaxies in theirg the Fig. 10 Spiral at z 1 Galaxies:8areincorrectbecauseofapho- the bar fraction increased to roughly its present value. Only small in this paper. tometric redshift error—the corrected data point is shown here. changes occurred in the last 4 Gyr (z < 0:3). Although we have attempted to put all the data from various The declining bar fraction reported in this paper shows that at studies into context, we emphasize that it is not straightforward alook-backtimeof7Gyr(z 0:835) only about one-fifth of LÃ to make direct comparisons because of different selection criteria spiral galaxies were barred, which¼ is about one-third the present day value. During the following 3 Gyr (from z 0:8toz 0:3) 14 Four galaxies in their Fig. 10 at z 1:8areincorrectbecauseofapho- the bar fraction increased to roughly its present value. Only small tometric redshift error—the corrected data point is shown here. changes occurred in the last 4 Gyr (z < 0:3). 1146 SHETH ET AL. Vol. 675

z=0.14-0.37 Fracon Bar z=0.37-0.60

z=0.60 -0.84 High-mass end

z=0.14-0.37 Fracon à Low stellar mass Bar z=systems formed 0.37-0.60 their bars most recently z=0.60 -0.84 High-mass end (downsizing!)

1146 SHETH ET AL. Vol. 675 Bar fracon declines with z, but almost exclusively Bar studies at high-redshift in the lower mass/later-type/bluer galaxies • Bar fracon declines at high redshi, but almost exclusively in the lower mass (10 < log M *(M ⊙) < 11), later-type, and bluer galaxies.

Fracon Bar

[based on HST resrame opcal]

be compromised: the authors mention that their images are not deep the galaxy near the bar end, since it is about this region where the bar enough and the resulting parameters are uncertain. Since their im- isophotes reach their peak in ellipticity, and the bulge component ages are in the near-IR and ours in the optical, and given that galaxies is usually faint there. As the disc of NGC 5850 is very faint, this usually become bluer outwards (but see Gadotti & dos Anjos 2001), dilution is not efficient in this galaxy. the scalelengths obtained here could indeed be somewhat larger These results have implications on previous findings in the lit- than theirs. This systematic difference seems to be present in Fig. 5 erature. For instance, Marinova & Jogee (2007) measured the bar but complicates these comparisons. This difference in wavelength ellipticity via ellipse fits in a sample of 180 barred galaxies. They could also explain the different results for NGC 3227, 4314 and found that only a minority of the bars in their sample have elliptici- 4593, which have significant amounts of dust and star formation ties below 0.4, and that most bars have ellipticities between 0.5 and which certainly haveastronger effect in the optical than in the near- 0.8, with a mean value of about 0.5. As I have just shown, ellipse fits IR. In particular, NGC 4314 has very bright star-forming nuclear systematically underestimate the true bar ellipticity by 20 per cent, spiral arms that show up clearly in the residual image. The light on average. This means that the paucity of weak bars, i.e. those with from these spirals is partially attributed to the bulge component, ellipticities below 0.4, is even more pronounced. Manyof these and, since these spirals should not be so conspicuous in the near-IR, bars in their sample might have higher ellipticities, which, however, this can explain why I obtain a much more massive bulge than Lau- cannot be reliably measured with ellipse fits due to the effects just rikainen et al. On the other hand, it is not clear why our results are discussed. Furthermore, the fraction of bars with high ellipticities discrepant for the bulge of NGC 5701, although the difference in the is, in fact, even higher, as is the true mean value for the ellipticity Sérsic index is within typical 1σ errors. Furthermore, it is unclear of bars. A simple calculation gives a true mean value of around 0.6, if the AGN light should have been taken into account also in their considering an underestimation of 20 per cent. near-IR images. Taken altogether, this general agreement, and the It should be noted that the bar strength does not depend only fact that with the results presented here it is possible to reproduce on the bar ellipticity, but also on its shape (more rectangular, boxy some known results (Figs 2, 3 and 4) are very encouraging. bars, i.e. those with higher c, are stronger) and its mass (see also discussion in Marinova & Jogee 2007, and references therein). The strength of a bar is thus directly connected to the amplitude of the 3.4 The ellipticity of bars non-axisymmetric potential it introduces in the overall potential well To measure the ellipticity of a bar, one usually fits ellipses to the of its host galaxy. With this definition, the strength of a bar does not galaxy image and assumes that the bar ellipticity is that of the most depend on any other of the properties of its host galaxy. On the eccentric fitted ellipse (e.g. Marinova & Jogee 2007). This is a very other hand, the impact of a bar on the evolution of a galaxy depends important parameter because it is strongly related with the strength on other galaxy properties. A strong bar will significantly modify of the bar, and can provide constraints for bar models, like those of the dynamics of gas and stars in a galaxy with a relatively weak e.g. Athanassoula & Misiriotis (2002) and secular evolution scenar- axisymmetric potential, i.e. a galaxy where the bar mass is high ios (e.g. Gadotti & dos Anjos 2001). In Fig. 6, the ellipticity of bars compared to the bulge and disc masses. The same bar would produce as estimated from the image decompositions are plotted against the less significant effects in a galaxy with massive bulge and disc. ellipticity peak in the ellipse fits of GdS06. The latter is used as a Furthermore, since the axisymmetric component of the potential is starting point for the decompositions but the bar ellipticity is a free centrally concentrated, mainly due to the bulge, the changes due to parameter in the fits. It is clear that ellipse fits underestimate the the bar are likely to haveadependence on radius and to be more true ellipticity of the bar. This effect is on average about 20 per cent, significant closer to the bar ends. but it can be as large as a factor of 3. For NGC 5850, however, the nd match between2 the result:two parameters barsis excellent. lookExamining thinnerthe cases in bluer3.5 Disc bandsconsumption in NGC 4608 and 5701 where this effect is strongest, as in NGC 4267 and 4303, reveals its origin: the ellipticity of the isophotes in the bar region is diluted It is not uncommon to see in residual images such as those in Fig. 1 by the contribution from the round, axisymmetric component of the regions with evident negative residuals, where the fitted model is • εmax is higher in the opcal galaxy. The strength of this effect is thus governed by thebands, compared to the mid-IR difference brighter than the galaxy. In some cases, this is clearly a result of between the contributions of the bar and the disc to the total light in dust extinction, butin other cases their presence might mean that • This result extends to the UV the models used are not fully adequate. Inspecting the results in Fig. 1, it is possible to identify two particular cases where such neg- 0.8 ative residuals are not only conspicuous, but also clearly delineate • a distinct region in the residual image. These are NGC 4608 and N4303 Driven by bulge sizes: N4267 5701. In their residual images, one is able to spot a region in the 0.6 N5850 • Bulge looks bigger in redder disc where the models are definitely brighter than the galaxies. It can

bar bands à smaller in the blue be described as two crescents, one at each side of the bar, but out of Budda ε ε 0.4 it (pointed out by the red arrows in Fig. 1). In NGC 4608, these cres- - Limits the size of the bar cents extend to a radius similar to the bar semimajor axis length, i.e. Δεband-shiing ~15-20% thinner : 0.07 (up to 0.14) semi-minor axis up to the inner ring surrounding the bar. In NGC 5701, this region 0.2 : 0.07 (up to 0.15) • In good agreement with is more extended, and the crescents occupy the whole area between the bar and the outer ring. In Gadotti & de Souza (2003), this less lu- 0.2 0.4 0.6 0.8 BUDDA results (Gado+08) minous area in the disc component of these galaxies was identified, ε Gado+08 max and it was pointed out that the N-body models of bar formation and Figure 6. Ellipticity of bars estimated from image decomposition plotted evolution presented in Athanassoula & Misiriotis (2002) produce Figura 32: Histograma e gráfico de dispersãoagainst representandothe ellipticityThe peakbluerin osellipse valores the fits from medidosresrameGdS06. Some para band, the interesting cases thinnera very the bar!similar feature, particularly their models which lead to the are DAS Seminar (U. de Chile), March 19, 2014indicated. The solid line indicates a perfect correspondence. It is clear Karínformation Menéndez-of veryDelmestrestrong bars (see their fig. 3). Athanassoula (2002, aelipticidadedabarrautilizandoométododaelipticidademáxima.that ellipse fits systematically underestimate the true ellipticity of the bar. 2003) presents theoretical work which shows that bars get longer

⃝C 2008 The Author. Journal compilation ⃝C 2008 RAS, MNRAS 384, 420–439

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

61 Bar studies at high-redshift

• Bar fracon declines at high redshi – Based in either visual or ellip/PA classiﬁcaon

Fracon Fracon Bar Bar

Redshi Redshi Sheth+08 ALMA Visitor Program, March 2014 Karín Menéndez-Delmestre 1146 SHETH ET AL. Vol. 675

Bar studies at high-redshift 1146 SHETH ET AL. Vol. 675 • Bar fracon declines at high redshi, but almost exclusively in the lower mass (10 < log M *(M ⊙) < 11), 1146 later-type, and bluer galaxies. SHETH ET AL. Vol. 675

Fig. 3.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) Fig. 2.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) vs. total galaxy stellar massSheth+08 in three redshift bins. As expected from Fig. 2, there is vs. the absolute magnitude (MV) in three redshiftALMA Visitor Program, March 2014 bins. There is a strong correla- astrongcorrelationbetweenthebarfractionandthemassforthehighestredshift Karín Menéndez-Delmestre tion between the bar fraction and the galaxy luminosity in the highest redshift bin. bin. In that bin, galaxies with log M > 10:9alreadyhavefbar 0:5, whereas gal- In that bin, the most luminous galaxies (MV < 23:5) have fbar 0:5, whereas axies with log M < 10:5havefbar < 0:2. The bar fraction for the entire population À the lowest luminosity (MV > 22:5) galaxies have a fbar 0:2. With redshift evolves with time with the largest change in the lowest mass bin. The same trend À we see a strong evolution in the low-luminosity sample as they evolve to fbar is seen in the bottom panel. The lack of high-mass galaxies in the lower redshift 0:6 in the lowest redshift bin. A similar trend is seen in the bottom panels for the bins is because, even with 2 deg2, the volume of space observed by COSMOS is strong bar fraction. The data points are at the midpoints of bins of MV 0:5, small. Luminosity and color selection criteria put a limit on the minimum detect- from 21.0 to 23.5 (a data point is skipped if no galaxies are found in a bin)¼ and able mass—our sample is complete for the points shown here. Each point is at the À À the errors bars are calculated as before. The first bin is from MV 23:5to left edge of bins of log M 0:15, starting from 10.0 (point skipped if no data is 24.75. The data points are slightly offset along the x-axis for each¼À redshift bin found in a bin). Errors bars¼ are calculated as before and last bin is from log M andÀ only the number of strong bars is labeled on the bottom panel for clarity. This 10:9Y11:5. The data points are slightly offset along the x-axis for each redshift bin¼ figure should be viewed together with Fig. 3. and only the number of strong bars is labeled on the bottom panel for clarity. The uncertainty in the mass measurement is afactorofthree.Thisfigureshouldbe viewed together with Fig. 2. Elmegreen et al. (2004) also reported a constant bar fraction to z 1:1 based on an analysis of 186 background galaxies Fig. 3.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) largerFig. 2.—Total than 10 barpixels fraction in diameter (top panel)andstrongbarfraction( in the multicolor ACSbottom image panel of) vs.and total bar galaxy identification stellar mass inmethods three redshift between bins. As these expected studies. from Fig. These 2, there may is vs.the the Tadpole absolute galaxy. magnitude These (MV) in data three points redshift are bins. shown There is with a strong the correla-purple astrongcorrelationbetweenthebarfractionandthemassforthehighestredshiftbe responsible for some of the observed differences. The main tion between the bar fraction and the galaxy luminosity in the highest redshift bin. bin. In that bin, galaxies with log M > 10:9alreadyhavefbar 0:5, whereas gal- triangles in Figure 6. The data show a declining bar fraction from point to note is that in nearly every study, the data have shown a In that bin, the most luminous galaxies (MV < 23:5) have fbar 0:5, whereas axies with log M < 10:5havefbar < 0:2. The bar fraction for the entire population 30% to 15% out to z 0:8 with 3À uncertainty, and a rise in the lowest luminosity (MV > 22:5) galaxies have a fbar 0:2. With redshift evolvesdecline with in time the with bar the fraction, largest change although in the lowest the interpretations mass bin. The same of trend the À¼ wethe see bar a strong fraction evolution from inz the low-luminosity0:8Y1:1, which sample is beyond as they evolve the redshift to fbar isdata seen have in the bottom ranged panel. from The a lack constant of high-mass bar galaxies fraction in the to lower a dramatic redshift 14 ¼ 2 0investigated:6 in the lowest here. redshift bin.Their A similar conclusion trend is seen that in the the bar bottom fraction panels foris flat the binspaucity is because, of bars even at withz 2 deg1. It, the is volume only with of space the observed COSMOS by COSMOS data set is strongon average bar fraction. followed The data primarily points are at from the midpoints the second of bins rise of M atV z 0:1;5, small. Luminosity and color selection criteria put a limit on the minimum detect- from 21.0 to 23.5 (a data point is skipped if no galaxies are found in a bin)¼ and ablethat mass—our we are able sample to robustly is complete quantify for the points the shown decline here. in Each the bar point fraction is at the otherwiseÀ theirÀ fractions agreewithourstowithinstatistical the errors bars are calculated as before. The first bin is from MV 23:5to leftand edge show of bins that of the log evolutionM 0:15, isstarting a strong from function10.0 (point of skipped the galaxy if no data lu- is uncertainties. Our results are also in line with a recent analysis¼À of ¼ 24.75. The data points are slightly offset along the x-axis for each redshift bin foundminosity, in a bin). mass, Errors color, bars are and calculated bulge as dominance. before and last bin is from log M Fig. 3.—Total bar fraction (top panel)andstrongbarfraction(bottom panel) andÀthe only Hubble the number Ultra of Deep strong Field bars is wherelabeled on the the bar bottom fraction, panel for shown clarity. with This 10:9Y11:5. The data points are slightly offset along the x-axis for each redshift bin¼ figurethe blue should triangle, be viewed is together10% with (Elmegreen Fig. 3. et al. 2005a)Fig. 2.—Total at z 1, barand fraction only the (numbertop panel of strong)andstrongbarfraction( bars is labeled on the bottom panelbottom for clarity. panel The ) vs. total galaxy stellar mass in three redshift bins. As expected from Fig. 2, there is 5.2. Formation of the Hubble Sequence: consistent with the previous HDF studies and thevs. values the absolute obtained magnitudeuncertainty (M in) the in mass three measurement redshift is bins.afactorofthree.Thisfigureshouldbe There is a strong correla- astrongcorrelationbetweenthebarfractionandthemassforthehighestredshift viewed togetherV withAssemblin Fig. 2. g the Spiral Galaxies inElmegreen this paper. et al. (2004) also reported a constanttion between bar fraction the bar fraction and the galaxy luminosity in the highest redshift bin. bin. In that bin, galaxies with log M > 10:9alreadyhavefbar 0:5, whereas gal- to Althoughz 1:1 based we have on an attempted analysis to of put 186 all backgroundtheIn data that from bin, galaxies various the most luminousThe declining galaxies bar ( fractionM < reported23:5) in have thisf paper shows0:5, whereas that at axies with log M < 10:5havef < 0:2. The bar fraction for the entire population alook-backtimeof7Gyr(V z 0:835) only aboutbar one-fifth of L bar largerstudies than into 10 context, pixels in we diameter emphasize in the that multicolor it is not straightforward ACS image of and bar identification methodsÀ between these studies. These mayÃ the lowest luminosityspiral (MV galaxies> 22 were:5) galaxies barred, which¼ have is a aboutfbar one-third0:2. With the present redshift evolves with time with the largest change in the lowest mass bin. The same trend theto make Tadpole direct galaxy. comparisons These data because points of are different shown selection with the criteria purple be responsibleÀ for some of the observed differences. The main triangles in Figure 6. The data show a decliningwe bar see fraction a strong from evolutionday value. in the During low-luminosity the following sample 3 Gyr (from as theyz evolve0:8toz to 0fbar:3) is seen in the bottom panel. The lack of high-mass galaxies in the lower redshift point to note is that in nearly every study, the data have shown a 2 14 0 6 in the lowest redshiftthe bar bin. fraction A similar increased trend to is roughly seen in its the present bottom value. panels Only small for the bins is because, even with 2 deg , the volume of space observed by COSMOS is 30%Four to galaxies15% out in their to z Fig.0 10:8 at withz 1 3:8areincorrectbecauseofapho- uncertainty,: and a rise in decline in the bar fraction, although the interpretations of the tometric redshift error—the corrected¼ data point is shown here. changes occurred in the last 4 Gyr (z < 0:3). the bar fraction from z 0:8Y1:1, which is beyondstrong the bar redshift fraction. Thedata data have points ranged are from at the a constant midpoints bar offraction bins toof aM dramaticV 0:5, small. Luminosity and color selection criteria put a limit on the minimum detect- 14 ¼ ¼ investigated here. Their conclusion that thefrom bar fraction21.0 is to flat 23.5paucity (a data pointof bars is at skippedz 1. It if is no only galaxies with the are COSMOS found in a data bin) set and able mass—our sample is complete for the points shown here. Each point is at the on average followed primarily from the second riseÀ at z 1;À the errors bars are calculatedthat we are ableas before. to robustly The quantify first bin the declineis from inM theV bar fraction23:5to left edge of bins of log M 0:15, starting from 10.0 (point skipped if no data is otherwise their fractions agreewithourstowithinstatistical24.75. The data pointsand show are slightly that the offsetevolution along is a strong the x-axis function for ofeach the¼À redshift galaxy lu- bin found in a bin). Errors bars¼ are calculated as before and last bin is from log M uncertainties. Our results are also in line with aÀ recent analysis of minosity, mass, color, and bulge dominance. ¼ the Hubble Ultra Deep Field where the bar fraction,and only shown the with number of strong bars is labeled on the bottom panel for clarity. This 10:9Y11:5. The data points are slightly offset along the x-axis for each redshift bin the blue triangle, is 10% (Elmegreen et al.figure 2005a) should at z be1, viewed together with Fig. 3. and only the number of strong bars is labeled on the bottom panel for clarity. The 5.2. Formation of the Hubble Sequence: consistent with the previous HDF studies and the values obtained Assembling the Spiral Galaxies uncertainty in the mass measurement is afactorofthree.Thisfigureshouldbe in this paper. viewed together with Fig. 2. Although we have attempted to put all the dataElmegreen from various et al.The (2004) declining also bar fraction reported reported a constant in this paper bar shows fraction that at studies into context, we emphasize that it is not straightforward alook-backtimeof7Gyr(z 0:835) only about one-fifth of LÃ to make direct comparisons because of differentto selectionz 1 criteria:1 basedspiral on galaxies an analysis were barred, of which¼ 186 is background about one-third the galaxies present larger than 10 pixelsday value. in diameter During the infollowing the multicolor 3 Gyr (from z ACS0:8to imagez 0:3) of and bar identification methods between these studies. These may 14 Four galaxies in their Fig. 10 at z 1:8areincorrectbecauseofapho-the Tadpole galaxy.the bar These fraction data increased points to roughly are shown its present with value. the Only purple small tometric redshift error—the corrected data point is shown here. changes occurred in the last 4 Gyr (z < 0:3). be responsible for some of the observed differences. The main triangles in Figure 6. The data show a declining bar fraction from point to note is that in nearly every study, the data have shown a 30% to 15% out to z 0:8 with 3 uncertainty, and a rise in ¼ decline in the bar fraction, although the interpretations of the the bar fraction from z 0:8Y1:1, which is beyond the redshift data have ranged from a constant bar fraction to a dramatic 14 ¼ investigated here. Their conclusion that the bar fraction is flat paucity of bars at z 1. It is only with the COSMOS data set on average followed primarily from the second rise at z 1; that we are able to robustly quantify the decline in the bar fraction otherwise their fractions agreewithourstowithinstatistical and show that the evolution is a strong function of the galaxy lu- uncertainties. Our results are also in line with a recent analysis of minosity, mass, color, and bulge dominance. the Hubble Ultra Deep Field where the bar fraction, shown with the blue triangle, is 10% (Elmegreen et al. 2005a) at z 1, 5.2. Formation of the Hubble Sequence: consistent with the previous HDF studies and the values obtained Assembling the Spiral Galaxies in this paper. Although we have attempted to put all the data from various The declining bar fraction reported in this paper shows that at studies into context, we emphasize that it is not straightforward alook-backtimeof7Gyr(z 0:835) only about one-fifth of LÃ to make direct comparisons because of different selection criteria spiral galaxies were barred, which¼ is about one-third the present day value. During the following 3 Gyr (from z 0:8toz 0:3) 14 Four galaxies in their Fig. 10 at z 1:8areincorrectbecauseofapho- the bar fraction increased to roughly its present value. Only small tometric redshift error—the corrected data point is shown here. changes occurred in the last 4 Gyr (z < 0:3). 1144 SHETH ET AL. Vol. 675

Our lowest mass data point in the 0:6 < z < 0:84 bin (the highest redshift bin) in Figure 3 is for galaxies with masses between 10 Bar studies at Sheth+08 (3Y4) ; 10 M . It is therefore free from the possible mass selection bias. The data points at lower masses and lower redshifts are high-redshift also computed from a complete sample of masses for a given bin. Thus we conclude that the observed strong correlation between the bar fraction and mass in the highest redshift bin is a robust result. • Both the total and The most important result in these figures is that in the highest redshift bins in this study, a majority of the most massive the strong bar and luminous systems are barred. There is little evolution in the fracon declines at bar fraction with redshift in these systems. Since bars form in massive, dynamically cold and rotationally supported galaxies, high redshi the high bar fraction indicates that the most massive systems are already ‘‘mature’’ enough to host bars. This agrees with the analysis of the evolution of the size function of disk galaxies of several studies (Sargent et al. 2007; Ravindranath et al. 2004; Barden et al. 2005; Sheth et al. 2008), which find that large disks are already in place by z 1andlittleornoevolutionindisk sizes from z 1tothepresentepoch.Converselythelowbar¼ fraction in the lower luminosity, lower mass systems indicates that these systems are either dynamically hot, not rotationally supported and/or have not accreted sufficient mass to host bars. Merging activity, which is more common at higher redshifts, is also likely to affect the less massive systems more severely and may be responsible for heating them up more than high-mass systems. Bar formation may be delayed in these hot disks if they ALMA Visitor Program, March 2014 Karín Menéndez-Delmestre are embedded in a massive dark matter halo. Although the exact Fig. 1.—Evolution of the bar fraction as a function of redshift in equal bins nature of these disks is not yet well known, there is an indication from z 0:0 to z 0:84, out to a look-back time of 7 Gyr. The bar fraction drops from 65%¼ in the local¼ universe to about 20% at z 0:84. The fraction of strong that later type systems may be dynamically hotter (Kassin et al. bars (SBs) drops from about 30% to under 10%. The top row shows the results 2007). We consider these points further in following sections. from the visual classification and the bottom row shows the results based on classification using the ellipticity and position angle profiles. The left column shows 4.3. Bar Fraction as a Function of Galaxy Color the bar fraction for all galaxies classified as bars, whereas the right column shows and BulgeLuminosity the same only for the strong bars. The error bars are calculated as f 1 f /N 1/2, where f is the fraction of galaxies, and N is the number of galaxies½ðÞÀ in a given Figure 4 shows how fbar varies with galaxy SED type (Tphot ) category. The numbers above each data point show the total number of bars (or and redshift. At low redshift, fbar is independent of Tphot,andat strong bars)/total number of galaxies in the bin. high redshift, fbar decreases from early (Tphot < 3) to late types (Tphot > 3). Similarly, fbar decreases with redshift more strongly are consistent with a roughly constant bar fraction ( fbar 0:6, for the late types than the early types. This latter trend is consis- ¼ fSB 0:3). These results are summarized in Table 1. tent with the previous result that the bar fraction changes with ¼ redshift primarily for the low-mass galaxies, which tend to have 4.2. Bar Fraction as a Function of Galaxy Mass & Luminosity late SED types. Figures 2 and 3 show fbar versus the absolute luminosity and Finally we consider how the bar fraction varies as a function mass of the disk, respectively, inthethreeredshiftbinsfrom of thebulgelightingalaxies.Figure5shows fbar versus the frac- z 0:14 to z 0:84. We find that in the highest redshift bin, tion of bulge luminosity in a galaxy for different redshift bins. ¼ ¼ galaxies with masses log M(M ) > 10:9andluminositiesMV < The bulge magnitude is calculated from fitting each galaxy with

23:5havefbar 0:5, which is about the local value. In contrast, aSe´rsic+exponential profile using GALFIT (Peng et al. 2002). À the low-mass (log M < 10:5) and low-luminosity (MV > 22:5) The x-axis in this figure is the difference between the bulge mag- À galaxies have fbar < 0:2athighredshift.Thesametrendisseen nitude measured from the GALFIT fitting and the total (disk+ for strong bars, fSB. At low redshifts, the bar fraction is roughly bulge) apparent magnitude. We note that the relative calibration equal for all luminosities. across redshift bins should be treated with caution because we This trend is not due to incompleteness in the sample. We are not correcting for k-correction effects that are known to affect establish the completeness of our sample by measuring the mass two-dimensional decomposition of galaxies. Within a given red- limit based on our selection criteria. Since we choose galaxies shift bin, however, the bulge contribution measurement should based on a luminosity cutoff and galaxy colors, the mass com- be robust except for one important caveat. The fitting algorithm pleteness is most likely to be an issue for the reddest systems at is not designed to decompose a bar separately. As a result the bar the highest redshift. For our luminosity cutoff and Tphot criteria, light is likely to be split between the exponential and Se´rsic our sample is complete for galaxies with masses greater than components. If the light profile of a bar is exponential, as it is 10 (3Y4) ; 10 M at z 0:9forthereddest(Tphot 2, rest-frame in later Hubble-type galaxies locally, the majority of that light ¼ ¼ Ámg r > 0:56) galaxies. Obviously, for the bluest systems is likely to be part of the exponential component. On the other À 10 (e.g., Tphot 6), our sample is complete to (0:9Y1) ; 10 M . hand, if the bar is relatively short and not highly elliptical, its These values¼ are calculated from the Maraston (2005) and Bell light is likely to be added to the Se´rsic component. The detailed et al. (2005) models, respectively. Note that at z 0:6, the mass decomposition of the bulge+bar+disk will require a more so- limit for completeness in the sample is lowered by¼ another 25%. phisticated approach, which is beyond the scope of this paper. Bars, bars, bars • Bars are very important cosmological signposts for inferring disk assembly – Disk “maturity”: a galaxy disk will naturally form a bar in a couple of Gyrs unless it is dynamically hot or is dominated by dark maer. • Local bar fracon is ~2/3 (opcal: de Vaucouleurs; near-IR: KMD+07) • Hot disks do not host bars (Sheth+12) –8– Tully Fisher – However, not every disk galaxy that is massive and Unbarred cold has a stellar bar à mass Barred Clump Galaxies and dynamic coldness of a Chain Galaxies disk are necessary but not sufficient condions for bar formaon! – Interacon history w/ dark maer halo is a key parameter in determining bar formaon Sheth+12

Fig. 3.— Stellar mass and rotational velocities for the different galaxy types classifications are plotted. The dashed lines show the width of the stellar TF-relationship between z∼0toz∼1as derived by Bell & de Jong (2001) and Conselice et al. (2005) respectively (and as shown in Figure 1ofKassinetal.(2007)).Theverticalsolidlineisthesameas that in Figure 2, showing the limits of our measurement. The symbols for the different galaxies are as follows: dark filled circles - unbarred disks; blue triangles - long bars, light blue rectangles - short bars, filled red circles - round compact, filled orange circles - non-round compact, green triangles - clump clusters and filled stars are chain galaxies. The black circles encircling some of the data points indicate galaxies for which the measured rotational velocity or velocity dispersion areuncertainduetothelimitationsofthe observations.

data also suggest that bars may be growing from short to long asthedisksevolvetocolderand more massive systems, indicating that bar-driven heating ofthediskislesssigniﬁcantthanthe competing cooling processes.

Previous studies have shown a strong correlation between thebarfraction,stellarmassofthe 11 galaxy and redshift such that massive galaxies (> 10 M⊙)hadahigh(>50%) bar fraction at 10 z∼0.85, whereas lower mass galaxies (10 M⊙)hadabarfraction< 20% (Sheth et al. 2008). The evolution of the bar fraction was diﬀerential over the last 7 Gyr with the fastest growth of the bar fraction occurring in the low mass, blue, late type spirals of masses between 1010 and 1011 M⊙(Sheth et al. 2008; Cameron et al. 2010). The present DEEP2/AEGIS sample is too small to Low-mass bars… why so few?

• Stellar mass of the disk seems to be a key quanty with which the bar fracon evolves over me! – bar fracon declines at high redshi, but almost exclusively in the

lower mass (10 < log M *(M ⊙) < 11), later-type, and bluer galaxies. à Low stellar mass systems formed their bars most recently (downsizing) • Today log M* ~ 9.2 seems to be the turnover point for bar fracon – Bar fracon drops for low-mass galaxies

Sheth et al. in prep 8. Description of the proposed programme and attachments

REFERENCES Athanassoula, E., 1983, IAU Symp., 100, 243 Athanassoula, E., 2003, MNRAS, 341, 1179 Athanassoula, E., 2005, MNRAS, 358, 1477 Athanassoula, E., Lambert, J.C., Dehnen, W., 2005, MNRAS, 363, 496 Bosma, A., 1983, IAU Symp., 100, 253 Buta, R. et al., 2010, ApJS, 190, 147 Bournaud, F., Combes, F., 2002, A&A, 392, 83 Elmegreen, B.G. et al., 2007, ApJ, 670, 97 Gadotti, D.A., de Souza, R.E., 2005, ApJ, 629, 797 Gadotti, D.A., de Souza, R.E., 2006, ApJS, 163, 270 Gadotti, D.A., 2008, in Chaos in Astronomy, G. Contopoulos, P.A. Patsis (eds.), in press Kormendy, J., 1979, ApJ, 227, 714 Kormendy, J., Kennicutt, R.C., 2004, ARA&A, 42, 603 Laurikainen, E. et al., 2010, MNRAS, 405, 1089 Martin, P., Roy, J-R., 1994, 424, 599 Menendez-Delmestre, K. et al., 2007, ApJ, 657, 790 Shen, J., Sellwood, J.A., 2004, ApJ, 604, 614 Metallicity Gradients Sheth, K. et al., 2008, ApJ,• A bar can affect significantly its host: transporng gas inwards it can lead 675, 1141 Vila-Costas, M.B., Edmunds, M.G., 1992, MNRAS, 259, 121 (e.g., Sheth+05) Zaritsky, D., Kennicutt, R.C.,to a central accumulaon of molecular gas Huchra, J.P., 1994, ApJ, 420, 87 , triggering nuclear starbursts, leading to the formaon of pseudobulges (e.g., Kormendy & Kennicu 04) , perhaps even feeding an AGN • Expectaon that barred and unbarred galaxies should have different metallicity signatures, where barred galaxies show flat nebular emission metallicity gradients in the disk region - slope of the O/H radial gradient as a funcon of bar strength à stronger bars have flaer gradients - Furthermore, it has been suggested that bars can leave a lens behind aer their dissoluon à if bars indeed dissolve, one expects to find unbarred lens galaxies showing flat gradients (Gado et al.) Marn & Roy (1994)

Fig. 1: Left: Slope of the O/H abundance radial gradient from Vila-Costas & Edmunds (1992 - upper panels) and Zaritsky et al. (1994 - lower panels) as a function of Hubble type. Barred galaxies are shown as open triangles. Clearly, all barred galaxies have ﬂat gradients. Right: slope of the O/H abundance radial gradient from Martin & Roy (1994) as a function of bar strength parameterized as bar ellipticity. The stronger the bar the ﬂatter the gradient.

Fig. 2: The lens in NGC 1291 is clearly visible as a thick eccentric structure surrounding the bar and right next to it (left). It is also easily recognized as a ﬂat feature in the galaxy radial surface brightness proﬁle (right) (Adapted from A. Bosma et al., in prep., using an IRAC 3.6µm image).

-3- Metallicity Gradients • A bar can affect significantly its host: transporng gas inwards it can lead to a central accumulaon of molecular gas (e.g., Sheth+05), triggering nuclear starbursts, leading to the formaon of pseudobulges (e.g., Kormendy & Kennicu 04) , perhaps even feeding an AGN • Expectaon that barred and unbarred galaxies should have different metallicity signatures, where barred galaxies show flat nebular emission metallicity gradients in the disk region • However, current CALIFA studies are coming out “empty handed” on this respect (see also Sánchez-Blázquez+11) ; Calar Alto Legacy Integral Field Area Survey (Sánchez+12) of ~600 local galaxies • Cacho+13, Ruiz-Lara+13: find no difference in the gaseous or stellar abundances (and distribuon) of barred and unbarred galaxies – Based on STARLIGHT, applied in a sistemac way to all CALIFA galaxies à evoluonary curves and radial profiles of physical properes • The jury is sll out! – Difficult to break the age-metallicity degeneracy Bars in the Local Universe • Locally, 2/3 of all disk galaxies have a bar. • A bar can induce large-scale streaming gas moons that can dramacally change the host galaxy. – Wash out metallicity gradient across galaxy (Marn & Roy 2004; but Sánchez-Blázquez+11) – Increase central gas concentraon à Trigger bursts of star formaon à Feed SMBH? – The bar fracon stays prey constant across wavelengths from opcal to near-IR (e.g., Menéndez-Delmestre+07) àSo, band-shiing from near-IR to opcal does not hamper (significantly) the ability to recognize bars, which becomes important in high-z studies àBand shiing is ONLY an issue when going to shortwards of Balmer break (e.g., Sheth+03)

Galaxy Zoo Sydney 2013 Karín Menéndez-Delmestre 430 D. A. Gadotti

be compromised: the authors mention that their images are not deep the galaxy near the bar end, since it is about this region where the bar enough and the resulting parameters are uncertain. Since their im- isophotes reach their peak in ellipticity, and the bulge component ages are in the near-IR and ours in the optical, and given that galaxies is usually faint there. As the disc of NGC 5850 is very faint, this usually become bluer outwards (but see Gadotti & dos Anjos 2001), dilution is not efficient in this galaxy. the scalelengths obtained here could indeed be somewhat larger These results have implications on previous findings in the lit- than theirs. This systematic difference seems to be present in Fig. 5 erature. For instance, Marinova & Jogee (2007) measured the bar but complicates these comparisons. This difference in wavelength ellipticity via ellipse fits in a sample of 180 barred galaxies. They could also explain the different results for NGC 3227, 4314 and found that only a minority of the bars in their sample have elliptici- 4593, which have significant amounts of dust and star formation ties below 0.4, and that most bars have ellipticities between 0.5 and which certainly haveastronger effect in the optical than in the near- 0.8, with a mean value of about 0.5. As I have just shown, ellipse fits IR. In particular, NGC 4314 has very bright star-forming nuclear systematically underestimate the true bar ellipticity by 20 per cent, spiral arms that show up clearly in the residual image. The light on average. This means that the paucity of weak bars, i.e. those with from these spirals is partially attributed to the bulge component, ellipticities below 0.4, is even more pronounced. Manyof these and, since these spirals should not be so conspicuous in the near-IR, bars in their sample might have higher ellipticities, which, however, this can explain why I obtain a much more massive bulge than Lau- cannot be reliably measured with ellipse fits due to the effects just rikainen et al. On the other hand, it is not clear why our results are discussed. Furthermore, the fraction of bars with high ellipticities discrepant for the bulge of NGC 5701, although the difference in the is, in fact, even higher, as is the true mean value for the ellipticity Sérsic index is within typical 1σ errors. Furthermore, it is unclear of bars. A simple calculation gives a true mean value of around 0.6, if the AGN light should have been taken into account also in their considering an underestimation of 20 per cent. near-IR images. Taken altogether, this general agreement, and the It should be noted that the bar strength does not depend only fact that with the results presented here it is possible to reproduce on the bar ellipticity, but also on its shape (more rectangular, boxy some known results (Figs 2, 3 and 4) are very encouraging. bars, i.e. those with higher c, are stronger) and its mass (see also discussion in Marinova & Jogee 2007, and references therein). The strength of a bar is thus directly connected to the amplitude of the 3.4 The ellipticity of bars non-axisymmetric potential it introduces in the overall potential well To measure the ellipticity of a bar, one usually fits ellipses to the of its host galaxy. With this definition, the strength of a bar does not galaxy image and assumes that the bar ellipticity is that of the most depend on any other of the properties of its host galaxy. On the eccentric fitted ellipse (e.g. Marinova & Jogee 2007). This is a very other hand, the impact of a bar on the evolution of a galaxy depends important parameter because it is strongly related with the strength on other galaxy properties. A strong bar will significantly modify of the bar, and can provide constraints for bar models, like those of the dynamics of gas and stars in a galaxy with a relatively weak e.g. Athanassoula & Misiriotis (2002) and secular evolution scenar- axisymmetric potential, i.e. a galaxy where the bar mass is high ios (e.g. Gadotti & dos Anjos 2001). In Fig. 6, the ellipticity of bars compared to the bulge and disc masses. The same bar would produce as estimated from the image decompositions are plotted against the less significant effects in a galaxy with massive bulge and disc. ellipticity peak in the ellipse fits of GdS06. The latter is used as a Furthermore, since the axisymmetric component of the potential is starting point for the decompositions but the bar ellipticity is a free centrally concentrated, mainly due to the bulge, the changes due to parameter in the fits. It is clear that ellipse fits underestimate the the bar are likely to haveadependence on radius and to be more true ellipticity of the bar. This effect is on average about 20 per cent, significant closer to the bar ends. but it can be as large as a factor of 3. For NGC 5850, however, the match between the two parameters is excellent. Examining the cases 3.5 Disc consumption in NGC 4608 and 5701 where this effect is strongest, as in NGC 4267 and 4303, reveals its origin: the ellipticity of the isophotes in the bar region is diluted It is not uncommon to see in residual images such as those in Fig. 1 by the contribution from the round, axisymmetric component of the regions with evident negative residuals, where the fitted model is nd galaxy. The strength of this effect is thus governed by the difference brighter than the galaxy. In some cases, this is clearly a result of 2 result: bars betweenlook thethinnercontributions inof thebluerbar and thebandsdisc to the total light in dust extinction, butin other cases their presence might mean that the models used are not fully adequate. Inspecting the results in Fig. 1, it is possible to identify two particular cases where such neg- • ε is higher in the opcal 0.8max ative residuals are not only conspicuous, but also clearly delineate bands, compared to the mid-IR a distinct region in the residual image. These are NGC 4608 and N4303 • N4267 5701. In their residual images, one is able to spot a region in the

This result extends to the UV 0.6 N5850 disc where the models are deﬁnitely brighter than the galaxies. It can

bar be described as two crescents, one at each side of the bar, but out of ε BUDDA it (pointed out by the red arrows in Fig. 1). In NGC 4608, these cres- • Driven by bulge sizes: ε 0.4 cents extend to a radius similar to the bar semimajor axis length, i.e. • Bulge looks bigger in redder up to the inner ring surrounding the bar. In NGC 5701, this region 0.2 bands à smaller in the blue Gado+08 is more extended, and the crescents occupy the whole area between the bar and the outer ring. In Gadotti & de Souza (2003), this less lu- - 0.2Limits the size of the bar 0.4 0.6 0.8 Δε ε minous area in the disc component of these galaxies was identified, band-shiing ε max and it was pointed out that the N-body models of bar formation and : 0.05 (up to 0.2) semi-minor axis ellipse evolution presented in Athanassoula & Misiriotis (2002) produce : 0.07 (Figurupe 6 to 0.3) . Ellipticity• ofIn good agreement with bars estimated from image decomposition plotted against the ellipticity peak in ellipse fits from GdS06. Some interesting cases a very similar feature, particularly their models which lead to the are indicated. The solidBUDDA results (Gado+08) line indicates a perfect correspondence. It is clear formation of very strong bars (see their fig. 3). Athanassoula (2002, that ellipse fits systematically underestimate the true ellipticity of the bar. 2003) presents theoretical work which shows that bars get longer The bluer the resrame band, the thinner the bar! Figura 32: Histograma e gráfico de dispersão representando os valores medidos para ⃝C 2008 The Author. Journal compilation ⃝C 2008 RAS, MNRAS 384, 420–439 Galaxy Zoo Sydney 2013 Karín Menéndez-Delmestre aelipticidadedabarrautilizandoométododaelipticidademáxima.

Figura 33: Histograma e gráfico de dispersão representando os valores medidos para ocomprimentodabarrautilizandoométododaelipticidademáxima.

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