A Spitzer-IRS view of early-type in the Revised Shapley-Ames Catalog

Roberto Rampazzo Composite mul- λ Team : A. Bressan (SISSA), F. Annibali (OaBO), L. M. Buson, M. Clemens, A. Marino & P. Mazzei (INAF OAPD), P. Panuzzo (Obs. Paris Meudon), G. Trinchieri & A. Wolter (INAF-Brera), O. Vega (INAOE), W.W. Zeilinger (IfA, Univ. Wien) introduction

ETGs (Es+S0s) may show the presence of a young stellar component! Rejuvenation in optical (… Longhetti et al 2000; Annibali et al. 2007) ! in Far UV (e.g. Rampazzo et al. 07; Schawinsky et al. 2007; Marino et al. 2010, 2011) Rejuvenation also in the outer regions! in rings, along the bar, associated with AGN... introduction Drivers seem of gravitational origin external inner accretions, secular merging evolution Trace recent phases of ETGs assembly history

this talk concentrate on the ETGs nuclear region ! Why a mid infrared view ? OPTICAL

NGC 3258

NGC 5813

Rampazzo et al. (2005), Annibali et al. (2006, 2007, 2010 ) Why a mid infrared view ?

MID INFRARED

NGC 3258

NGC 5813

Panuzzo et al. (2011) Why a mid infrared view ?

• Age and metallicity have the same effect in the optical region • Age and metallicity have opposite effect in the mid infrared region • Combining optical and MIR removes the age- metallicity degeneracy • Note that the MIR alone still suffers from degeneracy 3 samples investigated with Spitzer-IRS

! The sample 18 ETGs (PI Bressan) ! characterizing passive ETGs The field sample 40 ETGs (PI Rampazzo) ! characterizing ETGs activity The Revised Shapley-Ames sample 91 ETGs (Rampazzo et al. 2013, SHA) towards a systematics MIR spectra of Virgo ETGs Bressan et al. (2006, ApJ, 39, L58)

• We observed with IRS- Spitzer 18 galaxies in Virgo • We demonstrated for the first time the presence of predicted bump at 10µm in early type galaxies • The 10µm emission feature is very similar to observed AGB outfows (Molster et al. 2000) and to Bressan et al. (1998) SSP models • ¾ of the galaxies show passive spectra (i.e. no emission lines, no PAHs) Activity in Polycyclic Aromatic Hydrocarbons

1/4 of Virgo ETGs observed by Spitzer-IRS show signature of activity ! 3 (NGC 4435, NGC 4550, NGC 4636 show PAHs) The field sample: spectral classification

passive ETGs vs. SSP models

Silicate emissions The field sample: spectral classification

Class 4: AGN (5%)

Class 3 : star forming (7,5%)

Class 2 : anomalous PAHs (50%) Class 1: passive with lines (17%)

Class 0: passive (20%)

More than 3/4 are active in the field ! The RSA sample 91 ETGs (out of 363) 56 Es (E0-E6)

Rampazzo et al. (2013, MNRAS ) 8 mixed E/S0+S0/E 27 S0s (SB0/Sa+SB0/SBa) Refining MIR classes

class 3

class 4 Refining MIR classes

12 Gyr - Z SSP ⊙ Taxonomy

passive (E S0s) +11 +11 46−10 % 20 − 7 % with emissions +12 64−6 % with PAHs +8 47−7% star forming +4 9−3% H2 ETGs PAH from carbon stars ? No ionized PAHs features i.e. not powered by SF Post starburst (300Myr - 1.3 Gyr) objects? in + 10 % of Es and + 15 % of S0s. Vega et al. (2010) H 2 34 − 8 51−12 Evolutionary scenario ?

t0

class 2

class 3

t1 < 1 Gyr class 4 Panuzzo al. (2011, A&A, 528, A10) Rampazzo et al. (2010, MNRAS, 432, 474) Some conclusions …

+7 The nucleus of 36 − 6 % of nearby ETGs in our MIR atlas are passive (class-0). Class-0 ETGs set the lower boundary of the P(1.4 GHz) radio power. +22 78 − 18 % show no dust-lanes in the optical, although some show morphological and kinematical distortions pointing to a past accretion episode. Class-0 ETGs include either genuinely unperturbed, passively evolving galaxies or systems in which the effect of accretion has already quenched.

+12 64 − 6 of nuclei show emission lines. The detection of emission lines in galaxies showing kinematical evidence of merger events argues against the so-called ‘dry mergers’ being an important formation mechanism for ETGs. ! +10 +15 H 2 in 34 % of Es and 51 % of S0s. S0s more active than Es ! ! −8 −12 PAHs are detected in 47 + 8 % of ETGs. ! −7 Only a small fraction are star forming: 9 + 4 %. ! −3 The ratio between class-3 and class-2 ETGs is consistent with being produced by a episode with typical lifetime of 200 Myr.

Kinematical and/or morphological scars of recent accretions are found in + 8 41−7% of our ETGs, even in passively evolving galaxies further supporting the view of an evolutionary link between MIR classes and accretion/feedback phenomena. What about new ETGs classifications? Spitzer aperture 3.6”x18”

core profiles ! dry mergers

cusp profiles ! wet mergers

Kormendy et al. (2009, ApJSS, 182, 216) core vs. cuspy ETGs ?

core

cuspy

NGC 4374

NGC 4382 core vs. cuspy ETGs ? NGC 4486

• The MIR SED of M87 can No torus emission found be decomposed into: Emission lines are not – a stellar component with present in the jet AGB feature – a pure power-law synchrotron component

SL1

LL2 Buson al. (2009, ApJ, 705, 356) core vs. cuspy ETGs ?

Cuspy ETGs fainter than MK=-24 in the Virgo and Fornax clusters show predominantly passive nuclear spectra.

Virgo+Fornax

cuspy Virgo+Fornax+ field What about fast vs. slow rotators ETGs ? Dissipative merging (``wet’’ merging) are the way to (re)-build a fast rotating disk-like component ! Khochfar et al. (2011, MNRAS, 417, 845) SR are unable to (re)-build a fast rotating component since they exhausted their gas since their last ``wet merger” happened at z> 1.5 Gyr. What about fast vs. slow rotators ETGs ?

fast rotators class 3 class 0 class 2 class 4 cuspy xclass 1 core

slow rotators Further conclusions …

We find that the MIR spectral classes are unrelated to cuspy/core and fast(FR)/ slow (SR) kinematical class within re/2. PAH complexes as well as molecular and atomic emission lines are found with comparable frequencies in the nuclei of ETGs of both photometric and kinematical classes ! Cuspy ETGs fainter than MK=-24 in the Virgo and Fornax clusters show predominantly passive nuclear spectra (most with a4/a positive !). ! If MIR spectral classes are sensitive to the evolution of ETGs within the last < 1Gyr, then the cuspy/core and SR/FR classes are the results of more ancient evolution. !