Luminous Supernovae
Robert Quimby (Caltech)
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Wednesday, November 10, 2010 Super/Over/Extremely/Very Luminous Supernovae
LSNe
SNe with peak absolute (optical) magnitudes brighter than -21 are Luminous Supernovae (LSNe)
Richardson et al. 2002
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Wednesday, November 10, 2010 SN 2005ap
Quimby et al. 2007 R = 23.5 mag host (not shown) Peak observed mag = 18.1 (unfiltered) Observed light curve rise = 7 days Estimated rise time >20 days?
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Wednesday, November 10, 2010 SN 2005ap Spectra
z = 0.2832 Peak absolute mag = -22.7 (unfiltered) Temperature 17,000-20,000 Line velocities ~20,000 km/s Velocity drops by ~4,000 km/s in 9 days
Quimby et al. 2007 Robert Quimby 4
Wednesday, November 10, 2010 Redshift Distrubution of TSS Supernovae
Quimby et al. 2006
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Wednesday, November 10, 2010 The Mysterious SCP 06F6
Barbary et al. 2009 Robert Quimby 6
Wednesday, November 10, 2010 SN 2006gy
Smith et al. 2008
Peak absolute magnitude nearly -22
Brighter than -21 mag for ~100 days
Integrated light >1051 erg
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Wednesday, November 10, 2010 Pair-Instability SNe
First Proposed it the 1960’s (Rakavy et al. 1967; Barkat et al. 1967) Massive stars are supported by radiation pressure At high temperatures, photons are created with E > e+e- Losses to pair production soften the EOS, and lead to instability Expected fate of the first (low metal, high mass) stars
Waldman 2008
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Wednesday, November 10, 2010 SN 2006gy Late-Time Light
CurveNo. 6, 2010 NEW OBSERVATIONS OF THE VERY LUMINOUS SUPERNOVA 2006gy 2223
1011 >400 days. The early-time measurements (< 250 days) come from Smith et al. (2010). The optical measurement near day
) 400 comes from photometric measurements by Kawabata et al. • O 10 (2009), while the optical luminosity on day 810 comes from a 10 Total Luminosity NIR Luminosity direct integration of our HST observations (see Section 3.3.1). Optical Luminosity The three late-time NIR luminosities represent lower limits based on the measured K#-band flux (see above, Section 3.2). 9 56 1 10 The decay rate of Co, 0.98 mag (100 day)− ,ismuchfaster than the observed decay of the K# flux from SN 2006gy, 1 0.2 mag (100 day)− . The late-time NIR excess declines at ∼ 56 108 aratethatistooslowtobeexplainedby Co heating alone. The PISN model of Nomoto et al. (2007), which provided Bolometric Luminosity (L
56 good agreement with the early-time light curve of SN 2006gy 2.5 MO • Ni 107 after an artificial reduction of the total ejecta mass from their evolutionary calculation, was able to reproduce the late-time 0 200 400 600 800 Days since explosion NIR luminosity observed by Smith et al. (2008b). This model required less than 100% efficiency in the conversion of gamma- Figure 5. Evolution of the bolometric luminosity of SN 2006gy during the first Miller et al. 2010 800 days after explosion. Optical data are shown as black circles, and NIR data rays (from radioactive decay) to optical/NIR emission, which are red squares. Early-time data (< 250 days) are from Smith et al. (2010). means that the light curve should decay faster than 0.98 mag Robert Quimby 1 9 The optical detection near day 400 is from Kawabata et al. (2009). All other (100 d)− . The possibility of a PISN was first invoked to explain Wednesday, November 10, 2010 data are from this work. NIR measurements are only lower limits to the total the large peak luminosity of SN 2006gy (Ofek et al. 2007;Smith IR luminosity, because our observations do not sample redward of 2.2 µm(see et al. 2007). This scenario would have required the production the text). The dashed line shows the expected decline if the luminosity were 56 powered by 2.5 M of 56Ni. The flat nature of the light curve indicates that of ! 10 M of Ni, which in turn would produce a large ! 56 radioactivity is not! the primary energy source for the late-time emission. late-time luminosity that decays at the rate of Co. The late- (A color version of this figure is available in the online journal.) time NIR luminosity is not accounted for in either the general PISN models or the artificial model of Nomoto et al. (2007); it therefore provides a serious challenge to the PISN hypothesis.12 dust with T 600 K11 could dominate the IR emission, in which case the≈ luminosity could be significantly higher than the 3.2.2. Collisional Heating of the Dust values quoted above. The location of this dust, and whether it is newly formed Another possibility is that the dust existed prior to the or pre-existing at the time of the SN explosion, remain to SN explosion, at large distances from the explosion site, and be determined. The dust-cooling time is short, meaning that was heated via collisions with the expanding material in the aprolongedheatsourceisneededtoexplaintheextended expanding blast wave. The intense UV/optical output from an excess. We consider four possibilities for heating the dust: (1) SN at its peak vaporizes any dust in the vicinity of the SN (Dwek radioactive heating from 56Co decay, (2) collisional excitation 1983). This radiation near peak creates a dust-free cavity into of pre-existing dust, (3) heating via radiation from circumstellar which the SN ejecta may expand at early times; however, the interaction, and (4) a late-time IR dust echo, where pre-existing ejecta blast wave will eventually reach the edge of the dust-free dust is heated by the radiation produced while the SN was near cavity, at which point collisional excitations of the dust may its optical peak. generate NIR emission. The large peak luminosity of SN 2006gy, 8 1010 L (Smith 3.2.1. Radioactive Heating from 56Co et al. 2010), provides significant challenges× to this collisional! heating scenario. Dwek (1983)showsthattheradiusofthedust- Smith et al. (2008b)notedthattheobservedK#-band de- free cavity can be determined from the peak luminosity and the cay between 2007 September and 2007 December could be dust vaporization temperature, assuming the grain emissivity explained with radioactive heating from a minimum of 2.5 M Q is proportional to (λ/λ ) 1: of 56Ni, if a sufficient amount of dust formed in order to move! v 0 − the luminosity into the NIR (though they favored another inter- 0.5 Qν L0(L ) pretation; see below). We show the bolometric evolution of R1(pc) 23 ¯ ! , (2) = λ (µm)T 5 SN 2006gy through the first 800 days post-explosion, in- ! 0 v " cluding both optical and NIR∼ detections, in Figure 5.From where R is the radius of the dust-free cavity, Q is the mean Equation 19 of Nadyozhin (1994), and the fact that the lumi- 1 ¯ ν 56 56 T nosity from Co decay dominates over Ni decay at times ! 2 grain emissivity, L0 is the peak luminosity, and v is the dust weeks after explosion, we arrive at the following expression for vaporization temperature. Following Dwek (1983), if we assume 18 Qν 1andthatλ0 0.2 µm, we find that R1 1.4 10 cm, the radioactivity-powered luminosity of an SN, assuming 100% ¯ = = ≈ × trapping of gamma-rays: for a vaporization temperature Tv 1000 K. If the absorption ≈ 2 coefficient is instead proportional to λ− ,thenthecavity 43 t/(111.3d) 1 L56Co 1.45 10 exp− MNi/M erg s− , (1) becomes even larger. Based on the observed width of the Hα = × ! line from SN 2006gy, Smith et al. (2007)estimatethespeedof 1 where t is the time since SN explosion in days and MNi is the the blast wave to be 4000 km s− , which would mean that this total mass of 56Ni produced. Using Equation (1)wealsoshowin material would take 112 yr to reach the edge of the dust-free Figure 5 the expected light curve from 2.5 M of 56Ni at times cavity. Even if there∼ are ejecta traveling at more typical SN ! 11 Smith et al. (2008b) show that the combination of the peak luminosity and 12 The pulsational pair-instability model of Woosley et al. (2007) has not, distance to the dust suggests an equilibrium temperature around 600 K. however, been excluded; see also Smith et al. (2010). SN 2006gy Spectra
Smith et al. 2010
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Wednesday, November 10, 2010 SN 2007bi: The PISN Case Gal-Yam et al. 2009 al. et Gal-Yam
Optical light curve decay rate consistent with the production 56 of ~7 M of Ni Iron abundance in nebular spectra also consistent with the 56 decay of ~4-7 M of Ni
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Wednesday, November 10, 2010 SN 2008es
Gezari et al. 2009; see also Miller et al. 2009
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Wednesday, November 10, 2010 2009: PTF Finds LSNe
PTF09cwl PTF09cnd PTF09atu Before After
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Wednesday, November 10, 2010 LSNe (Candidates) from PTF
Name Notes LSN-Ic LSN-IIn PTF09uy LSN-IIn Bright BL-Ic PTF09atu LSN-Ic PTF09cnd LSN-Ic PTF09cwl LSN-Ic PTF10bfz BL-Ic PTF10bjp LSN-Ic 10% PTF10cwr LSN-Ic PTF10fel LSN-IIn PTF10heh LSN-IIn PTF10hgi LSN-Ic PTF10jwd LSN-IIn 50% PTF10nmn LSN-Ic 40% PTF10ooe BL-Ic PTF10qaf LSN-IIn PTF10qwu LSN-IIn PTF10scc LSN-IIn PTF10tpz LSN-IIn? PTF10uhf LSN-Ic PTF10xee LSN-Ic? PTF10vqv LSN-Ic Observed numbers--not volumetric rates!
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Wednesday, November 10, 2010 LSN-Ic Spectra
Quimby et al. 2010
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Wednesday, November 10, 2010 PTF09cnd: Spectal Comparison (near r- band maximum)
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Wednesday, November 10, 2010 LSN-Ic Light Curves
Quimby et al. 2010
Absolute V-band Magnitude
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Wednesday, November 10, 2010 PTF09cnd: Late-Time Photometry
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Wednesday, November 10, 2010 PTF09cnd: Late-Time Spectra
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Wednesday, November 10, 2010 Summary of the Observations
There are observationally distinct (but perhaps still physically related) groups of LSNe Rise times are typically ~50 days, but not always well constrained and not always the same LSN-Ic lack metal lines through maximum light (temperature or composition effect?) LSN-Ic photospheres persist for ~6 months past maximum light Some LSN-Ic show slow photometric declines, consistent with a large production of 56Ni, others must produce far less
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Wednesday, November 10, 2010 Power Sources 1 Radioactive Decay
Energy released by the radioactive decay of elements synthesized in the explosion (e.g. 56Ni) is thermalized and re-raidiated
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Wednesday, November 10, 2010 Power Sources 2 Recombination
SN 2006bp (Type II-P)
Quimby et al. 2007
Material ionized by the blast wave recombines, releasing stored energy Robert Quimby 22
Wednesday, November 10, 2010 Power Sources 3 Interactions
Ejecta run into surrounding material
(progenitor wind, shells, etc.) Smith et al. 2008
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Wednesday, November 10, 2010 PTF09cnd: BB Comparison
SN 2008D • Discovered by SWIFT during shock breakout (Soderberg et al. 2008) • Type Ib/c
• Compact progenitor (R ~ R) SN 2008es • Discovered by ROTSE-III (Gezari et al. 2009)
• Type II (very luminous, Mpeak < -22)
• Likely extended progenitor (R > 5000 R)
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Wednesday, November 10, 2010 Shell Scenario
outer shell expanding at a few 1000 km/s energy injected from with in
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Wednesday, November 10, 2010 Pulsational Pair-Instability SNe
Woosley et al. 2007
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Wednesday, November 10, 2010 2 Kasen & Bildsten
until the remnant is as old as the effective diffusion time 1/2 td ∼ (κMej/vtc) ,whereκ is the opacity, after which -10 ) the entropy is lost. Such thermally powered light-curves -3 -11 2 (e.g. Type IIp’s) have a luminosity Lth ∼ Esnte/td.The -12 large amount of adiabatic expansion that has occurred -13 by the time t ∼ td leads to low luminosities. " -14 Now consider the impact of late time (t te)en- density (g cm
10 -15 ergy injection from a young magnetar with radius Rns =
log -16 10 km and initial spin Ωi =2π/Pi.Themagnetarrota- tional energy is 3.0 K) E = 0.1 4 2.5 p 2 Ep = 0.2 InsΩi 50 −2 2.0 E = 0.4 2 E = =2× 10 P ergs, Kasen(1) & Bildsten p p 10 E = 1.0 2 1.5 p Ep = 2.0 until the remnant is as old as the effective diffusion time 1.0 where P10 = Pi/110/2 ms and we set the NS moment of in- td ∼ (κMej/vtc) ,where45 κ2 is the opacity, after which -10 ertia to be I =10 gcm.Thismagnetarlosesrota- ) 0.5 -3
ns temperature (10 the entropy is lost. Such thermally powered light-curves -11 tional energy at the rate set by magnetic dipole radiation2 0.0 (e.g. Type IIp’s) have a luminosity Lth ∼ Esnte/td.The -12 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 (with the angle, α,betweenrotationandmagneticdipole 9 large amount of adiabatic expansion that has occurred velocity coordinate (10 cm/s) fixed at sin2 α =1/2), injecting most of the energy into -13 by the time t ∼ td leads to low luminosities. Fig. 1.— Radiation-hydrodynamical calculations of the density the expanding remnant on the spin-down timescale" -14 Now2 consider the impact of late time (t Kasente)en- & Bildsten density (g cm (top) and temperature (bottom) of magnetar energized supernovae,
10 -15 ergy injection from a young3 magnetar with radius Rns = one month after the explosion. The supernova had Mej =5M! 6Insc −2 2 log -16 51 5 10 kmuntil and the initial remnantt = spin is asΩ oldi =2 as=1 theπ/P.3 eBiff.Themagnetarrota-ectiveP diyrffusion, time (2) and Esn =10 ergs. The magnetar had tp =10 sec and various p 1/22 6 2 14 10 3.0 51 td ∼ (κMej/vtc)B ,whereR Ω κ is the opacity, after which -10 values of E ,labeledinunitsof10 ergs. The dashed line in tional energy is ns i ) p K)
-3 E = 0.1 the entropy is lost. Such thermally powered light-curves -11 4 the2.5 top panel shows the unperturbed density structure,p takenfrom 14 2 2 Ep = 0.2 where(e.g.B Type= B/ IIp’s)10I havensΩG. a luminosity To inputL thisth−∼ energyEsnte/td.The at a time -12 Equation (5). 14 i 50 2 2.0 Ep = 0.4 large amountEp = of adiabatic=2 expansion× 10 P10 thatergs has, occurred (1) tp ! td requires a minimum B field of -13 Ep = 1.0 by the time t ∼ t 2leads to low luminosities. 1.5 d -14 Ep = 2.0 − " shell1.0 near the leading shock, leaving the hot, low den- whereNowP10 consider= Pi/10 the ms14 impact and we of−1 set/ late4 the time NS3/8 (t moment1/8 te)en- of in- density (g cm B>1.8 × 10 P10 κ M E G, (3) 10 -15 ergy injection from45 a young2 magnetares 5 with radius51 Rns = sity0.5 interior evident in the 1-D radiation hydrodynam-
ertia to be I =10 gcm.Thismagnetarlosesrota- log ns -16 temperature (10 Magnetar10 km and initialModel spin Ωi =2π/Pi.Themagnetarrota- 2 −1 ical0.0 calculations of Figure 1. In multi-dimensional cal- wheretionaltionalκ energyes energy= κ at/0 is. the2cm rateg set, byM magnetic5 = Mej/5 dipoleM" and radiationE51 = 3.0 K) culations0.0 0.2 of pulsar0.4 wind0.6 nebulae,0.8 E =1.0 0.1 Rayleigh-Taylor1.2 1.4 insta- − 4 p (with the51 angle,1 α,betweenrotationandmagneticdipole 2.5 9 Esn/10 ergs .Therequiredfieldsareinthemagnetar2 velocity coordinate (10Ep = cm/s)0.2 2 InsΩi 50 −2 bilities broaden the shell and mix the swept-up material fixed at sin α =1/2), injecting most of the energy into 2.0 Ep = 0.4 range. This lateEp time= entropy=2× injection10 P10 ergs resets, the(1) interior Fig.(Jun 1.— 1998;Radiation-hydrodynamical Blondin et al. 2001).E calculationsp = 1.0 of the density the expanding remnant2 on the spin-down timescale 1.5 energy scale to Eint ∼ Ep and overwhelms the initial (top) and temperature (bottom) of magnetarEp = 2.0 energized supernovae, where P = P /10 ms and we set the NS moment of in- 1.0 The bubble expansion will freeze out in Lagrangian thermal energy10 wheni E3p >Esn(te/tp). Thus even low one month after the explosion. The supernova had Mej =5M! ertia to be I =106I45nscgcm2.Thismagnetarlosesrota-−2 2 0.5 coordinates51 when the leading shock5 velocity becomes ns temperature (10 and Esn =10 ergs. The magnetar had tp =10 sec and various magnetar energiestp = Ep