1. Core-collapse supernovae as dust producers: what Spitzer is telling us
Rubina Kotak (Queen’s University Belfast)

2. Outline: Why core-collapse supernovae as dust producers?
Model predictions
Observational evidence
Recent examples
Dust mass estimates from SNe
SNe as dust destroyers
Open issues

3. Core-collapse SNe: major source of cosmic dust?
Cernushi et al. (1967), Hoyle & Wickramasinghe (1970), Clayton (1979), Gehrz (1989), Tielens (1990), Dwek (1998), Todini & Ferrara (2001), Nozawa et al. (2003), …
Growing interest as a source of dust at high-z
Reddening of background quasars by damped Ly systems FIR emission from DLAs
Gas-phase Zn/Cr ratios
Detection of far-IR and mm emission from quasars and galaxies at 6.5 > z > 1
--> 107~108 M of dust

4. Dust at high redshifts The case of SDSS J1148+5251 z ~ 6.4:
Smail et al. (1997), Hughes et al. (1998), Omonti et al. (2001,2003), Bertoldi et al. (2003), Maiolino et al. (2004), Robson et al. (2004), Beelen et al. (2006) + …
The case of SDSS J z ~ 6.4:
Age : 400 Myr (age of Universe ~ 890 Myr)
Gas mass : 3x1010 M
Dust mass: 2x108 M
SFR : Myr-1
Rapid metal and dust enrichment of the ISM.
enrichment due to AGB stars too slow
CCSNe good candidates
Fan et al. (2003)
Dwek et al. (2007)

5. Carbon stars as dust producers at low metallicity?
Carbon star (possibly) in Sculptor Galaxy: Z = 0.04 Z(Milky Way)
At high redshifts, intermediate mass stars could form as soon as trace quantities of metals appear in the ISM => precursors of carbon stars could form relatively early.
Require only ~400 Myr to reach AGB.
BUT:
-- How much carbon dust? (C dredge-up certain)
-- SFR + IMF - dependent
Sloan et al. (2009)

6. dust producers dust destroyers
CCSNE
dust producers
dust destroyers
Suitable materials: C, O, Mg, Al, Si, Fe
Cooling: expansion + molecules
hostile environment (UV, )
thermal sputtering
grain-grain collisions …

7. Models predict 0.1 < M dust < 1 M per SN a few years after explosion
e.g. Todini & Ferrara (2001), Nozawa et al. (2003), Nomoto et al. (2006)
E.g. if all the refractory elements in a 25 Msun SN condensed into dust, then get 1 Msun of dust.
Todini & Ferrara (2001)

8. What is the observational evidence?

9. Detecting dust in supernovae:
Attenuation of spectral line profiles

10. [OI] line profiles in Type IIpec SN 1987A at 529 and 738 days post-explosion
Danziger et al. (1991)

11. [OI] line profile in the type II-P SN 2004dj at ~900 days
SN spherically symmetric distribution of optically-thin gas. Dust is represented by an opaque disk centred on the los with the flat surfaces parallel to this direction.
[OI] line profile in the type II-P SN 2004dj at ~900 days

12. SN 1998S (type IIn): ejecta/CSM interaction,
Dust formation in a cool dense shell behind the shock front.
Pozzo et al. (2004)

13. Detecting dust in supernovae:
Attenuation of spectral line profiles
Thermal emission of dust grains
Until 2003, ~13 cases of core-collapse SNe showing near-IR excesses
BUT,
-- new dust condensing in SN ejecta, or
-- IR-echo due to pre-existing circumstellar dust?

14. INFRARED ECHO LIGHTCURVES

15. IR ECHO OR NEW DUST? Monitoring
(Echo earlier + brighter)
Bouchet et al. 1989, 93 Meikle et al 2006

16. Do all core-collapse SNe form dust?
How much dust?
When does dust form?
Under what conditions?
Molecules a necessary intermediate step?
Will it survive?
What is the composition, grain size?
How does dust production vary with SN subtype?
What is the influence (if any) of the environment? …

17. To assess the ubiquity of dust formation in core-collapse supernovae need:
Sample of well-observed “normal” SNe
(photometry + spectroscopy)
Mid-IR monitoring extremely challenging from the ground.
--> No mid-IR studies of SNe since SN 1987A

18. Detection of SiO SiO ~ 2x10-4 M Liu & Dalgarno model.
SN 2005af (type IIP)
SiO ~ 2x10-4 M
Liu & Dalgarno model.
Kotak et al. (2006)

19. Isothermal dust model
Simple analytical model comprising a uniform sphere of isothermal dust grains (Lucy 1989; Osterbrock 1989)
Free parameters: (for a given grain composition)
grain temperature,
sphere radius,
grain number density scaling factor
Guided by dust condensation calculations based on SN explosion models e.g. Kozasa et al. 1989, Todini & Ferrara (2001), Bianchi & Schneider (2007)
Assume that dust of uniform no. density forms throughout the zone containing abundant refractory elements. Extent of this zone from nebular spectra ~ 2500 km/s

20. SN 2005af (II-P)
Spitzer IRAC μm 576d
Age Temp. Md f (d) (K) (10-4 M)

21. Case study: SN 2004et (type II-Plateau)
Extensive set of optical + mid-IR data for the most common type of core-collapse SN ---> evolution of SED

22. SED evolution: evidence for increasing emission due to dust
3-component black-body fits for days :
Hot: K
--> ejecta
Warm: K
--> newly formed dust
Cold: K
--> pre-existing dust
NB: no attempt was made to match the broad emission feature / lines
Optical data from Sahu et al. (2006)

23. Hot component: ~5000-7000 until 800d. Rise in temp. at last 2 epochs
Warm component: d cooled and faded monotonically; BB surface never exceeded 1600 km/s => consistent with warm emission arising from newly-formed dust. Disfavour echo because a) would require a contrived cavity size b) line-shifts seen in the optical c) decline in optical light curve accelerated
Cold component: roughly constant temperature throughout. High velocities rule out newly-formed dust

24. Example IDM fit: day 464 evidence for newly formed silicate dust
SiO + silicate grains
Amorphous carbon grains

25. Silicate dust model fits
Temp (K)
900
650
400
 (10µm)
2.8
3.6
11.5
M(SiO) Msun
5.7
3.7
~0.5
M(dust) Msun
0.39
0.66
1.5
Fading of silicates 690+ d due to
Increasing optical depth as more dust forms
Increasing contribution from non-silicate dust (e.g. CDS)
Silicate feature yields an additional constraint at each epoch => in spite of high , dust mass estimates are not just lower limits

26. The disappearance and reappearance of 04et
3.6µm
Pre-explosion
1222 d
795 d
300 d

27. Cause of mid-IR rebrightening: ejecta/CSM collision
Dust formation in a cool dense shell behind the reverse shock. 10 km/s RSG wind at ~6000 AU
Wide boxy profiles + decrease from blue to red => dust

28. Origin of cold infrared source
Echo from pre-existing dust?
Applying an IR echo model
=> dust had to lie 10 pc from SN,
=> dust mass of 350 Msun (to reproduce luminosity)
=> cannot be due to the progenitor of SN 2004et
More natural explanation: IR interstellar echo -- predicted by Wright (1980); Bode & Evans (1980), but never observed.
For 04et, the cold component is well-fit by a single set of parameters from d.
Prediction: for a cavity of 10pc, expect constant IR luminosity for ~65 yrs.

29. The multi-faceted nature of SN 2004et
Evidence for freshly condensing silicate dust
Very-late time ejecta - circumstellar medium interaction => dust in cool dense shell
Cold infrared component => IR echo from interstellar dust
Disentanglement difficult!

30. Recent claim of a large dust mass in SN 2003gd (IIP)
0.02 M of dust -- Sugerman et al. (Science, 2006)
Sugerman et al. (2006) Meikle et al. (2007)
3.6-8m/~700d upper lts. only m: 737 Jy
24m /~700d   Jy
(same data)
8m difference
24m
670d

31. Recent claim of a large dust mass in SN 2003gd (IIP)
Sugerman et al. (2006)
0.02 M of dust -- Sugerman et al. (Science, 2006)
Sugerman et al. (2006) Meikle et al. (2007)
24m /~700d   Jy
Error in 24m /~700d flux of Sugerman et al.
Outer limit of dust-forming zone > metal line velocities from late-time spectra (~2000km/s)  unphysical
Total luminosity > 4 x total radioactive luminosity deposited in ejecta
 severe energy deficit
Similar decline rates c.f. 87A, but invoke vastly different efficiencies
Directly detected dust: SN 2003gd produced no more than few 10-5 M
For details see Meikle et al. (2007)

32. Summary of SN dust mass estimates
Type
Dust mass (Msun)
Technique
Ref.
1987A
II-Pec
7.5x10-4
mid-IR + opt. line attenuation
Ercolano et al. (2007)
1998S
IIn
>2x10-3
optical + near-IR line attenuation
Pozzo et al. (2004)
2006jc
Ibn
3x10-4
near-IR + line attenuation
Mattila et al.; Sakon et al., Smith et al.
1999em
II-P
~10-4
optical line attenuation
Elmhamdi et al.
2003gd
4x10-5
mid-IR
Meikle et al. (2007)
2004et
Few x 10-4
mid-IR + line attenuation
Kotak et al. (2009)

33. Dust mass estimates from supernova remnants
CasA:
3x10-3 Msun (Hines et al. 2004) at 80K
Msun (Rho et al. 2008)
2Msun Dunne et al. (2003); Krause et al. (2004) 0.2< Msun: sub-mm
~10-4 Msun (Dwek et al.): Fe needles; but Dunne et al. (2009): sub-mm polarization: Msun if 100% efficiency of dust condensation
SNR 1E :
8x10-4 Msun (Stanimirovic et al. 2005) Msun (Rho et al. 2009)
Crab, Kepler
(Tenim et al. 2006, Blair et al. 2007);
1 Msun (Morgan et al. 2003); Msun (Gomez et al. 2009): sub-mm

34. Dust Composition Cas A (Rho et al. 2008)
1st type Dust: 21mm-peak dust; Mg proto-silicate, amorphous (am) MgSiO3, am SiO2, FeO, and aluminum oxide (Al2O3). The compositions suggest the dust forms around inner-oxygen and S-Si layers.
Total dust mass of 0.02 to Msun
(depending on dust composition)
Featureless Dust
Fe, C, Al2O3 (FeO)

35. Dust mass estimates from supernova remnants
CasA:
3x10-3 Msun (Hines et al. 2004) at 80K
Msun (Rho et al. 2008)
2Msun Dunne et al. (2003); Krause et al. (2004) 0.2< Msun: sub-mm
~10-4 Msun (Dwek et al.): Fe needles; but Dunne et al. (2009): sub-mm polarization: Msun if 100% efficiency of dust condensation
SNR 1E :
8x10-4 Msun (Stanimirovic et al. 2005) Msun (Rho et al. 2009)
Crab, Kepler
(Tenim et al. 2006, Blair et al. 2007);
1 Msun (Morgan et al. 2003); Msun (Gomez et al. 2009): sub-mm

36. Molecules in SN ejecta
2004dj (IIP) et (IIP)

37. Dust formation in all CCSNe? (Probably) yes for IIPs
When does dust form? in IIPs, > few 100d
Under what conditions? Molecules always necessary?
all IIPs in our sample (6) show CO; some show SiO before few 100d (previously only seen in 1 SN: ‘87A)
How much dust?
Currently M of dust i.e x lower than needed.
-- much more may exist in optically-thick clumps
-- more modelling effort required
How does dust production vary with SN subtype?
-- currently, only few examples of other types:
SN 1987A (II-pec), SN 1990I, 06jc (Ib), SN 1998S (IIn), …