Multiwavelength Observations of Dust-Obscured Galaxies Revealed by Gamma-Ray Bursts

Transcription

1 Multiwavelength Observations of Dust-Obscured Galaxies Revealed by Gamma-Ray Bursts Hubble Fellow Caltech, Department of Astronomy IPAC Seminar

2 Collaborators Brad Cenko Joshua Bloom Adam Morgan Nial Tanvir Andrew Levan Hsiao-Wen Chen Jason Prochaska Nat Butler Maryam Modjaz Rick Perley Shri Kulkarni Jens Hjorth Johan Fynbo Daniele Malesani Thomas Krühler UC Berkeley UC Berkeley UC Berkeley Univ. of Leicester Univ. of Warwick Univ. of Chicago UC Santa Cruz Univ. of Arizona New York Univ. NRAO Socorro Caltech DARK Cosmology Centre DARK Cosmology Centre DARK Cosmology Centre DARK Cosmology Centre

3 Outline Gamma-Ray Bursts Motivation Where are the dust-obscured GRBs? Pre-Swift host galaxy results Dark Bursts Dark GRB afterglows and dust extinction Dark GRB host galaxies

4 Gamma-Ray Bursts

5 (Long) Gamma-Ray Bursts

6 GRBs: Massive Stellar Core-Collapse

7 Lighthouses for the High-z Universe GRB B: MR = -39 mag at peak GRB : redshift z = 8.3

8 Probes of High-z SFR Prochaska et al Robertson & Ellis 2011

9 Probes of High-z SFR BUT Prochaska et al Robertson & Ellis 2011

10 Morphology Differences GRB hosts SN hosts Fruchter et al. 2006

11 Redshift Differences Robertson & Ellis 2011 See also Kistler et al. 2008, Kistler et al. 2009, Butler et al. 2009

12 Color Differences LeFloch Smail et al. 2004, Temporin et al. 2008, Mobasher et al. 2007, Shapley et al. 2001

13 Color Differences LeFloch Smail et al. 2004, Temporin et al. 2008, Mobasher et al. 2007, Shapley et al. 2001

14 SED Differences Data from grbhosts.org SN host HST image at 2 months Fruchter et al Host of GRB at z = 0.17: No detection at 2.2 μm, 3.6 μm, 5.8 μm... Wavelength (μm)

15 Data from grbhosts.org SED Differences host complex HST image at 2 months Fruchter et al Host of GRB at z = 1.60: No detection at 2.2 μm, 3.6 μm, 5.8 μm... Wavelength (μm)

16 Mass/Luminosity Differences Pre-Swift IRAC 3.6/4.5 μm Imaging

17 Mass/Luminosity Differences Luminous, obscured galaxies dominate at z> % Contribution to total SFR LIR 0% (10 11 L o (LI R <L IR < ULIRGs > 1012 Lo) L) o Normal galaxies (LI R < 1011 Lo) Typical GRB redshift range 0 1 Modified from Perez-Gonzales et al Gs Redshift 2 (model assuming α=-1.7)

18 Metallicity Differences Modjaz et al. 2008

19 GRBs: a Biased Tracer? Stanek et al. 2006, Wolf & Podsiadlowski et al. 2007, Modjaz et al. 2008, Metallicity cut-off ZGRB < Z Sol ar ~ But, c.f. Savaglio et al. 2008, Chen et al. 2009, Kocevski et al. 2010, etc.

20 Optical Selection Biases Identification of the host galaxy requires accurate afterglow position! ~1-2 or better: Narrow-field X-ray UV/optical Infrared Radio Swift X-ray error circle (2 ) optical position (0.2 ) gamma-ray error circle (60 )

21 Optical Selection Biases Identification of the host galaxy requires accurate afterglow position! ~1-2 or better: Narrow-field X-ray UV/optical Infrared Radio Not commonly available pre-swift (before 2005) Not commonly available pre- or post-swift (<20% of GRBs)

22 Dark Bursts GRB B at ~200 sec Some GRBs have exceedingly faint optical afterglows. R > 20 mag R = 10 mag X-ray position of GRB A at ~200 sec

23 Direct Evidence for Extinction Modified MW-like dust Av,rest = 3.3 ± 0.4 mag AR,obs = 5.8 ± 0.7 mag Perley et al. 2010b

24 Indirect Evidence for Extinction X-r ay Optic al lim Xra y its

25 Indirect Evidence for Extinction z<4 z = 1.35 ± 0.25 Xra y z = 2.1 z<4

26 Extinction Distribution Many (but not most: ~20%) GRBs are highly extinguished. ~8-25% of Swift GRBs have Av>1 mag Perley et al Kruehler et al ~5-15% have Av>2 mag

27 Extinction Distribution Many (but not most: ~20%) GRBs are highly extinguished. ~8-25% of Swift GRBs have Av>1 mag ~5-15% have Av>2 mag?

28 Optical Extinction Bias? Dust-obscured star-formation is significant, and dusty galaxies should (in general) be: more massive more metal-rich more luminous redder than unobscured galaxies. OR, darkness could be entirely geometric (i.e., does the GRB sightline happen to pierce a molecular cloud or dust lane)

29 Goal How do dark hosts compare with other hosts and other galaxies, and what are the implications? ~8-25% of Swift GRBs have Av>1 mag ~5-15% have Av>2 mag?

30 Dark Burst Host Survey

31 Dark Burst Host Survey

32 Optically Ordinary-Looking... z<4 z = 1.35 ± 0.25 Xra y z = 2.1 z<4

33 Often Infrared Bright NIR (K-band) Optical (I-band) NIR (K-band) Optical (I-band) NIR (K-band) I K < 3.0 * Optical (I-band)

34 Dark Burst Host Colors (Le Floc'h et al. 2004)

35 Dark Burst Host Colors

36 Dark Burst Host Colors

37 Dark Burst Host Survey

38 Swift Dark GRB 4.5 μm Imaging

39 Pre-Swift Non-Dark GRBs

40 Swift Dark GRB 4.5 μm Imaging

41 Dark Burst Host Colors

42 Dark GRB I-band K-band Spitzer 4.5μm Fairly dark burst with... Extremely red host: I-K ~ 5.5 mag In top ~5% of brightest hosts observed by Spitzer, also detected at 24μm with MIPS Photo-z = (Svensson et al. 2011)

43 Red Dark Burst Host Galaxies? without dust with d u st?

44 Red Dark Burst Host Galaxies? Mass: Mo Luminosity: > Lo (>LIRG) Extinction: 1 3 mag?

45 Dark Burst Host Colors

46 Dark GRB A V+I-band H+K-band Spitzer 4.5μm Ultra-dark burst (Av > 5 mag), but Extremely blue host: I-K ~ 2 mag marginal or no Spitzer detection Ly-α emitter at z=2.1

47 Dark Burst Host Survey

48 Highly-Embedded Star Formation? Arp 220 SFR >> dust-corrected optical SFR Low-z: ULIRGs 100% ~20% of cosmic SFR at z~2 Michalowski et al. 2010, also Chapman et al % Gs ( Contribution to total SFR HST/NICMOS, Thomson & Scoville 1997 LIR High-z: SMGs Embedded ( hi-τ) SFR L o <L IR Normal galaxies (LI R < 1011 Lo) < ULIRGs (> 1012 Lo) L o) Typical Swift GRB redshift range 0 1 2

49 Pre-Swift Submillimeter Observations Relative fraction Only a few pre-swift detections (blue galaxies!) 9 9% ob a ur c s t ion fr ti o ac 9 n 0% o cu s b t io a r n 5 Tanvir et al o cti a fr 0% o n cu bs ULIRGs r io at n o cti a fr n Berger et al. 2003

50 Radio/submm observations No EVLA detection (to ~15 5 GHz) for 9 out of 10 Spitzer-brightest hosts 1 hr integration/target Of 20 hr/target 1(equiv. hr of EVLA on old VLA) exception: 40 ujy No CSO detection (to ~10 mjy) for 3 Spitzer-bright hosts 5-15 hr integration/target

51 LIRGs, not ULIRGs Lbol < 7 x 1011 Lbol < 2 x 1012 Lbol = (3 ± 2) x 1012 Lbol < 3 x 1012

52 LIRGs, not ULIRGs Mass: Mo L < 7 x 10 L < 2 x Luminosity: 10 3x1012 Lo (LIRG) Extinction: 1 3 mag Obscuration fraction: <~75%! b ol 11 Lbol = (3 ± 2) x 1012 bo l 12 Lbol < 3 x 1012

53 (Obscuration of all stars) host Fobs Obscuration Correlations host Av (Obscuration of observed stars)

54 optically thin (Obscuration of all stars) host Fobs optically thick Obscuration Correlations blue red host Av (Obscuration of observed stars)

55 SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs optically thick Obscuration Correlations blue red host Av (Obscuration of observed stars)

56 SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs afterglow Av (Obscuration of GRB) optically thick Obscuration Correlations blue red host Av (Obscuration of observed stars)

57 SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs afterglow Av (Obscuration of GRB) optically thick Obscuration Correlations blue red host Av (Obscuration of observed stars)

58 SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs afterglow Av (Obscuration of GRB) optically thick Obscuration Correlations blue red host Av (Obscuration of observed stars)

59 Obscuration Correlations SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs afterglow Av (Obscuration of GRB) optically thick 1. Red hosts produce red GRBs, not blue GRBs. blue red host Av (Obscuration of observed stars)

60 Obscuration Correlations SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs afterglow Av (Obscuration of GRB) optically thick 2. Blue hosts produce red GRBs and blue GRBs. blue red host Av (Obscuration of observed stars)

61 Obscuration Correlations SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs afterglow Av (Obscuration of GRB) optically thick 3. Red SMGs do not produce many GRBs. blue red host Av (Obscuration of observed stars)

62 Obscuration Correlations SMGs/ULIRGs blue SMGs LIRGs LBGs optically thin (Obscuration of all stars) host Fobs afterglow Av (Obscuration of GRB) optically thick 4. Blue SMGs do produce GRBs (but not red GRBs?) blue red host Av (Obscuration of observed stars)

63 Conclusions 1. Red hosts produce red GRBs, not blue GRBs. Dust in massive galaxies is globally distributed. Moderately metal-rich systems produce a few GRBs. 2. Blue hosts produce red GRBs and blue GRBs. Dust in low-mass galaxies is present, but heterogeneous: Some sightlines are dusty, others dust-free (geometry) 3. Red SMGs do not produce many GRBs. Chemically homogeneous, very metal-rich systems: GRB production is stifled? (Or, super-young progenitor...) 4. Blue SMGs do produce GRBs (but not red GRBs?) Chemically heterogeneous systems: GRB production can still occur in blue, outer parts

64 Conclusions 1. Red hosts produce red GRBs, not blue GRBs. Dust in massive galaxies is globally distributed. Moderately metal-rich systems produce a few GRBs. 2. Blue hosts produce red GRBs and blue GRBs. Dust in low-mass galaxies is present, but heterogeneous: Some sightlines are dusty, others dust-free (geometry) 3. Red SMGs do not produce many GRBs. Chemically homogeneous, very metal-rich systems: GRB production is stifled? (Or, super-young progenitor...) 4. Blue SMGs do produce GRBs (but not red GRBs?) Chemically heterogeneous systems: GRB production can still occur in blue, outer parts

65 Conclusions 1. Red hosts produce red GRBs, not blue GRBs. Dust in massive galaxies is globally distributed. Moderately metal-rich systems produce a few GRBs. 2. Blue hosts produce red GRBs and blue GRBs. Dust in low-mass galaxies is present, but heterogeneous: Some sightlines are dusty, others dust-free (geometry) 3. Red SMGs do not produce many GRBs. Chemically homogeneous, very metal-rich systems: GRB production is stifled? (Or, super-young progenitor...) 4. Blue SMGs do produce GRBs (but not red GRBs?) Chemically heterogeneous systems: GRB production can still occur in blue, outer parts

66 Conclusions 1. Red hosts produce red GRBs, not blue GRBs. Dust in massive galaxies is globally distributed. Moderately metal-rich systems produce a few GRBs. 2. Blue hosts produce red GRBs and blue GRBs. Dust in low-mass galaxies is present, but heterogeneous: Some sightlines are dusty, others dust-free (geometry) 3. Red SMGs do not produce many GRBs. Chemically homogeneous, very metal-rich systems: GRB production is stifled? (Or, super-young progenitor...) 4. Blue SMGs do produce GRBs (but not red GRBs?) Chemically heterogeneous systems: GRB production can still occur in blue, outer parts

67 Conclusions 1. Red hosts produce red GRBs, not blue GRBs. Dust in massive galaxies is globally distributed. Moderately metal-rich systems produce a few GRBs. 2. Blue hosts produce red GRBs and blue GRBs. Dust in low-mass galaxies is present, but heterogeneous: Some sightlines are dusty, others dust-free (geometry) 3. Red SMGs do not produce many GRBs. Chemically homogeneous, very metal-rich systems: GRB production is stifled? (Or, super-young progenitor...) 4. Blue SMGs do produce GRBs (but not red GRBs?) Chemically heterogeneous systems: GRB production can still occur in blue, outer parts

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