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Edo Berger Harvard University

The Host Galaxies of High-Redshift GRBs. Edo Berger Harvard University. Outline. 1. GRBs at z<1: Is there a low-metallicity bias?. 2. The ISM of high-redshift galaxies. 3. DLA counterparts & the M-Z relation at z>2. Spitzer stack. Long GRBs Hosts: Metallicity?. metallicity.

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Edo Berger Harvard University

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  1. The Host Galaxies of High-Redshift GRBs Edo Berger Harvard University

  2. Outline 1.GRBs at z<1: Is there a low-metallicity bias? 2.The ISM of high-redshift galaxies 3.DLA counterparts & the M-Z relation at z>2 Spitzer stack

  3. Long GRBs Hosts: Metallicity? metallicity redshift mass Levesque, Berger, & Kewley 2009,2010 Low-Z “preference” at z<1; essentially disappears by z~2 Wainwright, EB & Penprase 2007, ApJ

  4. GRB Absorption Spectroscopy QSOs act as background sources of illumination; GRBs are embedded within their host galaxies 40 kpc

  5. GRB Absorption Spectroscopy QSOs act as background sources of illumination; GRBs are embedded within their host galaxies • GRBs vs. quasars: • Small impact parameter • No Mpc proximity effect • In star forming regions • High(er) redshift • Power law spectrum • Fade away 40 kpc

  6. GRB Absorption Spectroscopy Intrinsic Ly series absorption Lyα forest Metals log NH =22.1±0.1 [S/H] = 0.06 Z⦿ Berger et al. 2006

  7. GRB-DLAs 〈ZGRB〉~ 3 x〈ZQSO〉 MW GMCs Berger et al. 2006; Prochaska et al. 2007; Savaglio et al. 2007 Berger et al. 2006; Fynbo et al. 2009 〈N(HI)GRB〉~ 10 x〈N(HI)QSO〉 Complication for reionization? Avi’s question

  8. QSO-DLA Counterparts DLA? HST/NICMOS: H=22 mag; 1/22 detected HST/NICMOS: H=23 mag; confused QSO Colbert & Malkan 2002 Warren et al. 2001

  9. GRB-DLA Counterparts 1. GRBs have <1″ offset: No ambiguity about the identity of the DLA counterpart 2. GRBs fade away: Counterpart can be imaged to L≪ L* regardless of PSF

  10. GRB-DLA Counterparts HST/ACS 1″=1.75 kpc Vreeswijk et al. 2004 Wainwright, Berger, & Penprase 2007 z = 3.372 • F606W(AB) = 28.1 mag • L ≈ 0.02 L* • SFR ≈ 1 M⊙/yr

  11. GRB-DLA Counterparts GRB 050904: z = 6.295 L < L* SFR < 6 M⊙/yr M < 109 M⊙ Berger et al. 2007

  12. GRB-DLA Counterparts Spitzer/IRAC: z ~ 2 - 3 Spitzer/IRAC: z ~ 3 - 5 Chary, Berger, & Cowie 2007 Laskar, Berger, & Chary 2010

  13. GRB-DLA Counterparts GOODS z~1 GRBs Chary, Berger, & Cowie 2007

  14. The M-Z & L-Z Relations at z > 2 z ~ 4 z ~ 4 Chary, Berger, & Cowie 2007 z ~ 0: Tremonti et al. 2004 z ~ 1: Kobulnicky & Kewley 2004; Savaglio et al. 2005 z ~ 2: Erb et al. 2006

  15. The Host of GRB090423 @ z=8.2 Detection at 3.6 m 46 days after the burst (5 days in the rest-frame): 72 hr exposure: 27.2 AB mag = 48 nJy 2nd epoch in 2/2010 to detect the underlying host galaxy, and … No Detection: L < 0.1 L* Chary, Berger, et al. 2009

  16. Obscured Star Formation? z~1-2: SFR ~ 100−300 M⊙/yr LFIR ~ 1012 L⊙ ALMA/EVLA: detections to z~4-6; e.g. correlation of CO & Z

  17. Conclusions • GRBs are a powerful probe of the ISM of high-z galaxies, at redshifts that cannot be currently probed by direct spectroscopic observations • The environments probed by GRBs have higher neutral hydrogen and metal columns than those probed by quasars: probes of star forming regions • Host galaxy observations will soon provide the first M-Z and L-Z relations at z > 2, as well as a mass function of DLAs

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