The Host Galaxies of
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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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Edo berger harvard university

The Host Galaxies of

High-Redshift GRBs

Edo Berger

Harvard University


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


Edo berger harvard university

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


Edo berger harvard university

GRB Absorption Spectroscopy

QSOs act as background sources of illumination; GRBs are embedded within their host galaxies

40 kpc


Edo berger harvard university

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


Edo berger harvard university

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


Edo berger harvard university

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


Edo berger harvard university

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


Edo berger harvard university

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


Edo berger harvard university

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


Edo berger harvard university

GRB-DLA Counterparts

GRB 050904:

z = 6.295

L < L*

SFR < 6 M⊙/yr

M < 109 M⊙

Berger et al. 2007


Edo berger harvard university

GRB-DLA Counterparts

Spitzer/IRAC: z ~ 2 - 3

Spitzer/IRAC:

z ~ 3 - 5

Chary, Berger, & Cowie 2007

Laskar, Berger, & Chary 2010


Edo berger harvard university

GRB-DLA Counterparts

GOODS

z~1 GRBs

Chary, Berger, & Cowie 2007


Edo berger harvard university

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


Edo berger harvard university

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


Edo berger harvard university

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


Edo berger harvard university

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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