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GRB 050814 at z = 5.3 and a Mean Redshift of 2.8 for Swift
GRBsA&A, in press (astro-ph/0509888)
Páll JakobssonRobert PriddeyDarach WatsonPriya Natarajan
Andrew LevanJens HjorthBrian L. JensenJavier Gorosabel
Johan P. U. FynboNial TanvirJesper SollermanKristian Pedersen
X2.7
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GRB 050814
t90 = 65+40-20 s (poorly constrained).
XRT source @ 138 s.UVOT @ 167 s: V > 20.5 mag.
NOT observations of OA @ 14 hours:V > 25.2 mag; R = 23.4 mag; I = 20.6 mag.
R – I 2.8 mag β 11.7
UKIRT detection in the NIR (J and K).
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Spectral Energy Distribution
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Spectral Energy Distribution
GRB 050814 (z = 5.3) GRB 050904 (z = 6.3)
Tagliaferri et al. (2005)
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Spectral Energy Distribution
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2(z) for GRB 050814
z = 5.3 ± 0.3
β = 1.0 (fixed)
AV 0.9 mag
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The Redshift Distribution of Swift LGRBs
Is it consistent with models were GRBs trace the global star formation?
Important to construct a “clean” sample as unbiased as possible.
Metallicity dependence?
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Selection Criteria
Small error circles: XRT localization (68).
Sufficiently small Galactic extinction:AV < 0.5 mag (46).
Quick distribution of XRT error circles for a relatively rapid follow-up: after 1 March 2005 (39).
Reject bursts with an unsuitable declination:above +70º or below –70º (36).
A total of 83 long-duration Swift GRBs
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The Sample (36 bursts)
050315 050318050319050401050406050412050416A050502B050505050525050603050714B
050716050726050730050801050802050803050814050819050820A050822050824050904
050908050915A050922B050922C051001051006051008051012051016A051016B051117A051117B
1.95 1.44 3.24 2.90< 3.5
0.65< 8.5 4.27 0.61 2.82
< 8.0 < 5.0 3.97< 2.0 1.71
5.3
2.61 0.83 6.29
3.34 < 13.0 2.20
0.94
GRB GRB GRBz z z
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Cumulative Fraction
Natarajan et al. (2005)Gorosabel et al. (2004)
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At least 6% @ z > 5
050315 050318050319050401050406050412050416A050502B050505050525050603050714B
050716050726050730050801050802050803050814050819050820A050822050824050904
050908050915A050922B050922C051001051006051008051012051016A051016B051117A051117B
1.95 1.44 3.24 2.90< 3.5
0.65< 8.5 4.27 0.61 2.82
< 8.0 < 5.0 3.97< 2.0 1.71
5.3
2.61 0.83 6.29
3.34 < 13.0 2.20
0.94
GRB GRB GRBz z z