The Redshift Distribution of Swift GRBs

  This webpage is intended to update the Swift GRB sample, first presented in an A&A paper and updated in this proceedings paper. In order to study the redshift distribution of GRBs, it is important to carefully select a sample containing bursts which have observing conditions favorable for redshift determination. We have used 6 criteria to construct such a sample (in this way, we pick those GRBs easier to observe, without altering the statistical distribution of the OAs for the GRBs in the sample):

  1. Small error circles, hence the bursts have to be localised with the XRT.
  2. The XRT error circle should be distributed quickly (within 12 hours) for a relatively rapid follow-up. Although the automatic slewing of Swift was enabled in the middle of January 2005, part of the following month was dedicated to calibration which could not be interrupted. Therefore, we have only included bursts occurring after 1 March 2005.
  3. The Galactic extinction in the direction to the burst has to be sufficiently small or AV < 0.5.
  4. Rejection of bursts with a declination unsuitable (above +70o or below -70o) for follow-up observations.
  5. The Sun-to-field distance has to be large enough, with θSun > 55o.
  6. No nearby bright star (excludes GRBs 051016A, 070721A, 071028A, 080229 and 090929B).

This sample (260 GRBs) is listed below the figures. The upper figure displays the cumulative fraction of GRBs as a function of redshift for 44 pre-Swift bursts (blue stepwise curve) and 136 Swift bursts (red stepwise curve). Overplotted is a model of the expected redshift distribution for Swift observable long GRBs using a SFR history which remains constant beyond z = 3 (see Jakobsson et al. 2012, in press, for details). Roughly 3% (8/260) of all GRBs are at z > 5. The lower figure is a simple histogram with some additional information (credit: Annalisa De Cia).

Note that in the table below, the redshift upper limits are based on the bluest filter the afterglow/host are detected in, and on Ly-alpha or the Ly-limit. Since some flux could be present between Ly-alpha and the Ly-limit for redshifts below around 5, we base the redshift upper limits on the Ly-limit for the bluest filters, including the V-band. For R-band and redder we use Ly-alpha.

For the bursts with non-detection of an OA we have examined the Swift/XRT GRB spectrum repository and looked the excess absorbing column (NH). Using the method of Grupe et al. (2007, AJ, 133, 2216) we have put a conservative redshift upper limits of z < 3.5 when NH > 2 x 1021 cm-2, and taking into account the 90% confidence errors on NH.






Update (4 November 2011):

GRB z AV θSun θMoon IMoon       Reference
111022B < 6.4 0.25 103 55 24       Moskvitin et al. (GCN#12491)
111016A < 6.4 0.13 59 72 81       Cenko et al. (GCN#12444)
111008A 4.99 0.02 121 87 90       Wiersema et al. (GCN#12431)
110928A < 3.5 (XRT) 0.10 78 78 1
110921A 0.46 110 120 40
110915A 0.19 138 73 91
110818A 3.36 0.12 129 90 77       D'Avanzo et al. (GCN#12284)
110808A 1.35 0.03 95 113 69       de Ugarte Postigo et al. (GCN#12258)
110726A < 2.7 0.26 103 93 23       Cucchiara et al. (GCN#12202)
110719A 0.13 81 54 84
110709B 0.16 71 48 69
110709A < 3.5 (XRT) 0.05 102 62 66
110530A < 2.7 0.19 92 85 5       De Cia et al. (GCN#12054)
110521A 0.29 56 152 80
110520A < 6.1 0.08 66 138 86       Xu et al. (GCN#12037)
110503A 1.61 0.08 79 73 0       de Ugarte Postigo et al. (GCN#11993)
110411A < 3.5 (XRT) 0.33 82 93 54
110407A < 5.5 0.09 155 115 15       Kann et al. (GCN#11906)
110402A < 2.0 0.06 114 113 3       Swenson et al. (GCN#11871)
110319A < 3.3 0.09 65 114 99       Siegel et al. (GCN#11812)
110312A < 3.5 (XRT) 0.13 162 70 58
110208A < 6.1 0.08 58 35 28       Berger et al. (GCN#11681)
110205A 2.22 0.05 126 116 4       Vreeswijk et al. (GCN#11640)
110128A 2.34 0.03 121 63 33       Sparre et al. (GCN#11607)
110106B 0.62 0.08 147 146 6       Chornock et al. (GCN#11538)
101219B 0.55 0.06 88 77 97       Sparre et al. (arXiv:1105.0422)
101024A < 6.1 0.29 88 99 98       Kruehler et al. (GCN#11383)
101023A < 5.5 0.11 87 103 99       Nardini et al. (GCN#11369)
101011A 0.10 103 89 20
100905A 0.19 128 88 12
100901A 1.41 0.32 125 34 52       Chornock et al. (GCN#11164)
100823A 0.12 129 61 99
100814A 1.44 0.07 124 149 22       O'Meara et al. (GCN#11089)
100802A 0.40 100 37 59
100728B < 3.3 0.22 84 73 95       Oates & Morris (GCN#11026)
100725A 0.16 62 108 100
100724A 1.29 0.14 77 81 96       Thöne et al. (GCN#10971)
100621A 0.54 0.10 135 94 71       Milvang-Jensen et al. (GCN#10876)
100615A 0.15 101 68 9
100614A 0.10 107 104 8
100606A 0.09 108 75 33
100526B 0.04 83 105 99
100526A < 15.0 0.14 132 47 99       Perley (GCN#10806)
100514A < 6.1 0.33 75 79 10       Rumyantsev & Pozanenko (GCN#10767)
100513A 4.77 0.18 117 129 1       Cenko et al. (GCN#10752)
100425A 1.76 0.50 99 126 85       Goldoni et al. (GCN#10684)
100424A < 11.0 0.11 165 45 82       Cenko et al. (GCN#10690)
100420A < 20.0 0.37 82 99 33       Levan et al. (GCN#10706)
100418A 0.62 0.24 126 142 20       Cucchiara & Fox (GCN#10624)
100413A < 3.5 (XRT) 0.37 112 101 1
100316D 0.06 0.39 100 104 0       Vergani et al. (GCN#10512)
100316C 0.12 71 77 0
100316B 1.18 0.47 131 137 0       Vergani et al. (GCN#10495)
100305A < 6.1 0.05 144 82 73       Cucchiara et al. (GCN#10473)
100219A 4.67 0.25 156 126 28       Groot et al. (GCN#10441)
100213B 0.60 0.26 144 143 0       Cucchiara et al. (GCN#10422)
100205A < 11.0 0.06 164 85 58       Tanvir et al. (GCN#10366)
100111A < 2.8 0.17 58 41 15       Hoversten et al. (GCN#10323)
091208B 1.06 0.18 137 126 60       Wiersema et al. (GCN#10263)
091130B 0.04 70 121 100
091127 0.49 0.13 132 40 80       Cucchiara et al. (GCN#10202)
091109A 3.08 0.10 75 152 60       Rau et al. (GCN#10350)
091104 0.05 64 103 100
091029 2.75 0.05 107 81 80       Chornock et al. (GCN#10100)
091020 1.71 0.06 67 93 10       Xu et al. (GCN#10053)
091018 0.97 0.10 112 105 0       Chen et al. (GCN#10038)
090926B 1.24 0.08 124 97 60       Fynbo et al. (GCN#9947)
090912 < 3.5 (XRT) 0.05 59 72 40
090904A < 6.1 0.33 67 117 100       Malesani et al. (GCN#10000)
090814A 0.70 0.26 89 130 50       Jakobsson et al. (GCN#9797)
090812 2.45 0.08 149 43 70       de Ugarte Postigo et al. (GCN#9771)
090809 2.74 0.32 162 29 90       Malesani et al. (GCN#9761)
090728 < 6.4 0.24 84 156 50       Melandri et al. (GCN#9726)
090715B 3.00 0.05 103 106 50       Wiersema et al. (GCN#9673)
090709A < 6.1 0.30 97 80 100       Cenko et al. (GCN#9646)
090607 0.05 91 88 100
090530 1.3 (photo-z) 0.08 99 34 40       Kruehler et al. (2011, A&A, 526, 153)
090529 2.63 0.07 123 68 30       Malesani et al. (GCN#9457)
090519 3.85 0.13 86 145 30       Levan et al. (GCN#9409)
090518 < 3.5 (XRT) 0.13 66 143 40
090516A 4.11 0.17 89 153 60       de Ugarte Postigo et al. (GCN#9383)
090429B 9.4 (photo-z) 0.05 133 96 20       Cucchiara et al. (arXiv:1105.4915)
090429A 0.18 76 94 90
090424 0.54 0.08 143 145 0       Chornock et al. (GCN#9243)
090423 8.3 0.10 111 134 0       Tanvir et al. (2009, Nature, 461, 1254)
090418A 1.61 0.15 106 65 40       Chornock et al. (GCN#9151)
090417B 0.35 0.06 122 106 50       Berger & Fox (GCN#9156)
090407 < 3.5 (XRT) 0.22 56 101 90
090404 < 3.5 (XRT) 0.07 121 92 70
090313 3.38 0.09 155 21 90       Chornock et al. (GCN#8994)
090308A 0.39 125 75 90
090205 4.65 0.39 90 140 80       Fugazza et al. (GCN#8892)
090201 < 3.5 (XRT) 0.22 105 87 40
090123 < 2.0 0.05 57 84 10       Marshall et al. (GCN#8846)
090113 0.28 107 108 90
090102 1.55 0.15 156 136 30       de Ugarte Postigo et al. (GCN#8766)
081230 2.0 (photo-z) 0.05 102 74 10       Kruehler et al. (2011, A&A, 526, 153)
081222 2.77 0.07 94 128 20       Cucchiara et al. (GCN#8713)
081221 < 3.5 (XRT) 0.07 93 140 30
081211A 0.10 61 105 100
081210 < 3.3 0.26 145 40 90       Krimm et al. (GCN#8648)
081203A 2.1 (first UVOT grism z!) 0.07 87 102 30       Kuin et al. (2009, MNRAS. 395, L21)
081128 0.15 139 132 0
081127 0.30 91 97 0
081121 2.51 0.17 95 86 30       Berger & Rauch (GCN#8542)
081118 2.58 0.15 112 77 60       D'Elia et al. (GCN#8531)
081109 < 5.0 0.06 85 59 80       Clemens et al. (GCN#8515)
081104 < 3.5 (XRT) 0.36 93 101 30
081029 3.85 0.10 92 87 0       D'Elia et al. (GCN#8438)
081028A 3.04 0.12 91 80 0       Berger et al. (GCN#8434)
081016B 0.03 127 73 90
081012 0.07 152 43 90
081008 1.97 0.31 82 41 60       Cucchiara et al. (GCN#8346)
081007 0.53 0.05 125 48 50       Berger et al. (GCN#8335)
080928 1.69 0.22 88 83 0       Vreeswijk et al. (GCN#8301)
080916B 0.07 67 101 100
080916A 0.69 0.06 124 68 100       Fynbo et al. (GCN#8254)
080913 6.70 0.14 106 92 100       Greiner et al. (2009, ApJ, 693, 1610)
080905B 2.37 0.16 116 116 61       Vreeswijk et al. (GCN#8191)
080810 3.35 0.09 141 110 70       Prochaska et al. (GCN#8083)
080805 1.51 0.14 134 104 20       Jakobsson et al. (GCN#8077)
080804 2.20 0.05 142 119 20       Thöne et al. (GCN#8058)
080727A 0.25 88 159 30
080721 2.59 0.34 106 110 90       Jakobsson et al. (GCN#7998)
080710 0.85 0.25 93 169 50       Perley et al. (GCN#7962)
080707 1.23 0.33 65 119 20       Fynbo et al. (GCN#7949)
080703 < 5.5 0.24 86 88 0       Ward & Ziaeepour (GCN#7941)
080613B 0.12 94 28 80
080607 3.04 0.07 109 64 20       Prochaska et al. (2009, ApJ, 691, L27)
080605 1.64 0.44 152 147 0       Jakobsson et al. (GCN#7832)
080604 1.42 0.16 134 127 0       Wiersema et al. (GCN#7818)
080603B 2.69 0.04 74 70 0       Fynbo et al. (GCN#7797)
080602 0.09 59 39 0
080523 < 3.0 0.08 90 69 90       Malesani et al. (GCN#7779)
080520 1.55 0.26 133 37 100       Jakobsson et al. (GCN#7757)
080430 0.77 0.04 99 136 30       Cucchiara & Fox (GCN#7654)
080413B 1.10 0.12 62 160 60       Vreeswijk et al. (GCN#7601)
080330 1.51 0.05 141 123 50       Malesani et al. (GCN#7544)
080325 1.9 (photo-z) 0.22 86 80 90       Hashimoto et al. (2010, ApJ, 719, 378)
080320 < 6.4 0.05 123 53 100       Tanvir et al. (GCN#7488)
080319C 1.95 0.09 96 90 90       Wiersema et al. (GCN#7517)
080319B 0.94 0.04 129 64 90       Vreeswijk et al. (GCN#7444)
080319A < 4.2 0.05 130 57 90       Perley et al. (2009, AJ, 138, 1690)
080310 2.43 0.13 131 157 10       Vreeswijk et al. (GCN#7391)
080307 < 6.1 0.09 138 140 0       Xin et al. (GCN#7371)
080212 < 3.5 0.49 89 160 30       Kuepcue Yoldas et al. (GCN#7303)
080210 2.64 0.27 77 107 10       Jakobsson et al. (GCN#7286)
080207 < 3.5 (XRT) 0.08 115 123 0
080205 < 5.5 0.30 126 139 0       Oates & Markwardt (GCN#7253)
071122 1.14 0.16 76 90 90       Cucchiara et al. (GCN#7124)
071117 1.33 0.08 79 49 50       Jakobsson et al. (GCN#7117)
071112C 0.82 0.39 167 145 10       Jakobsson et al. (GCN#7076)
071031 2.69 0.04 104 117 70       Ledoux et al. (GCN#7023)
071025 < 6.1 0.24 143 28 100       Williams et al. (GCN#6995)
071021 < 5.6 0.22 135 42 70       Piranomonte et al. (GCN#6985)
071020 2.15 0.21 91 164 60       Jakobsson et al. (GCN#6952)
070808 < 3.5 (XRT) 0.08 129 77 20
070802 2.45 0.08 108 65 90       Elíasdóttir et al. (2009, ApJ, 697, 1725)
070721B 3.63 0.10 88 156 40       Fynbo et al. (2009, ApJS, 185, 526)
070621 < 3.5 (XRT) 0.16 131 143 40
070611 2.04 0.04 91 47 20       Fynbo et al. (2009, ApJS, 185, 526)
070521 0.55 0.09 129 101 20       Hattori et al. (GCN#6444)
070520B 0.12 60 33 20
070518 < 2.0 0.06 103 96 0       Cucchiara et al. (GCN#6419)
070506 2.31 0.13 55 86 90       Fynbo et al. (2009, ApJS, 185, 526)
070419B < 5.9 0.30 80 108 10       de Ugarte Postigo et al. (GCN#6321)
070419A 0.97 0.09 124 101 10       Cenko et al. (GCN#6322)
070412 0.08 128 134 40
070330 < 5.5 0.21 98 105 90       Kuin et al. (GCN#6238)
070328 0.13 66 83 70
070318 0.84 0.06 62 66 0       Fynbo et al. (2009, ApJS, 185, 526)
070306 1.50 0.09 161 49 90       Jaunsen et al. (2008, ApJ, 681, 453)
070224 < 6.1 0.19 149 113 60       Thoene et al. (GCN#6154)
070223 < 6.1 0.05 147 89 40       Rol et al. (GCN#6221)
070219 < 3.5 (XRT) 0.12 95 94 0
070208 1.17 0.05 119 76 70       Cucchiara et al. (GCN#6083)
070129 < 3.5 0.45 89 53 90       Fynbo et al. (2009, ApJS, 185, 526)
070110 2.35 0.05 60 123 60       Fynbo et al. (2009, ApJS, 185, 526)
070103 < 3.5 (XRT) 0.22 83 99 100
061222A 2.09 0.33 106 94 0       Perley et al. (2009, AJ, 138, 1690)
061121 1.31 0.15 85 91 0       Bloom et al. (GCN#5826)
061110B 3.43 0.13 100 142 70       Fynbo et al. (2009, ApJS, 185, 526)
061110A 0.76 0.30 109 134 70       Fynbo et al. (2009, ApJS, 185, 526)
061102 0.14 66 149 80
061021 0.35 0.19 59 53 0       Fynbo et al. (2009, ApJS, 185, 526)
061007 1.26 0.07 117 65 100       Fynbo et al. (2009, ApJS, 185, 526)
061004 0.16 89 101 90
061002 0.15 59 103 70
060929 0.16 80 59 40
060927 5.46 0.21 146 94 20       Ruiz-Velasco et al. (2007, ApJ, 669, 1)
060923C < 11.0 0.21 165 156 0       Fox (GCN#5607)
060923B 0.49 63 52 0
060923A < 2.8 0.20 75 69 0       Tanvir et al. (2008, MNRAS, 388, 1743)
060919 < 3.5 (XRT) 0.24 98 129 10
060912A 0.94 0.18 151 44 70       Levan et al. (2007, MNRAS, 378, 1439)
060908 1.88 0.10 135 37 100       Fynbo et al. (2009, ApJS, 185, 526)
060904A 0.06 74 87 80
060814 0.84 0.13 73 141 60       Thoene et al. (GCN#6663)
060807 < 3.4 0.09 102 70 100       Fynbo et al. (2009, ApJS, 185, 526)
060805A 0.08 82 52 80
060729 0.54 0.18 85 87 20       Fynbo et al. (2009, ApJS 185, 526)
060719 < 4.6 0.03 112 72 30       Fynbo et al. (2009, ApJS, 185, 526)
060714 2.71 0.26 115 113 80       Jakobsson et al. (2006, A&A, 460, L13)
060712 0.04 63 137 100
060708 1.92 (photo-z) 0.04 110 95 90       Oates et al. (2009 MNRAS, 395, 490)
060707 3.43 0.07 115 104 90       Jakobsson et al. (2006, A&A, 460, L13)
060614 0.13 0.07 127 32 90       Fynbo et al. (2006, Nature, 444, 1047)
060607A 3.08 0.10 112 121 80       Fox et al. (2008, A&A, 491, 189)
060605 3.77 0.17 112 137 70       Ferrero et al. (2009, A&A, 497, 729)
060604 < 2.8 0.14 99 162 60       Blustin & Page (GCN#5219)
060526 3.21 0.22 156 156 0       Jakobsson et al. (2006, A&A, 460, L13)
060522 5.11 0.18 94 32 30       Cenko et al. (GCN#5155)
060512 2.1 0.06 113 68 100       Fynbo et al. (2009, ApJS, 185, 526)
060502A 1.51 0.11 97 81 20       Cucchiara et al. (GCN#5052)
060428B < 5.5 0.05 102 98 0       De Pasquale & Campana (GCN#5035)
060427 0.17 78 79 0
060323 < 4.4 0.05 128 124 40       Marshall & Vetere (GCN#4917)
060319 1.15 0.07 121 87 90       D. Perley (private communication)
060306 < 3.5 (XRT) 0.12 55 35 40
060219 < 3.5 (XRT) 0.11 97 55 60
060218 0.03 0.47 83 150 80       Sollerman et al. (2006, A&A, 454, 503)
060210 3.91 0.31 100 47 90       Cucchiara et al. (2006, Il Nuovo Cimento B, 121, 1455)
060206 4.05 0.04 121 114 60       Fynbo et al. (2006, A&A, 451, L47)
060204B < 4.8 0.06 112 136 43       Fynbo et al. (GCN#4677)
060202 0.78 0.16 93 45 20       Butler (2007, ApJ, 656, 1001)
060124 2.30 0.44 121 132 30       Mirabal et al. (GCN#4591)
060115 3.53 0.44 121 72 99       Piranomonte et al. (GCN#4520)
060111A < 5.5 0.09 61 111 90       Blustin et al. (GCN#4482)
060108 < 3.2 0.05 146 96 69       Oates et al. (2006, MNRAS, 372, 327)
051117B 0.18 130 48 97
051016B 0.94 0.11 73 117 99       Soderberg et al. (GCN#4186)
051006 < 3.5 (XRT) 0.22 83 121 12
051001 0.05 142 156 4
050922C 2.20 0.34 138 93 80       Jakobsson et al. (2006, A&A, 460, L13)
050922B 0.12 171 57 80
050915A < 15.0 0.09 93 109 86       Bloom (GCN#3990)
050908 3.35 0.08 146 151 16       Fynbo et al. (2009, ApJS, 185, 526)
050904 6.30 0.21 143 145 0       Kawai et al. (2006, Nature, 440, 184)
050824 0.83 0.12 129 17 77       Sollerman et al. (2007, A&A, 466, 839)
050822 0.05 105 63 93
050820A 2.61 0.15 147 34 100       Prochaska et al. (2007, ApJS, 168, 231)
050819 0.40 132 59 99
050814 5.3 (photo-z) 0.09 99 74 60       Jakobsson et al. (2006, A&A, 447, 897)
050803 0.25 136 113 4
050802 1.71 0.07 79 102 9       Fynbo et al. (GCN#3749)
050801 1.38 (photo-z) 0.32 82 127 15       Oates et al. (2009, MNRAS, 395, 490)
050730 3.97 0.17 84 150 31       Starling et al. (2005, A&A, 442, L21)
050726 < 5.5 0.21 88 147 73       Poole et al. (GCN#3698)
050716 < 11.0 0.37 108 125 64       Rol et al. (2007, MNRAS, 374, 1078)
050714B < 3.5 (XRT) 0.18 67 25 44
050525A 0.61 0.32 121 57 98       Foley et al. (GCN#3483)
050505 4.28 0.07 90 130 13       Berger et al. (2006, ApJ, 642, 979)
050502B 5.2 (photo-z) 0.10 98 177 42       Afonso et al. (2011, A&A, 526, 154)
050416A 0.65 0.10 145 69 44       Soderberg et al. (2007, ApJ, 661, 982)
050412 0.07 159 121 11
050406 2.7 (photo-z) 0.07 59 58 10       Schady et al. (2006, ApJ, 643, 276)
050401 2.90 0.22 122 36 62       Watson et al. (2006, ApJ, 652, 1011)
050319 3.24 0.04 132 44 61       Jakobsson et al. (2006, A&A, 460, L13)
050318 1.44 0.06 64 83 52       Berger et al. (2005, ApJ, 634, 501)
050315 1.95 0.16 59 114 24       Berger et al. (2005, ApJ, 634, 501)