Discovery of a cosmological, relativistic outburst via its rapidly fading optical emission

S. Bradley Cenko, S. R. Kulkarni, Assaf Horesh, Alessandra Corsi, Derek Brindley Fox, John Carpenter, Dale A. Frail, Peter E. Nugent, Daniel A. Perley, D. Gruber, Avishay Gal-Yam, Paul J. Groot, G. Hallinan, Eran O. Ofek, Arne Rau, Chelsea L. MacLeod, Adam A. Miller, Joshua S. Bloom, Alexei V. Filippenko, Mansi M. Kasliwal & 9 others Nicholas M. Law, Adam N. Morgan, David Polishook, Dovi Poznanski, Robert M. Quimby, Branimir Sesar, Ken J. Shen, Jeffrey M. Silverman, Assaf Sternberg

Research output: Contribution to journalArticle

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Abstract

We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g′-R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection of incoherent radio emission at such distances implies a large emitting region, from which we infer the presence of relativistic ejecta. The observed properties are all consistent with the population of long-duration gamma-ray bursts (GRBs), marking the first time such an outburst has been discovered in the distant universe independent of a high-energy trigger. We searched for possible high-energy counterparts to PTF11agg, but found no evidence for associated prompt emission. We therefore consider three possible scenarios to account for a GRB-like afterglow without a high-energy counterpart: an "untriggered" GRB (lack of satellite coverage), an "orphan" afterglow (viewing-angle effects), and a "dirty fireball" (suppressed high-energy emission). The observed optical and radio light curves appear inconsistent with even the most basic predictions for off-axis afterglow models. The simplest explanation, then, is that PTF11agg is a normal, on-axis long-duration GRB for which the associated high-energy emission was simply missed. However, we have calculated the likelihood of such a serendipitous discovery by PTF and find that it is quite small (≈2.6%). While not definitive, we nonetheless speculate that PTF11agg may represent a new, more common (>4 times the on-axis GRB rate at 90% confidence) class of relativistic outbursts lacking associated high-energy emission. If so, such sources will be uncovered in large numbers by future wide-field optical and radio transient surveys.

Original languageEnglish (US)
Article number130
JournalAstrophysical Journal
Volume769
Issue number2
DOIs
StatePublished - Jun 1 2013

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fading
outburst
light emission
gamma ray bursts
afterglows
radio
energy
industrial plants
flare stars
dwarf novae
orphan
fireballs
ejecta
radio emission
light curve
marking
confidence
universe
actuators
prediction

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Cenko, S. B., Kulkarni, S. R., Horesh, A., Corsi, A., Fox, D. B., Carpenter, J., ... Sternberg, A. (2013). Discovery of a cosmological, relativistic outburst via its rapidly fading optical emission. Astrophysical Journal, 769(2), [130]. https://doi.org/10.1088/0004-637X/769/2/130
Cenko, S. Bradley ; Kulkarni, S. R. ; Horesh, Assaf ; Corsi, Alessandra ; Fox, Derek Brindley ; Carpenter, John ; Frail, Dale A. ; Nugent, Peter E. ; Perley, Daniel A. ; Gruber, D. ; Gal-Yam, Avishay ; Groot, Paul J. ; Hallinan, G. ; Ofek, Eran O. ; Rau, Arne ; MacLeod, Chelsea L. ; Miller, Adam A. ; Bloom, Joshua S. ; Filippenko, Alexei V. ; Kasliwal, Mansi M. ; Law, Nicholas M. ; Morgan, Adam N. ; Polishook, David ; Poznanski, Dovi ; Quimby, Robert M. ; Sesar, Branimir ; Shen, Ken J. ; Silverman, Jeffrey M. ; Sternberg, Assaf. / Discovery of a cosmological, relativistic outburst via its rapidly fading optical emission. In: Astrophysical Journal. 2013 ; Vol. 769, No. 2.
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abstract = "We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g′-R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection of incoherent radio emission at such distances implies a large emitting region, from which we infer the presence of relativistic ejecta. The observed properties are all consistent with the population of long-duration gamma-ray bursts (GRBs), marking the first time such an outburst has been discovered in the distant universe independent of a high-energy trigger. We searched for possible high-energy counterparts to PTF11agg, but found no evidence for associated prompt emission. We therefore consider three possible scenarios to account for a GRB-like afterglow without a high-energy counterpart: an {"}untriggered{"} GRB (lack of satellite coverage), an {"}orphan{"} afterglow (viewing-angle effects), and a {"}dirty fireball{"} (suppressed high-energy emission). The observed optical and radio light curves appear inconsistent with even the most basic predictions for off-axis afterglow models. The simplest explanation, then, is that PTF11agg is a normal, on-axis long-duration GRB for which the associated high-energy emission was simply missed. However, we have calculated the likelihood of such a serendipitous discovery by PTF and find that it is quite small (≈2.6{\%}). While not definitive, we nonetheless speculate that PTF11agg may represent a new, more common (>4 times the on-axis GRB rate at 90{\%} confidence) class of relativistic outbursts lacking associated high-energy emission. If so, such sources will be uncovered in large numbers by future wide-field optical and radio transient surveys.",
author = "Cenko, {S. Bradley} and Kulkarni, {S. R.} and Assaf Horesh and Alessandra Corsi and Fox, {Derek Brindley} and John Carpenter and Frail, {Dale A.} and Nugent, {Peter E.} and Perley, {Daniel A.} and D. Gruber and Avishay Gal-Yam and Groot, {Paul J.} and G. Hallinan and Ofek, {Eran O.} and Arne Rau and MacLeod, {Chelsea L.} and Miller, {Adam A.} and Bloom, {Joshua S.} and Filippenko, {Alexei V.} and Kasliwal, {Mansi M.} and Law, {Nicholas M.} and Morgan, {Adam N.} and David Polishook and Dovi Poznanski and Quimby, {Robert M.} and Branimir Sesar and Shen, {Ken J.} and Silverman, {Jeffrey M.} and Assaf Sternberg",
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Cenko, SB, Kulkarni, SR, Horesh, A, Corsi, A, Fox, DB, Carpenter, J, Frail, DA, Nugent, PE, Perley, DA, Gruber, D, Gal-Yam, A, Groot, PJ, Hallinan, G, Ofek, EO, Rau, A, MacLeod, CL, Miller, AA, Bloom, JS, Filippenko, AV, Kasliwal, MM, Law, NM, Morgan, AN, Polishook, D, Poznanski, D, Quimby, RM, Sesar, B, Shen, KJ, Silverman, JM & Sternberg, A 2013, 'Discovery of a cosmological, relativistic outburst via its rapidly fading optical emission', Astrophysical Journal, vol. 769, no. 2, 130. https://doi.org/10.1088/0004-637X/769/2/130

Discovery of a cosmological, relativistic outburst via its rapidly fading optical emission. / Cenko, S. Bradley; Kulkarni, S. R.; Horesh, Assaf; Corsi, Alessandra; Fox, Derek Brindley; Carpenter, John; Frail, Dale A.; Nugent, Peter E.; Perley, Daniel A.; Gruber, D.; Gal-Yam, Avishay; Groot, Paul J.; Hallinan, G.; Ofek, Eran O.; Rau, Arne; MacLeod, Chelsea L.; Miller, Adam A.; Bloom, Joshua S.; Filippenko, Alexei V.; Kasliwal, Mansi M.; Law, Nicholas M.; Morgan, Adam N.; Polishook, David; Poznanski, Dovi; Quimby, Robert M.; Sesar, Branimir; Shen, Ken J.; Silverman, Jeffrey M.; Sternberg, Assaf.

In: Astrophysical Journal, Vol. 769, No. 2, 130, 01.06.2013.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Discovery of a cosmological, relativistic outburst via its rapidly fading optical emission

AU - Cenko, S. Bradley

AU - Kulkarni, S. R.

AU - Horesh, Assaf

AU - Corsi, Alessandra

AU - Fox, Derek Brindley

AU - Carpenter, John

AU - Frail, Dale A.

AU - Nugent, Peter E.

AU - Perley, Daniel A.

AU - Gruber, D.

AU - Gal-Yam, Avishay

AU - Groot, Paul J.

AU - Hallinan, G.

AU - Ofek, Eran O.

AU - Rau, Arne

AU - MacLeod, Chelsea L.

AU - Miller, Adam A.

AU - Bloom, Joshua S.

AU - Filippenko, Alexei V.

AU - Kasliwal, Mansi M.

AU - Law, Nicholas M.

AU - Morgan, Adam N.

AU - Polishook, David

AU - Poznanski, Dovi

AU - Quimby, Robert M.

AU - Sesar, Branimir

AU - Shen, Ken J.

AU - Silverman, Jeffrey M.

AU - Sternberg, Assaf

PY - 2013/6/1

Y1 - 2013/6/1

N2 - We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g′-R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection of incoherent radio emission at such distances implies a large emitting region, from which we infer the presence of relativistic ejecta. The observed properties are all consistent with the population of long-duration gamma-ray bursts (GRBs), marking the first time such an outburst has been discovered in the distant universe independent of a high-energy trigger. We searched for possible high-energy counterparts to PTF11agg, but found no evidence for associated prompt emission. We therefore consider three possible scenarios to account for a GRB-like afterglow without a high-energy counterpart: an "untriggered" GRB (lack of satellite coverage), an "orphan" afterglow (viewing-angle effects), and a "dirty fireball" (suppressed high-energy emission). The observed optical and radio light curves appear inconsistent with even the most basic predictions for off-axis afterglow models. The simplest explanation, then, is that PTF11agg is a normal, on-axis long-duration GRB for which the associated high-energy emission was simply missed. However, we have calculated the likelihood of such a serendipitous discovery by PTF and find that it is quite small (≈2.6%). While not definitive, we nonetheless speculate that PTF11agg may represent a new, more common (>4 times the on-axis GRB rate at 90% confidence) class of relativistic outbursts lacking associated high-energy emission. If so, such sources will be uncovered in large numbers by future wide-field optical and radio transient surveys.

AB - We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g′-R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection of incoherent radio emission at such distances implies a large emitting region, from which we infer the presence of relativistic ejecta. The observed properties are all consistent with the population of long-duration gamma-ray bursts (GRBs), marking the first time such an outburst has been discovered in the distant universe independent of a high-energy trigger. We searched for possible high-energy counterparts to PTF11agg, but found no evidence for associated prompt emission. We therefore consider three possible scenarios to account for a GRB-like afterglow without a high-energy counterpart: an "untriggered" GRB (lack of satellite coverage), an "orphan" afterglow (viewing-angle effects), and a "dirty fireball" (suppressed high-energy emission). The observed optical and radio light curves appear inconsistent with even the most basic predictions for off-axis afterglow models. The simplest explanation, then, is that PTF11agg is a normal, on-axis long-duration GRB for which the associated high-energy emission was simply missed. However, we have calculated the likelihood of such a serendipitous discovery by PTF and find that it is quite small (≈2.6%). While not definitive, we nonetheless speculate that PTF11agg may represent a new, more common (>4 times the on-axis GRB rate at 90% confidence) class of relativistic outbursts lacking associated high-energy emission. If so, such sources will be uncovered in large numbers by future wide-field optical and radio transient surveys.

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