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Ho, AYQ, Perley, DA, Beniamini, P, Cenko, SB, Kulkarni, SR, Andreoni, I, Singer, LP, De, K, Kasliwal, MM, Fremling, C, Bellm, EC, Dekany, R, Delacroix, A, Duev, DA, Goldstein, DA, Golkhou, VZ, Goobar, A, Graham, MJ, Hale, D, Kupfer, T , Laher, RR, Masci, FJ, Miller, AA, Neill, JD, Riddle, R, Rusholme, B, Shupe, DL, Smith, R, Sollerman, J and van Roestel, J (2020) ZTF20aajnksq (AT 2020blt): A Fast Optical Transient at z 2.9 with No Detected Gamma-Ray Burst Counterpart. Astrophysical Journal, 905 (2). ISSN 0004-637X
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ZTF20aajnksq (AT 2020blt) A Fast Optical Transient at z 2.9 with No Detected Gamma-Ray Burst Counterpart.pdf - Accepted Version Download (1MB) | Preview |
Abstract
We present ZTF20aajnksq (AT 2020blt), a fast-fading (Δr = 2.3 mag in Δt = 1.3 days) red (g − r ≈ 0.6 mag) and luminous (M1626 Å = −25.9 mag) optical transient at z = 2.9 discovered by the Zwicky Transient Facility (ZTF). AT 2020blt shares several features in common with afterglows to long-duration gamma-ray bursts (GRBs): (1) an optical light curve well-described by a broken power law with a break at tj = 1 d (observer frame); (2) a luminous (L0.3–10 KeV = 1046 erg s−1) X-ray counterpart; and (3) luminous (L10 GHz = 4 × 1031 erg s−1 Hz−1) radio emission. However, no GRB was detected in the 0.74 days between the last ZTF nondetection (r > 21.36 mag) and the first ZTF detection (r = 19.60 mag), with an upper limit on the isotropic-equivalent gamma-ray energy release of Eγ,iso < 7 × 1052 erg. AT 2020blt is thus the third afterglow-like transient discovered without a detected GRB counterpart (after PTF11agg and ZTF19abvizsw) and the second (after ZTF19abvizsw) with a redshift measurement. We conclude that the properties of AT 2020blt are consistent with a classical (initial Lorentz factor Γ0 gsim 100) on-axis GRB that was missed by high-energy satellites. Furthermore, by estimating the rate of transients with light curves similar to that of AT 2020blt in ZTF high-cadence data, we agree with previous results that there is no evidence for an afterglow-like phenomenon that is significantly more common than classical GRBs, such as dirty fireballs. We conclude by discussing the status and future of fast-transient searches in wide-field high-cadence optical surveys.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, 0306 Physical Chemistry (incl. Structural) |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society; IOP Publishing |
| Related URLs: | |
| Date Deposited: | 30 Mar 2021 11:18 |
| Last Modified: | 17 Dec 2021 00:50 |
| DOI or ID number: | 10.3847/1538-4357/abc34d |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/14720 |
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