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Li, ML, Ho, AYQ, Ryan, G, Perley, DA, Lamb, GP, A.J., N, Andreoni, I, Anupama, GC, Bellm, EC, Berger, E, Bloom, JS, Burns, E, Caiazzo, I, Chandra, P, Coughlin, MW, El-Badry, K, Graham, MJ, Kasliwal, M, Keating, GK, Kulkarni, SR et al (2025) The Nature of Optical Afterglows without Gamma-Ray Bursts: Identification of AT2023lcr and Multiwavelength Modeling. The Astrophysical Journal, 985 (1). pp. 1-32. ISSN 0004-637X
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The Nature of Optical Afterglows without Gamma Ray Bursts Identification of AT2023lcr and Multiwavelength Modeling.pdf - Published Version Available under License Creative Commons Attribution. Download (177MB) | Preview |
Abstract
In the past few years, the improved sensitivity and cadence of wide-field optical surveys have enabled the discovery of several afterglows without associated detected gamma-ray bursts (GRBs). We present the identification, observations, and multiwavelength modeling of a recent such afterglow (AT2023lcr), and model three literature events (AT2020blt, AT2021any, and AT2021lfa) in a consistent fashion. For each event, we consider the following possibilities as to why a GRBwas not observed: (1) the jet was off-axis; (2) the jet had a low initial Lorentz factor; and (3) the afterglow was the result of an on-axis classical GRB (on-axis jet with physical parameters typical of the GRB population), but the emission was undetected by gamma-ray satellites. We estimate all physical parameters using afterglowpy and Markov Chain Monte Carlo methods from emcee. We find that AT2023lcr, AT2020blt, and AT2021any are consistent with on-axis classical GRBs, and AT2021lfa is consistent with both on-axis low Lorentz factor (Γ0 ≈ 5–13) and off-axis (θobs = 2θjet) high Lorentz factor (Γ0 ≈ 100) jets.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society |
| Date of acceptance: | 31 March 2025 |
| Date of first compliant Open Access: | 20 May 2025 |
| Date Deposited: | 20 May 2025 15:36 |
| Last Modified: | 20 May 2025 15:45 |
| DOI or ID number: | 10.3847/1538-4357/adc800 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/26388 |
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