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Paterson, K, Fong, W, Nugent, A, Escorial, AR, Leja, J, Laskar, T, Chornock, R, Miller, AA, Scharwächter, J, Cenko, SB, Perley, DA, Tanvir, NR, Levan, A, Cucchiara, A, Cobb, BE, De, K, Berger, E, Terreran, G, Alexander, KD, Nicholl, M , Blanchard, PK and Cornish, D (2020) Discovery of the Optical Afterglow and Host Galaxy of Short GRB 181123B at z = 1.754: Implications for Delay Time Distributions. Astrophysical Journal, 898 (2). ISSN 0004-637X
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Discovery of the Optical Afterglow and Host Galaxy of Short GRB 181123B at z = 1.754 Implications for Delay Time Distributions.pdf - Accepted Version Download (12MB) | Preview |
Abstract
We present the discovery of the optical afterglow and host galaxy of the Swift short-duration gamma-ray burst (SGRB) GRB 181123B. Observations with Gemini-North starting ≈9.1 hr after the burst reveal a faint optical afterglow with i ≈ 25.1 mag at an angular offset of 0farcs59 ± 0farcs16 from its host galaxy. Using grizYJHK observations, we measure a photometric redshift of the host galaxy of $z={1.77}_{-0.17}^{+0.30}$. From a combination of Gemini and Keck spectroscopy of the host galaxy spanning 4500–18000 Å, we detect a single emission line at 13390 Å, inferred as Hβ at z = 1.754 ± 0.001 and corroborating the photometric redshift. The host galaxy properties of GRB 181123B are typical of those of other SGRB hosts, with an inferred stellar mass of ≈9.1 × 109 M ⊙, a mass-weighted age of ≈0.9 Gyr, and an optical luminosity of ≈0.9L*. At z = 1.754, GRB 181123B is the most distant secure SGRB with an optical afterglow detection and one of only three at z > 1.5. Motivated by a growing number of high-z SGRBs, we explore the effects of a missing z > 1.5 SGRB population among the current Swift sample on delay time distribution (DTD) models. We find that lognormal models with mean delay times of ≈4–6 Gyr are consistent with the observed distribution but can be ruled out to 95% confidence, with an additional ≈one to five Swift SGRBs recovered at z > 1.5. In contrast, power-law models with ∝t −1 are consistent with the redshift distribution and can accommodate up to ≈30 SGRBs at these redshifts. Under this model, we predict that ≈1/3 of the current Swift population of SGRBs is at z > 1. The future discovery or recovery of existing high-z SGRBs will provide significant discriminating power on their DTDs and thus their formation channels.
| Item Type: | Article |
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| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society; IOP Publishing |
| Date Deposited: | 06 Aug 2020 08:40 |
| Last Modified: | 04 Sep 2021 06:51 |
| DOI or ID number: | 10.3847/2041-8213/aba4b0 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/13452 |
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