CaltechAUTHORS
Published August 1, 2020 | Version Published + Submitted
Journal Article Open

Discovery of the Optical Afterglow and Host Galaxy of Short GRB 181123B at z = 1.754: Implications for Delay Time Distributions

Creators

  • 1. ROR icon Northwestern University
  • 2. ROR icon Harvard-Smithsonian Center for Astrophysics
  • 3. ROR icon University of Bath
  • 4. ROR icon Ohio University
  • 5. ROR icon Adler Planetarium
  • 6. ROR icon Goddard Space Flight Center
  • 7. ROR icon University of Maryland, College Park
  • 8. ROR icon Liverpool John Moores University
  • 9. ROR icon University of Leicester
  • 10. ROR icon Radboud University Nijmegen
  • 11. ROR icon University of Warwick
  • 12. ROR icon College of Marin
  • 13. ROR icon University of the Virgin Islands
  • 14. ROR icon George Washington University
  • 15. ROR icon California Institute of Technology
  • 16. ROR icon University of Birmingham
  • 17. ROR icon University of Edinburgh

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 0."59 ± 0."16 from its host galaxy. Using grizYJHK observations, we measure a photometric redshift of the host galaxy of z = 1.77^(+0.30)_(−0.17). 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.

Additional Information

© 2020 The American Astronomical Society. Received 2020 May 25; revised 2020 July 7; accepted 2020 July 8; published 2020 July 28. We acknowledge Sarah Wellons, Allison Strom, and David Sand for helpful discussions that aided this work and Mansi Kasliwal for facilitating Keck observations. The Fong Group at Northwestern acknowledges support by the National Science Foundation under grant Nos. AST-1814782 and AST-1909358. This work was also supported in part by the National Aeronautics and Space Administration through grant HST-GO-15606.001-A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555, and Chandra Award No. DD7-18095X, issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. M.N. is supported by a Royal Astronomical Society Research Fellowship. A.J.L has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 725246, TEDE; PI: Levan). A.A.M. is funded by the Large Synoptic Survey Telescope Corporation, the Brinson Foundation, and the Moore Foundation in support of the LSSTC Data Science Fellowship Program; he also receives support as a CIERA Fellow from the CIERA Postdoctoral Fellowship Program (Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University). J.L. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1701487. K.D.A. acknowledges support provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51403.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Based on observations obtained at the international Gemini Observatory (PIs: Paterson, Fong; Program IDs GS-2018B-Q-112, GN-2018B-Q-117, GS-2019A-FT-107), a program of NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). W. M. Keck Observatory and MMT Observatory access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). Some of the data presented herein were obtained at the W. M. Keck Observatory (PIs: Miller, Fong, Paterson; Programs 2018B_NW254, 2018B_NW249, 2019A_O329), which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution (PI: Fong; Programs 2018C-UAO-G4, 2019A-UAO-G7, 2020A-UAO-G212-20A). This research was supported in part through the computational resources and staff contributions provided for the Quest high-performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. Facilities: Swift (XRT and UVOT) - Swift Gamma-Ray Burst Mission, Gemini-North (GMOS) - , Gemini-South (GMOS - , FLAMINGOS-2) - , Keck:I (MOSFIRE) - , Keck:II (DEIMOS) - , MMT (MMIRS). -

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Published - Paterson_2020_ApJL_898_L32.pdf

Submitted - 2007.03715.pdf

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Additional details

Identifiers

Eprint ID
104603
Resolver ID
CaltechAUTHORS:20200728-095149443

Related works

Describes
https://arxiv.org/abs/2007.03715 (URL)

Funding

NSF
AST-1814782
NSF
AST-1909358
NASA
HST-GO-15606.001-A
NASA
NAS5-26555
NASA Chandra
DD7-18095X
NASA
NAS8-03060
Royal Astronomical Society
European Research Council (ERC)
725246
Large Synoptic Survey Telescope Corporation
Brinson Foundation
Gordon and Betty Moore Foundation
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)
Northwestern University
NSF Astronomy and Astrophysics Fellowship
AST-1701487
NASA
HST-HF2-51403.001-A
W. M. Keck Foundation

Dates

Created
2020-07-28
Created from EPrint's datestamp field
Updated
2021-11-16
Created from EPrint's last_modified field