| Title: |
GRB 250704B: An Off-axis Short GRB with a Long-lived Afterglow Plateau |
| Authors: |
Swain, Vishwajeet; Ahumada, Tomás; Patil, Sameer K.; Wagh, Yogesh; Bhalerao, Varun; Nakar, Ehud; Kasliwal, Mansi; Hall, Xander J.; Busmann, Malte; Pathak, Utkarsh; Anand, Shreya; Karambelkar, Viraj; Andreoni, Igor; Anupama, G. C.; Arya, Anuraag; Balasubramanian, Arvind; Barway, Sudhanshu; Carney, Jonathan; Coughlin, Michael; Eappachen, D.; Freeburn, James; Gruen, Daniel; Mohan, Tanishk; O'Connor, Brendan; Palmese, Antonella; Sahu, D. K.; Saikia, Aditya Pawan; Sarin, Nikhil; Srinivasaragavan, Gokul; Tanenia, Hitesh |
| Source: |
Astrophysical Journal Letters, 996(2), L38, (2026-01-10) |
| Publisher Information: |
American Astronomical Society |
| Publication Year: |
2026 |
| Collection: |
Caltech Authors (California Institute of Technology) |
| Subject Terms: |
Gamma-ray astronomy; Astronomical methods; Gamma-ray sources; Optical astronomy |
| Description: |
We present a detailed multiwavelength afterglow study of the short gamma-ray burst (GRB) GRB 250704B, extensively monitored in optical and near-infrared bands. Its afterglow displays an unusually long duration plateau followed by an achromatic break and a steep decline, deviating from canonical GRB afterglows. While long plateaus are often explained by central engine activity, we find that for GRB 250704B an energy injection model requires unreasonable parameters. The afterglow is better explained by an off-axis power-law structured jet with a narrow core ( θ c ≈0:7) viewed at a modest angle ( θ v ≈ 1:9). A comparison with GRB 170817A shows that both events are consistent with the off-axis structured jet scenario, where the shape of the light curve is governed primarily by the geometry of the jet and the viewing angle rather than the energetics, microphysical parameters, or external density. Our results underscore the importance of incorporating the jet structure in GRB modeling. ; © 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence . Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. ; We thank the anonymous referee for the comments and suggestions that have helped us to improve the Letter. We thank all members of the GROWTH collaboration for helping with observations and data processing. GIT (H. Kumar et al. 2022 ) is a 70 cm telescope with a 07 field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (IAO; Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/ . This work is ... |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
https://arxiv.org/abs/arXiv:2509.02769; https://authors.library.caltech.edu/communities/caltechauthors/ |
| DOI: |
10.3847/2041-8213/ae2a20 |
| Availability: |
https://doi.org/10.3847/2041-8213/ae2a20 |
| Rights: |
info:eu-repo/semantics/openAccess ; Creative Commons Attribution 4.0 International ; https://creativecommons.org/licenses/by/4.0/legalcode |
| Accession Number: |
edsbas.B187B0B8 |
| Database: |
BASE |