GRB 250704B: An Off-axis Short GRB with a Long-lived Afterglow Plateau

Vishwajeet Swain; Tomás Ahumada; Sameer K. Patil; Yogesh Wagh; Varun Bhalerao; Ehud Nakar; Mansi Kasliwal; Xander J. Hall; Malte Busmann; Utkarsh Pathak; Shreya Anand; Viraj Karambelkar; Igor Andreoni; G. C. Anupama; Anuraag Arya; Arvind Balasubramanian; Sudhanshu Barway; Jonathan Carney; Michael Coughlin; D. Eappachen; James Freeburn; Daniel Gruen; Tanishk Mohan; Brendan O’Connor; Antonella Palmese; D. K. Sahu; Aditya Pawan Saikia; Nikhil Sarin; Gokul Srinivasaragavan; Hitesh Tanenia

doi:10.3847/2041-8213/ae2a20

GRB 250704B: An Off-axis Short GRB with a Long-lived Afterglow Plateau

Vishwajeet Swain
, Tomás Ahumada
, Sameer K. Patil
, Yogesh Wagh
, Varun Bhalerao
, Ehud Nakar
, Mansi Kasliwal
, Xander J. Hall
, Malte Busmann
, Utkarsh Pathak
, Shreya Anand
, Viraj Karambelkar
, Igor Andreoni
, G. C. Anupama
, Anuraag Arya
, Arvind Balasubramanian
, Sudhanshu Barway
, Jonathan Carney
, Michael Coughlin
, D. Eappachen

James Freeburn, Daniel Gruen, Tanishk Mohan, Brendan O’Connor, Antonella Palmese, D. K. Sahu, Aditya Pawan Saikia, Nikhil Sarin, Gokul Srinivasaragavan, Hitesh Tanenia

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

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.

Original language	English (US)
Article number	L38
Journal	Astrophysical Journal Letters
Volume	996
Issue number	2
DOIs	https://doi.org/10.3847/2041-8213/ae2a20
State	Published - Jan 10 2026
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2026. The Author(s). Published by the American Astronomical Society.

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10.3847/2041-8213/ae2a20

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Swain, V., Ahumada, T., Patil, S. K., Wagh, Y., Bhalerao, V., Nakar, E., Kasliwal, M., Hall, X. J., Busmann, M., Pathak, U., Anand, S., Karambelkar, V., Andreoni, I., Anupama, G. C., Arya, A., Balasubramanian, A., Barway, S., Carney, J., Coughlin, M., ... Tanenia, H. (2026). GRB 250704B: An Off-axis Short GRB with a Long-lived Afterglow Plateau. Astrophysical Journal Letters, 996(2), Article L38. https://doi.org/10.3847/2041-8213/ae2a20

Swain, V, Ahumada, T, Patil, SK, Wagh, Y, Bhalerao, V, Nakar, E, Kasliwal, M, Hall, XJ, Busmann, M, Pathak, U, Anand, S, Karambelkar, V, Andreoni, I, Anupama, GC, Arya, A, Balasubramanian, A, Barway, S, Carney, J, Coughlin, M, Eappachen, D, Freeburn, J, Gruen, D, Mohan, T, O’Connor, B, Palmese, A, Sahu, DK, Saikia, AP, Sarin, N, Srinivasaragavan, G & Tanenia, H 2026, 'GRB 250704B: An Off-axis Short GRB with a Long-lived Afterglow Plateau', Astrophysical Journal Letters, vol. 996, no. 2, L38. https://doi.org/10.3847/2041-8213/ae2a20

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title = "GRB 250704B: An Off-axis Short GRB with a Long-lived Afterglow Plateau",

abstract = "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 (θc ≈ 0. °7) viewed at a modest angle (θv ≈ 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.",

author = "Vishwajeet Swain and Tom{\'a}s Ahumada and Patil, \{Sameer K.\} and Yogesh Wagh and Varun Bhalerao and Ehud Nakar and Mansi Kasliwal and Hall, \{Xander J.\} and Malte Busmann and Utkarsh Pathak and Shreya Anand and Viraj Karambelkar and Igor Andreoni and Anupama, \{G. C.\} and Anuraag Arya and Arvind Balasubramanian and Sudhanshu Barway and Jonathan Carney and Michael Coughlin and D. Eappachen and James Freeburn and Daniel Gruen and Tanishk Mohan and Brendan O{\textquoteright}Connor and Antonella Palmese and Sahu, \{D. K.\} and Saikia, \{Aditya Pawan\} and Nikhil Sarin and Gokul Srinivasaragavan and Hitesh Tanenia",

note = "Publisher Copyright: {\textcopyright} 2026. The Author(s). Published by the American Astronomical Society.",

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doi = "10.3847/2041-8213/ae2a20",

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T2 - An Off-axis Short GRB with a Long-lived Afterglow Plateau

AU - Swain, Vishwajeet

AU - Ahumada, Tomás

AU - Patil, Sameer K.

AU - Wagh, Yogesh

AU - Bhalerao, Varun

AU - Nakar, Ehud

AU - Kasliwal, Mansi

AU - Hall, Xander J.

AU - Busmann, Malte

AU - Pathak, Utkarsh

AU - Anand, Shreya

AU - Karambelkar, Viraj

AU - Andreoni, Igor

AU - Anupama, G. C.

AU - Arya, Anuraag

AU - Balasubramanian, Arvind

AU - Barway, Sudhanshu

AU - Carney, Jonathan

AU - Coughlin, Michael

AU - Eappachen, D.

AU - Freeburn, James

AU - Gruen, Daniel

AU - Mohan, Tanishk

AU - O’Connor, Brendan

AU - Palmese, Antonella

AU - Sahu, D. K.

AU - Saikia, Aditya Pawan

AU - Sarin, Nikhil

AU - Srinivasaragavan, Gokul

AU - Tanenia, Hitesh

PY - 2026/1/10

Y1 - 2026/1/10

N2 - 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 (θc ≈ 0. °7) viewed at a modest angle (θv ≈ 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.

AB - 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 (θc ≈ 0. °7) viewed at a modest angle (θv ≈ 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.

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JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L38

ER -

GRB 250704B: An Off-axis Short GRB with a Long-lived Afterglow Plateau

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