Late-time JWST/NIRCam Observations of the Extremely Long-duration GRB 250702B/EP 250702a and Its Host Galaxy
Huei Sears, Jean J. Somalwar, Ryan Chornock, Tanmoy Laskar, Andrew Levan, Raffaella Margutti, Brendan O'Connor, Nayana A. J., Tomas Ahumada, Kate D. Alexander, Igor Andreoni, Akash Anumarlapudi, Jonathan Carney, James Freeburn, Lluís Galbany, Benjamin P. Gompertz, Or Graur, Saarah Hall, Xander J. Hall, Erica Hammerstein, Saurabh W. Jha, Mansi M. Kasliwal, Dheeraj Pasham, Itai Sfaradi, Yuhan Yao
astro-ph.HE, astro-ph.SR
Submitted: 2026-06-16
Comments: 18 pages, 10 figures
License: http://creativecommons.org/licenses/by/4.0/
The gist: We present JWST/NIRCam observations of the extremely long-duration gamma-ray burst (GRB) 250702B taken at 95 days post-GRB (observer frame).
Terminology
Abstract
We present JWST/NIRCam observations of the extremely long-duration gamma-ray burst (GRB) 250702B taken at 95 days post-GRB (observer frame). The observations of the host galaxy reveal a single galaxy with a prominent dust lane observed nearly edge-on. Prospector modeling of the host galaxy photometry finds a high stellar mass (log(M*/M Sun) = 11.0 +0.2/-0.3) and large dust column (A V = 2.8 +/- 0.3 mag), in agreement with previous results. If GRB 250702B is a collapsar-driven GRB, the host galaxy is the brightest (in rest-frame r and rest-frame H) and most massive compared to GRB hosts at similar redshifts. The transient localization is near the dust lane, and while we find no evidence for transient emission in F277W, F356W, and F444W, forced photometry in F150W and F200W reveals possible 3 sigma detections of the transient at m F150W 27.9 AB mag and m F200W 27.4 AB mag. If these are secure detections, they are indicative of a late-time light curve flattening. This behavior is consistent with that of jetted tidal disruption events (TDEs); however, it is also consistent with a supernova plus GRB afterglow model. Alternatively, if these are upper limits, they are consistent with, but do not further constrain, the extrapolated power-law decline of the afterglow. The ambiguity of the possible detection of the transient in F150W and F200W highlights the need for late-time template observations with JWST/NIRCam.
Sources
- An Intermediate-mass Black Hole Lurking in A Galactic Halo Caught Alive during Outburst
- VLA Observations Confirm AT 2023mfm as an Off-nuclear Tidal Disruption Event
- TDE 2025abcr: A Tidal Disruption Event in the Outskirts of a Massive Galaxy
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