The host galaxy of GRB 980425/SN1998bw: a collisional ring galaxy
Date Issued
2019
Author(s)
Arabsalmani, M.
•
Roychowdhury, S.
•
Starkenburg, T. K.
•
Christensen, L.
•
Le Floc'h, E.
•
Kanekar, N.
•
Bournaud, F.
•
Zwaan, M. A.
•
Fynbo, J. P. U.
•
Møller, P.
•
Abstract
We report Giant Metrewave Radio Telescope (GMRT), Very Large Telescope (VLT), and Spitzer Space Telescope observations of ESO 184-G82, the host galaxy of GRB 980425/SN 1998bw, that yield evidence of a companion dwarf galaxy at a projected distance of 13 kpc. The companion, hereafter GALJ193510-524947, is a gas-rich, star-forming galaxy with a star formation rate of 0.004 M_{☉ } yr^{-1}, a gas mass of 10^{7.1± 0.1} M_{☉}, and a stellar mass of 10^{7.0± 0.3} M_{☉}. The interaction between ESO 184-G82 and GALJ193510-524947 is evident from the extended gaseous structure between the two galaxies in the GMRT H I 21 cm map. We find a ring of high column density H I gas, passing through the actively star-forming regions of ESO 184-G82 and the GRB location. This ring lends support to the picture in which ESO 184-G82 is interacting with GALJ193510-524947. The massive stars in GALJ193510-524947 have similar ages to those in star-forming regions in ESO 184-G82, also suggesting that the interaction may have triggered star formation in both galaxies. The gas and star formation properties of ESO 184-G82 favour a head-on collision with GALJ193510-524947 rather than a classical tidal interaction. We perform state-of-the-art simulations of dwarf-dwarf mergers and confirm that the observed properties of ESO 184-G82 can be reproduced by collision with a small companion galaxy. This is a very clear case of interaction in a gamma-ray burst host galaxy and of interaction-driven star formation giving rise to a gamma-ray burst in a dense environment.
Volume
485
Issue
4
Start page
5411
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.485.5411A
Rights
open.access
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