The luminous host galaxy, faint supernova and rapid afterglow rebrightening of GRB 100418A
Journal
Date Issued
2018
Author(s)
de Ugarte Postigo, A.
•
Thöne, C. C.
•
Bensch, K.
•
van der Horst, A. J.
•
Kann, D. A.
•
Cano, Z.
•
Izzo, L.
•
Goldoni, P.
•
Martín, S.
•
Filgas, R.
•
Schady, P.
•
Gorosabel, J.
•
Bikmaev, I.
•
Bremer, M.
•
Burenin, R.
•
Castro-Tirado, A. J.
•
•
Fynbo, J. P. U.
•
Garcia-Appadoo, D.
•
de Gregorio-Monsalvo, I.
•
Jelínek, M.
•
Khamitov, I.
•
Kamble, A.
•
Kouveliotou, C.
•
Krühler, T.
•
Leloudas, G.
•
Melnikov, S.
•
Nardini, M.
•
Perley, D. A.
•
Petitpas, G.
•
Pooley, G.
•
Rau, A.
•
Rol, E.
•
Sánchez-Ramírez, R.
•
Starling, R. L. C.
•
Tanvir, N. R.
•
Wiersema, K.
•
Wijers, R. A. M. J.
•
Zafar, T.
Abstract
Context. Long gamma-ray bursts (GRBs) give us the chance to study both their extreme physics and the star-forming galaxies in which they form.
Aims: GRB 100418A, at a redshift of z = 0.6239, had a bright optical and radio afterglow, and a luminous star-forming host galaxy. This allowed us to study the radiation of the explosion as well as the interstellar medium of the host both in absorption and emission.
Methods: We collected photometric data from radio to X-ray wavelengths to study the evolution of the afterglow and the contribution of a possible supernova (SN) and three X-shooter spectra obtained during the first 60 h.
Results: The light curve shows a very fast optical rebrightening, with an amplitude of ∼3 magnitudes, starting 2.4 h after the GRB onset. This cannot be explained by a standard external shock model and requires other contributions, such as late central-engine activity. Two weeks after the burst we detect an excess in the light curve consistent with a SN with peak absolute magnitude MV = -18.5 mag, among the faintest GRB-SNe detected to date. The host galaxy shows two components in emission, with velocities differing by 130 km s-1, but otherwise having similar properties. While some absorption and emission components coincide, the absorbing gas spans much higher velocities, indicating the presence of gas beyond the star-forming regions. The host has a star formation rate of SFR = 12.2 M☉ yr-1, a metallicity of 12 + log(O/H) = 8.55, and a mass of 1.6 × 109 M☉.
Conclusions: GRB 100418A is a member of a class of afterglow light curves which show a steep rebrightening in the optical during the first day, which cannot be explained by traditional models. Its very faint associated SN shows that GRB-SNe can have a larger dispersion in luminosities than previously seen. Furthermore, we have obtained a complete view of the host of GRB 100418A owing to its spectrum, which contains a remarkable number of both emission and absorption lines.
Aims: GRB 100418A, at a redshift of z = 0.6239, had a bright optical and radio afterglow, and a luminous star-forming host galaxy. This allowed us to study the radiation of the explosion as well as the interstellar medium of the host both in absorption and emission.
Methods: We collected photometric data from radio to X-ray wavelengths to study the evolution of the afterglow and the contribution of a possible supernova (SN) and three X-shooter spectra obtained during the first 60 h.
Results: The light curve shows a very fast optical rebrightening, with an amplitude of ∼3 magnitudes, starting 2.4 h after the GRB onset. This cannot be explained by a standard external shock model and requires other contributions, such as late central-engine activity. Two weeks after the burst we detect an excess in the light curve consistent with a SN with peak absolute magnitude MV = -18.5 mag, among the faintest GRB-SNe detected to date. The host galaxy shows two components in emission, with velocities differing by 130 km s-1, but otherwise having similar properties. While some absorption and emission components coincide, the absorbing gas spans much higher velocities, indicating the presence of gas beyond the star-forming regions. The host has a star formation rate of SFR = 12.2 M☉ yr-1, a metallicity of 12 + log(O/H) = 8.55, and a mass of 1.6 × 109 M☉.
Conclusions: GRB 100418A is a member of a class of afterglow light curves which show a steep rebrightening in the optical during the first day, which cannot be explained by traditional models. Its very faint associated SN shows that GRB-SNe can have a larger dispersion in luminosities than previously seen. Furthermore, we have obtained a complete view of the host of GRB 100418A owing to its spectrum, which contains a remarkable number of both emission and absorption lines.
This work makes use of data obtained at the following telescopes/observatories: VLT/Paranal (proposals 085.A-0009, 085.D-0773), GTC/ORM (proposals GTC74-10A, GTCMULTIPLE2B-17A), Keck/MK, Subaru/MK, 3.5m/CAHA, UKIRT/MK, WHT/ORM, RTT150/TUBITAK, Spitzer, PdBI/IRAM, WSRT/RO, Ryle/MRAO, and SMA/MK.
Volume
620
Start page
A190
Issn Identifier
0004-6361
Ads BibCode
2018A&A...620A.190D
Rights
open.access
File(s)![Thumbnail Image]()
Loading...
Name
aa33636-18.pdf
Description
PDF editoriale
Size
3.35 MB
Format
Adobe PDF
Checksum (MD5)
f5d541f882f8aa660312a4b3618dbcda