Colour variations in the GRB 120327A afterglow

DOI: 
10.1051/0004-6361/201731759
Publication date: 
01/10/2017
Main author: 
Melandri, A.
IAA authors: 
Gorosabel, J.
Authors: 
Melandri, A.;Covino, S.;Zaninoni, E.;Campana, S.;Bolmer, J.;Cobb, B. E.;Gorosabel, J.;Kim, J. -W.;Kuin, P.;Kuroda, D.;Malesani, D.;Mundell, C. G.;Nappo, F.;Sbarufatti, B.;Smith, R. J.;Steele, I. A.;Topinka, M.;Trotter, A. S.;Virgili, F. J.;Bernardini, M. G.;D'Avanzo, P.;D'Elia, V.;Fugazza, D.;Ghirlanda, G.;Gomboc, A.;Greiner, J.;Guidorzi, C.;Haislip, J. B.;Hanayama, H.;Hanlon, L.;Im, M.;Ivarsen, K. M.;Japelj, J.;Jelínek, M.;Kawai, N.;Kobayashi, S.;Kopac, D.;LaCluyzé, A. P.;Martin-Carrillo, A.;Murphy, D.;Reichart, D. E.;Salvaterra, R.;Salafia, O. S.;Tagliaferri, G.;Vergani, S. D.
Journal: 
Astronomy and Astrophysics
Refereed: 
Yes
Publication type: 
Article
Volume: 
607
Pages: 
A29
Abstract: 

<BR /> Aims: We present a comprehensive temporal and spectral analysis of the long Swift GRB 120327A afterglow data to investigate possible causes of the observed early-time colour variations. <BR /> Methods: We collected data from various instruments and telescopes in X-ray, ultraviolet, optical, and near-infrared bands, and determined the shapes of the afterglow early-time light curves. We studied the overall temporal behaviour and the spectral energy distributions from early to late times. <BR /> Results: The ultraviolet, optical, and near-infrared light curves can be modelled with a single power-law component between 200 and 2 × 10<SUP>4</SUP> s after the burst event. The X-ray light curve shows a canonical steep-shallow-steep behaviour that is typical of long gamma-ray bursts. At early times a colour variation is observed in the ultraviolet/optical bands, while at very late times a hint of a re-brightening is visible. The observed early-time colour change can be explained as a variation in the intrinsic optical spectral index, rather than an evolution of the optical extinction. Table 2 is only available at the CDS via anonymous ftp to <A href='http://cdsarc.u-strasbg.fr'>http://cdsarc.u-strasbg.fr</A> (<A href='http://130.79.128.5'>http://130.79.128.5</A>) or via <A href='http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/607/A29'>http://cdsarc.u-s...

Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032641680&doi=10.1051%2f0004-6361%2f201731759&partnerID=40&md5=6279996a494c7fc8fbca74caf3d057ba
ADS Bibcode: 
2017A&A...607A..29M
Keywords: 
gamma-ray burst: individual: GRB 120327A;dust;extinction