2014A&A...572A..12F


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST06:23:40

2014A&A...572A..12F - Astronomy and Astrophysics, volume 572A, 12-12 (2014/12-1)

The mysterious optical afterglow spectrum of GRB 140506A at z = 0.889.

FYNBO J.P.U., KRUEHLER T., LEIGHLY K., LEDOUX C., VREESWIJK P.M., SCHULZE S., NOTERDAEME P., WATSON D., WIJERS R.A.M.J., BOLMER J., CANO Z., CHRISTENSEN L., COVINO S., D'ELIA V., FLORES H., FRIIS M., GOLDONI P., GREINER J., HAMMER F., HJORTH J., JAKOBSSON P., JAPELJ J., KAPER L., KLOSE S., KNUST F., LELOUDAS G., LEVAN A., MALESANI D., MILVANG-JENSEN B., MOLLER P., NICUESA GUELBENZU A., OATES S., PIAN E., SCHADY P., SPARRE M., TAGLIAFERRI G., TANVIR N., THOENE C.C., DE UGARTE POSTIGO A., VERGANI S., WIERSEMA K., XU D. and ZAFAR T.

Abstract (from CDS):

Gamma-ray burst (GRB) afterglows probe sightlines to star-forming regions in distant star-forming galaxies. Here we present a study of the peculiar afterglow spectrum of the z=0.889 Swift GRB140506A. Our aim is to understand the origin of the very unusual properties of the absorption along the line of sight. We analyse spectroscopic observations obtained with the X-shooter spectrograph mounted on the ESO/VLT at two epochs 8.8h and 33h after the burst, and with imaging from the GROND instrument. We also present imaging and spectroscopy of the host galaxy obtained with the Magellan telescope. The underlying afterglow appears to be a typical afterglow of a long-duration GRB. However, the material along the line of sight has imprinted very unusual features on the spectrum. First, there is a very broad and strong flux drop below 8000Å (∼4000Å in the rest frame), which seems to be variable between the two spectroscopic epochs. We can reproduce the flux-drops both as a giant 2175Å extinction bump and as an effect of multiple scattering on dust grains in a dense environment. Second, we detect absorption lines from excited HI and HeI. We also detect molecular absorption from CH+. We interpret the unusual properties of these spectra as reflecting the presence of three distinct regions along the line of sight: the excited HeI absorption originates from an HII-region, whereas the Balmer absorption must originate from an associated photodissociation region. The strong metal line and molecular absorption and the dust extinction must originate from a third, cooler region along the line of sight. The presence of at least three separate regions is reflected in the fact that the different absorption components have different velocities relative to the systemic redshift of the host galaxy.

Abstract Copyright:

Journal keyword(s): gamma-ray burst: individual: GRB140506A - ISM: abundances - dust, extinction - ISM: molecules

VizieR on-line data: <Available at CDS (J/A+A/572/A12): ep1nir.dat ep1ubv.dat ep1vis.dat ep2nir.dat ep2uvb.dat ep2vis.dat>

Simbad objects: 13

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Number of rows : 13

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 GRB 021004 gB 00 26 54.68 +18 55 41.6           ~ 515 1
2 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10905 1
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9446 1
4 GRB 070318 gB 03 13 56.830 -42 56 46.30 18.27 16.23 15.49     ~ 139 0
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14832 1
6 NAME Trapezium Cluster As* 05 35 16.5 -05 23 14           ~ 1467 1
7 SN 2014J SN* 09 55 42.12 +69 40 25.9           SNIa 317 1
8 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5336 6
9 NGC 3293 OpC 10 35 49 -58 13.8   4.84 4.7     ~ 282 0
10 HD 105183 HS* 12 06 47.2351675221 +11 40 12.658737086   10.93 11.06     sdB8IIIHe2 104 0
11 NGC 4755 OpC 12 53 39 -60 21.7           ~ 268 0
12 M 16 OpC 18 18 48 -13 48.4   6.58 6.0     ~ 935 2
13 GRB 140506A gB 18 27 06.04 -55 38 08.7           ~ 51 0

    Equat.    Gal    SGal    Ecl

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2020.07.13-06:23:40

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