2012ApJ...753...82Z


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.02CET14:07:13

2012ApJ...753...82Z - Astrophys. J., 753, 82 (2012/July-1)

The properties of the 2175 Å extinction feature discovered in GRB afterglows.

ZAFAR T., WATSON D., ELIASDOTTIR A., FYNBO J.P.U., KRUHLER T., SCHADY P., LELOUDAS G., JAKOBSSON P., THONE C.C., PERLEY D.A., MORGAN A.N., BLOOM J. and GREINER J.

Abstract (from CDS):

The unequivocal, spectroscopic detection of the 2175 Å bump in extinction curves outside the Local Group is rare. To date, the properties of the bump have been examined in only two gamma-ray burst (GRB) afterglows (GRB 070802 and GRB 080607). In this work, we analyze in detail the detections of the 2175 Å extinction bump in the optical spectra of two further GRB afterglows: GRB 080605 and 080805. We gather all available optical/near-infrared photometric, spectroscopic, and X-ray data to construct multi-epoch spectral energy distributions (SEDs) for both GRB afterglows. We fit the SEDs with the Fitzpatrick & Massa model with a single or broken power law. We also fit a sample of 38 GRB afterglows, known to prefer a Small Magellanic Cloud (SMC)-type extinction curve, with the same model. We find that the SEDs of GRB 080605 and GRB 080805 at two epochs are fit well with a single power law with a derived extinction of AV= 0.52+0.13_- 0.16_ and 0.50+0.13_- 0.10_, and 2.1+0.7_- 0.6_ and 1.5±0.2, respectively. While the slope of the extinction curve of GRB 080805 is not well constrained, the extinction curve of GRB 080605 has an unusual very steep far-UV rise together with the 2175 Å bump. Such an extinction curve has previously been found in only a small handful of sightlines in the Milky Way. One possible explanation of such an extinction curve may be dust arising from two different regions with two separate grain populations, however we cannot distinguish the origin of the curve. We finally compare the four 2175 Å bump sightlines to the larger GRB afterglow sample and to Local Group sightlines. We find that while the width and central positions of the bumps are consistent with what is observed in the Local Group, the relative strength of the detected bump (Abump) for GRB afterglows is weaker for a given AV than for almost any Local Group sightline. Such dilution of the bump strength may offer tentative support to a dual dust-population scenario.

Abstract Copyright:

Journal keyword(s): dust, extinction - gamma-ray burst: general - gamma-ray burst: individual (GRB 080605, GRB 080805)

Simbad objects: 21

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Number of rows : 21

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9610 1
2 NAME SMC Bar PoG 01 05 -72.6           ~ 201 0
3 CD-28 595 PM* 01 54 50.2704861570 -27 28 35.740415025   12.06 11.51     ~ 120 0
4 GRB 070802 gB 02 27 35.91 -55 31 39.1           ~ 137 0
5 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5794 1
6 GRB 060210 gB 03 50 57.370 +27 01 34.40   20.27       ~ 225 0
7 HD 29647 * 04 41 08.0445234455 +25 59 33.957034408 9.69 9.22 8.31 7.35 6.60 B9IIIpHgMn 190 0
8 HD 283809 * 04 41 24.7241497431 +25 54 48.382917896 12.64 12.0 10.7     F8 41 0
9 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15064 1
10 NAME LMC 2 Supergiant Shell sh 05 41 27 -69 22.4           ~ 169 0
11 HD 62542 * 07 42 37.2148100663 -42 13 47.830173869   8.21 8.03     B3V 130 0
12 GRB 061121 gB 09 48 54.570 -13 11 42.68 17.19 17.71 17.02     ~ 290 0
13 GRB 080607 gB 12 59 47.14 +15 55 09.6           ~ 210 0
14 GRB 060418 gB 15 45 42.600 -03 38 20.00 15.73 16.19 14.98     ~ 324 1
15 GRB 080605 gB 17 28 30.04 +04 00 56.9           ~ 154 0
16 HD 185418 * 19 38 27.4810594267 +17 15 26.046198639 7 7.639 7.485     B0.5V 119 0
17 GRB 080805 gB 20 56 55.30 -62 25 58.8           ~ 81 0
18 HD 204827 SB* 21 28 57.7601719555 +58 44 23.223287944 8.63 8.74 7.94 7.25 6.76 O9.5IV 306 0
19 HD 210121 * 22 08 11.9025501667 -03 31 52.770012247   7.84 7.68     B7II 152 0
20 LP 877-23 PM* 22 52 41.0353308036 -20 35 32.995847106   13.02 11.90     ~ 104 0
21 NAME Local Group GrG ~ ~           ~ 7115 0

    Equat.    Gal    SGal    Ecl

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2020.12.02-14:07:13

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