2011A&A...532A.143Z


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.14CEST18:36:53

2011A&A...532A.143Z - Astronomy and Astrophysics, volume 532A, 143-143 (2011/8-1)

The extinction curves of star-forming regions from z = 0.1 to 6.7 using GRB afterglow spectroscopy.

ZAFAR T., WATSON D., FYNBO J.P.U., MALESANI D., JAKOBSSON P. and DE UGARTE POSTIGO A.

Abstract (from CDS):

Studies of extinction curves provide insights into the properties of interstellar dust. Until recently, however, very few extinction curves existed outside the local group. GRB afterglows are well suited to extinction studies due to their brightness, simple power-law spectra and their occurrence in distant star forming galaxies. In this paper we present results from the SED analysis of a sample of 41 GRB afterglows, from X-ray to NIR wavelengths. The sample is based on spectra from VLT-FORS, with additional data primarily from Swift. This is the largest sample of extinction curves outside the Local Group and, to date, the only extragalactic sample of absolute extinction curves based on spectroscopy. Estimates of the distribution of restframe visual extinctions, the extinction curves, and the intrinsic spectral shapes of GRB afterglows are obtained. Their correlation with HI column density as well as total and gas-phase metal column density are examined. The line-of-sight gas-to-dust and metals-to-dust ratios are determined and examined as a function of total column density, ISM metallicity and redshift. The intrinsic SEDs of the afterglows show that approximately half the sample require a cooling break between the optical and X-ray ranges. The broken power-law SEDs show an average change in the spectral index of Δβ=0.51 with a very small standard deviation of 0.02 (excluding the outlier GRB080210). This is consistent with the expectations from a simple synchrotron model. Such a close convergence of values suggests that the X-ray afterglows of GRBs may be used with considerably more confidence to set the absolute flux level and intrinsic spectral indices in the optical and UV. Of the sample, 63% are well described by a featureless (SMC-type) extinction curve. Almost a quarter of our sample is consistent with no significant extinction (typically AVλ0.1). The 2175Å extinction bump is detected unequivocally in 7% of our sample (3 GRBs), which all have AV >1.0, while one afterglow has a very unusual extinction curve with a sharp UV rise. However, we can only say that the bump is not present in about a quarter of our sample because of low extinction or lack of coverage of the 2200Å region. All the afterglows well fit with SMC type curves have moderate or low extinction, with AV<0.65. This suggests that the SMC extinction curve is not as nearly-universal as previously believed and that extinction curves more similar to those found in the Galaxy and the LMC may be quite prevalent. We find an anti-correlation between gas-to-dust ratio and metallicity consistent with the Local Group relation; we find, however, no correlation between the metals-to-dust ratios and the metallicities, redshift and visual extinction; we find no strong correlation of the extinction column with metallicity either. Our metals-to-dust ratios derived from the soft X-ray absorption are always larger (3-30 times) than the Local Group value, which may mean that GRB hosts may be less efficient at turning their metals into dust. However, we find that gas, dust, and metal column densities are all likely to be influenced by photo-ionization and dust destruction effects from the GRB to differing extents and caution must be used in extrapolating the ratios of dust and gas-derived properties from GRB afterglows to the star-forming population in general.

Abstract Copyright:

Journal keyword(s): galaxies: high-redshift - dust, extinction - gamma-ray burst: general

Simbad objects: 60

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Number of rows : 60

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 070110 gB 00 03 39.270 -52 58 27.00 21.8 21.9 21.2     ~ 170 0
2 GRB 070611 gB 00 07 58.000 -29 45 19.40           ~ 79 0
3 GRB 071031 gB 00 25 37.40 -58 03 33.9           ~ 142 0
4 GRB 060708 gB 00 31 13.850 -33 45 32.40 19.07 19.79 17.37     ~ 83 0
5 GRB 050824 gB 00 48 56.100 +22 36 32.00 19.66 21.03 20.46     ~ 156 0
6 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9446 1
7 GRB 050904 gB 00 54 50.794 +14 05 09.42           ~ 431 1
8 GRB 060719 gB 01 13 43.380 -48 22 55.09           ~ 81 0
9 GRB 080523 gB 01 23 11.53 -64 01 50.9           ~ 30 0
10 GRB 080707 gB 02 10 28.48 +33 06 35.1           ~ 62 0
11 GRB 070721B gB 02 12 32.98 -02 11 39.8           ~ 98 0
12 GRB 070802 gB 02 27 35.91 -55 31 39.1           ~ 136 0
13 GRB 070129 gB 02 28 00.940 +11 41 04.00       21.3   ~ 93 0
14 GRB 080411 gB 02 31 54.82 -71 18 07.5           ~ 80 0
15 GRB 071112C gB 02 36 50.89 +28 22 16.9           ~ 129 0
16 GRB 060906 gB 02 43 00.900 +30 21 42.12     19.84     ~ 116 0
17 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5669 1
18 GRB 061007 gB 03 05 19.510 -50 30 02.50 14.28 14.40 12.95     ~ 269 1
19 GRB 070318 gB 03 13 56.830 -42 56 46.30 18.27 16.23 15.49     ~ 139 0
20 GRB 060115 gB 03 36 08.400 +17 20 43.00           ~ 146 0
21 GRB 060904B gB 03 52 50.520 -00 43 30.61 18.27 19.14 18.37     ~ 162 0
22 GRB 080913 gB 04 22 57.90 -25 07 38.6           ~ 174 0
23 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14832 1
24 GRB 080928 gB 06 20 16.85 -55 11 59.3           ~ 128 1
25 GRB 060729 gB 06 21 31.850 -62 22 12.69           ~ 247 0
26 GRB 070411 gB 07 09 19.930 +01 03 52.60     17.94     ~ 113 0
27 GRB 070125 gB 07 51 17.80 +31 09 04.8           ~ 155 0
28 GRB 071020 gB 07 58 39.65 +32 51 38.8           ~ 133 0
29 GRB 061021 gB 09 40 36.120 -21 57 05.40 18.21 19.20 16.82     ~ 125 0
30 GRB 070306 gB 09 52 23.220 +10 28 55.20           ~ 177 1
31 GRB 080607 gB 12 59 47.14 +15 55 09.6           ~ 209 0
32 GRB 060512 gB 13 03 05.810 +41 11 27.21 19.12 19.63 17.20     ~ 120 0
33 GRB 060206 gB 13 31 43.420 +35 03 03.60   19.99 17.09     ~ 282 1
34 GRB 050730 gB 14 08 17.090 -03 46 18.90   20.32 17.68     ~ 282 1
35 GRB 080319B gB 14 31 41.04 +36 18 09.2           ~ 421 0
36 GRB 080721 gB 14 57 55.76 -11 43 24.9           ~ 140 0
37 GRB 060714 gB 15 11 26.450 -06 33 58.30   20.21 18.54     ~ 164 0
38 GRB 060526 gB 15 31 18.360 +00 17 04.90   18.31 17.16     ~ 233 0
39 GRB 060418 gB 15 45 42.600 -03 38 20.00 15.73 16.19 14.98     ~ 322 1
40 GRB 050401 gB 16 31 28.84 +02 11 14.5           ~ 302 0
41 GRB 080210 gB 16 45 04.03 +13 49 36.3           ~ 92 0
42 GRB 060807 gB 16 50 02.600 +31 35 30.70           ~ 53 0
43 GRB 080605 gB 17 28 30.04 +04 00 56.9           ~ 153 0
44 GRB 060926 gB 17 35 43.660 +13 02 18.60     19.36     ~ 116 0
45 GRB 080520 gB 18 40 46.50 -54 59 30.4           ~ 56 0
46 GRB 080905B gB 20 06 57.90 -62 33 46.4           ~ 80 0
47 GRB 070508 gB 20 51 11.810 -78 23 04.88     19.62     ~ 112 0
48 GRB 080805 gB 20 56 55.30 -62 25 58.8           ~ 79 0
49 GRB 060614 gB 21 23 32.140 -53 01 36.10 18.89 20.12 19.54     ~ 507 1
50 GRB 061110B gB 21 35 40.400 +06 52 34.10           ~ 75 0
51 GRB 080413B gB 21 44 34.62 -19 58 51.2           ~ 148 0
52 GRB 060927A gB 21 58 11.930 +05 21 50.32           ~ 173 0
53 GRB 071117 gB 22 20 10.40 -63 26 36.6           ~ 88 0
54 GRB 080916A gB 22 25 09.30 -57 01 33.7           ~ 139 0
55 GRB 061110A gB 22 25 09.800 -02 15 30.70 21.43         ~ 115 0
56 GRB 071021 gB 22 42 34.34 +23 43 05.4           ~ 80 0
57 GRB 070506 gB 23 08 52.390 +10 43 20.30     19.04     ~ 70 0
58 GRB 071025 gB 23 40 17.02 +31 46 42.4           ~ 95 0
59 GRB 060707 gB 23 48 19.000 -17 54 17.00     19.79     ~ 135 0
60 NAME Local Group GrG ~ ~           ~ 6973 0

    Equat.    Gal    SGal    Ecl

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2020.07.14-18:36:53

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