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A direct measurement of the dust extinction curve in an intermediate-redshift galaxy

Heng, Kevin and Lazzati, Davide and Perna, Rosalba and Garnavich, Peter and Noriega-Crespo, Alberto and Bersier, David and Matheson, Thomas and Pahre, Michael A. (2008) A direct measurement of the dust extinction curve in an intermediate-redshift galaxy. Astrophysical Journal, 681 (2). pp. 1116-1122. ISSN 0004-637X. doi:10.1086/588279.

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We present a proof-of-concept study that dust extinction curves can be extracted from the infrared (IR), optical, ultraviolet (UV), and X-ray afterglow observations of GRBs without assuming known extinction laws. We focus on GRB 050525A (z = 0.606), for which we also present IR observations from the Spitzer Space Telescope at t = t_(IR) ≈ 2.3 days postburst. We construct the spectral energy distribution of the afterglow at t = t_(IR) and use it to derive the dust extinction curve of the host galaxy in seven optical/UV bands. By comparing our derived extinction curve to known templates, we see that the Galactic or Milky Way extinction laws are disfavored versus those of the Small and Large Magellanic Clouds (SMC and LMC), but that we cannot rule out the presence of a LMC-like 2175 Å bump in our extinction curve. The dust-to-gas ratio present within the host galaxy of GRB 050525A is similar to that found in the LMC, while about 10%-40% more dust is required if the SMC template is assumed. Our method is useful to observatories that are capable of simultaneously observing GRB afterglows in multiple wave bands from the IR to the X-ray.

Item Type:Article
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URLURL TypeDescription
Heng, Kevin0000-0003-1907-5910
Lazzati, Davide0000-0002-9190-662X
Noriega-Crespo, Alberto0000-0002-6296-8960
Matheson, Thomas0000-0001-6685-0479
Additional Information:© 2008 The American Astronomical Society. Received 2008 January 11; accepted 2008 March 17. Print publication: Issue 2 (2008 July 10). K. H. gratefully acknowledges support from the Institute for Advanced Study and benefits from diverse interactions within the astrophysics group. He thanks Brian Schmidt, Alexia Schulz, Mike Fall, Nadia Zakamska, Alex Blustin, and Ralph Wijers for helpful conversations. This work was partially supported by NSF grant NNG05GH55G (R. P. and D. L.). We are indebted to the anonymous referee for the meticulous reading of the manuscript and the useful suggestions that followed, which tremendously improved the quality of the paper.
Funding AgencyGrant Number
Institute for Advanced StudyUNSPECIFIED
Subject Keywords:dust, extinction; galaxies: ISM; gamma rays: bursts
Issue or Number:2
Record Number:CaltechAUTHORS:HENapj08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13446
Deposited By: Tony Diaz
Deposited On:17 Aug 2009 16:29
Last Modified:08 Nov 2021 22:37

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