Radio Constraints on Heavily Obscured Star Formation within Dark Gamma-Ray Burst Host Galaxies
- Creators
- Perley, D. A.
- Perley, R. A.
Abstract
Highly dust-obscured starbursting galaxies (submillimeter galaxies and their ilk) represent the most extreme sites of star formation in the distant universe and contribute significantly to overall cosmic star formation beyond z > 1.5. Some stars formed in these environments may also explode as gamma-ray bursts (GRBs) and contribute to the population of "dark" bursts. Here we present Very Large Array wideband radio-continuum observations of 15 heavily dust-obscured Swift GRBs to search for radio synchrotron emission associated with intense star formation in their host galaxies. Most of these targets (11) are not detected. Of the remaining four objects, one detection is marginal, and for two others we cannot yet rule out the contribution of a long-lived radio afterglow. The final detection is secure, but indicates a star formation rate (SFR) roughly consistent with the dust-corrected UV-inferred value. Most galaxies hosting obscured GRBs are therefore not forming stars at extreme rates, and the amount of optical extinction seen along a GRB afterglow sightline does not clearly correlate with the likelihood that the host has a sufficiently high SFR to be radio-detectable. While some submillimeter galaxies do readily produce GRBs, these GRBs are often not heavily obscured—suggesting that the outer (modestly obscured) parts of these galaxies overproduce GRBs and the inner (heavily obscured) parts underproduce GRBs relative to their respective contributions to star formation, hinting at strong chemical or initial mass function gradients within these systems.
Additional Information
© 2013 The American Astronomical Society. Received 2013 May 13; accepted 2013 October 23; published 2013 November 13. We thank the referee for many helpful suggestions that improved the content and readability of this manuscript. We also acknowledge helpful comments from M. Michałowski, Tanvir. We further thank D. Frail for sharing the database of GRB afterglow radio light curves. Support for this work was provided by NASA through Hubble Fellowship grant HST-HF-51296.01- A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Facility: VLAAttached Files
Published - 0004-637X_778_2_172.pdf
Submitted - 1305.2941v3.pdf
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Additional details
- Eprint ID
- 43232
- Resolver ID
- CaltechAUTHORS:20140106-135959796
- HST-HF-51296.01-A
- NASA Hubble Fellowship
- NAS 5-26555
- NASA
- Created
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2014-01-07Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field