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|Title:||Late-Time VLA Reobservations Rule Out ULIRG-Like Host Galaxies For Most Pre-Swift Long-Duration Gamma-Ray Bursts|
|Authors:||Perley, D. A.|
Tanvir, Nial R.
Perley, R. A.
|Publisher:||Oxford University Press (OUP), Royal Astronomical Society|
|Citation:||Monthly Notices of the Royal Astronomical Society (February 11, 2017) 465 (1): 970-977.|
|Abstract:||We present new Jansky Very Large Array observations of five pre-Swift gamma-ray bursts for which an ultraluminous (SFR > 100 M_sun/yr) dusty host galaxy had previously been inferred from radio or submillimetre observations taken within a few years after the burst. In four of the five cases we no longer detect any source at the host location to limits much fainter than the original observations, ruling out the existence of an ultraluminous galaxy hosting any of these GRBs. We continue to detect a source at the position of GRB 980703, but it is much fainter than it was a decade ago and the inferred radio star-formation rate (~80 M_sun) is relatively modest. The radio flattening at 200-1000 days observed in the light curve of this GRB may have been caused by a decelerating counterjet oriented 180 degrees away from the viewer, although an unjetted wind model can also explain the data. Our results eliminate all well-established pre-Swift ULIRG hosts, and all cases for which an unobscured GRB was found in a galaxy dominated by heavily-obscured star-formation. When GRBs do occur in ULIRGs the afterglow is almost always observed to be heavily obscured, consistent with the large dust opacities and high dust covering fractions characteristic of these systems.|
|Rights:||Creative Commons “Attribution Non-Commercial No Derivatives” licence CC BY-NC-ND, further details of which can be found via the following link: http://creativecommons.org/licenses/by-nc-nd/4.0/ Archived with reference to SHERPA/RoMEO and publisher website.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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