Late-Time VLA Reobservations Rule Out ULIRG-Like Host Galaxies For Most Pre-Swift Long-Duration Gamma-Ray Bursts

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.

Accepted to MNRAS

References in corpus (7)

• UV star-formation rates of GRB host galaxies
• The Dynamics and Afterglow Radiation of Gamma-Ray Bursts. I. Constant Density Medium
• The nature of GRB-selected submillimeter galaxies: hot and young
• The optically unbiased GRB host (TOUGH) survey. VI. Radio observations at z<1 and consistency with typical star-forming galaxies
• Probing dust-obscured star formation in the most massive Gamma-Ray Burst host galaxies
• Herschel observations of gamma-ray burst host galaxies: implications for the topology of the dusty interstellar medium
• Another short-burst host galaxy with an optically obscured high star formation rate: The case of GRB 071227

Cited by in corpus (8)

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• Observational Evidence For Constant Gas Accretion Rate Since z = 5
• Galaxy Formation and Symbiotic Evolution with the Inter-Galactic Medium in the Age of ELT-ANDES
• Gamma-ray burst taxonomy: looking for the third class on the spectral peak energy-duration plane in the rest frame
• Finding LoTSS of hosts for GRBs: a search for galaxy - gamma-ray burst coincidences at low frequencies with LOFAR
• Deep ATCA and VLA radio observations of short-GRB host galaxies. Constraints on star-formation rates, afterglow flux, and kilonova radio flares
• A Radio-selected Population of Dark, Long Gamma-ray Bursts: Comparison to the Long Gamma-ray Burst Population and Implications for Host Dust Distributions