Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-05-21
Astronomy and Astrophysics
Astrophysics
14 pages, no figures, submitted to The Astrophysical Journal
Scientific paper
10.1086/323858
According to recent models, gamma-ray bursts apparently explode in a wide variety of ambient densities ranging from ~ 10^{-3} to 30 cm^{-3}. The lowest density environments seem, at first sight, to be incompatible with bursts in or near molecular clouds or with dense stellar winds and hence with the association of gamma-ray bursts with massive stars. We argue that low ambient density regions naturally exist in areas of active star formation as the interiors of superbubbles. The evolution of the interior bubble density as a function of time for different assumptions about the evaporative or hydrodynamical mass loading of the bubble interior is discussed. We present a number of reasons why there should exist a large range of inferred afterglow ambient densities whether gamma-ray bursts arise in massive stars or some version of compact star coalescence. We predict that many gamma-ray bursts will be identified with X-ray bright regions of galaxies, corresponding to superbubbles, rather than with blue localized regions of star formation. Massive star progenitors are expected to have their own circumstellar winds. The lack of evidence for individual stellar winds associated with the progenitor stars for the cases with afterglows in especially low density environments may imply low wind densities and hence low mass loss rates combined with high velocities. If gamma-ray bursts are associated with massive stars, this combination might be expected for compact progenitors with atmospheres dominated by carbon, oxygen or heavier elements, that is, progenitors resembling Type Ic supernovae.
Scalo John
Wheeler Justin C.
No associations
LandOfFree
Pre-Existing Superbubbles as the Sites of Gamma-Ray Bursts does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Pre-Existing Superbubbles as the Sites of Gamma-Ray Bursts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pre-Existing Superbubbles as the Sites of Gamma-Ray Bursts will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-563932