|
| | | | |
| | | |
| Stat |
Members: 3645
Articles: 2'501'711
Articles rated: 2609
20 April 2024 |
|
| | | | |
|
Article overview
| |
|
|
Missing Molecular Hydrogen and the Physical Conditions of GRB Host Galaxies | | Jason Tumlinson
; Jason X. Prochaska
; Hsiao-Wen Chen
; Miroslava Dessauges-Zavadsky
; Joshua S. Bloom
; | | Date: |
26 Mar 2007 | | Abstract: | We examine the abundance of molecular hydrogen (H2) in the spectra of gamma ray burst afterglows (GRBs). In nearby galaxies H2 traces the cold neutral medium (CNM) and dense molecular star-forming interstellar gas. Though H2 is detected in at least half of all sightlines towards hot stars in the Magellanic Clouds and in ~25% of damped Lya systems toward quasars, it is not detected in any of the five GRB environments with a similar range of neutral hydrogen column and metallicity. We detect no vibrationally-excited H2 that would imply the GRB itself has photodissociated its parent molecular cloud, so such models are ruled out unless the parent cloud was <~4 pc in radius and was fully dissociated prior to the spectroscopic observations, or the star escaped its parent cloud during its main-sequence lifetime. The low molecular fractions for the GRBs are mysterious in light their large column densities of neutral H and expectations based on local analogs, i.e. 30 Doradus in the LMC. This surprising lack of H2 in GRB-DLAs indicates that the destruction processes that suppress molecule formation in the LMC and SMC are more effective in the GRB hosts, most probably a combination of low metallicity and an FUV radiation field 10--100 times the Galactic mean field. These inferred conditions place strong constraints on the star forming regions in these early galaxies. | | Source: | arXiv, astro-ph/0703666 | | Services: | Forum | Review | PDF | Favorites | |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
browser Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
|
| |
|
|
|
|
News, job offers and information for researchers and scientists:
| |
REGISTER