[FPSPACE] Climatic and Biogeochemical Effects of a Galactic Gamma-Ray Burst

[LARRY KLAES]

Paper: astro-ph/0503625
replaced with revised version Mon, 27 Jun 2005 16:45:03 GMT (202kb)

Title: Climatic and Biogeochemical Effects of a Galactic Gamma-Ray Burst

Authors: Adrian L. Melott, Brian C. Thomas, Daniel P. Hogan, Larissa M. 
Ejzak
(University of Kansas) and Charles H. Jackman (NASA Goddard)
Comments: 12 pages, 2 figures, in press at Geophysical Research Letters. 
Minor
revisions, including details on falsifying the hypothesis
Subj-class: Astrophysics; Atmospheric and Oceanic Physics; Biological 
Physics;
Geophysics; Space Physics; Populations and Evolution

It is likely that one or more gamma-ray bursts within our galaxy have 
strongly irradiated the Earth in the last Gy. This produces significant 
atmospheric ionization and dissociation, resulting in ozone depletion and 
DNA-damaging ultraviolet solar flux reaching the surface for up to a decade. 
Here we show the first detailed computation of two other significant 
effects. Visible opacity of NO2 is sufficient to reduce solar energy at the 
surface up to a few percent, with the greatest effect at the poles, which 
may be sufficient to initiate glaciation. Rainout of dilute nitric acid is 
could have been important for a burst nearer than our conservative nearest 
burst. These results support the hypothesis that the characteristics of the 
late Ordovician mass extinction are consistent with GRB initiation.

\\ ( http://arXiv.org/abs/astro-ph/0503625 , 202kb)