Terrestrial Ozone Depletion due to a Milky Way Gamma-Ray Burst
Abstract
Based on cosmological rates, it is probable that at least once in the last gigayear the Earth has been irradiated by a gamma-ray burst (GRB) in our Galaxy from within 2 kpc. We have performed the first detailed computation of the effects on the Earth's atmosphere of one such impulsive event: A 10 s 100 kJ m-2 burst penetrates to the stratosphere causing globally averaged ozone depletion of 35%, with depletion reaching 55% at some latitudes. Significant depletion persists for over 5 years after the burst. A 50% decrease in ozone column density leads to approximately 3 times the normal UVB (280-315 nm; a wavelength band that ozone significantly absorbs and that living organisms are sensitive to) flux, and widespread extinctions are likely, based on extrapolation from sensitivity of modern organisms. Additional effects include a shot of nitrate fertilizer and NO2 opacity in the visible, providing a cooling perturbation to the climate over a similar timescale. These results lend support to the hypothesis that a GRB may have initiated the late Ordovician mass extinction (Melott et al.).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2005
- DOI:
- 10.1086/429799
- arXiv:
- arXiv:astro-ph/0411284
- Bibcode:
- 2005ApJ...622L.153T
- Keywords:
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- Astrobiology;
- Gamma Rays: Bursts;
- Astrophysics;
- Physics - Atmospheric and Oceanic Physics;
- Physics - Geophysics;
- Physics - Space Physics;
- Quantitative Biology - Populations and Evolution
- E-Print:
- 4 color figures