1112.1792 (Wilfried F. Domainko)
Wilfried F. Domainko
Nearby, Galactic gamma-ray bursts (GRBs) may affect the terrestrial biota if
their radiation is beamed towards the Earth. Compact stellar binary mergers are
possible central engines of short GRBs and their rate could be boosted in
globular clusters. Globular cluster typically follow well defined orbits around
the galactic center. Therefore their position relative to the solar system can
be calculated back in time. This fact is used to demonstrate that globular
cluster - solar system encounters define possible points in time when a nearby
GRB could have exploded. Additionally, potential terrestrial signatures in the
geological record connected to such an event are discussed. Assuming rates of
GRBs launched in globular cluster found from the redshift distribution of short
burst and adopting the current globular cluster space-density around the solar
system it is found that the expected minimal distance d_min for such a GRB in
the last Gyr is in the range d_min ~ 1 - 3.5 kpc. From the average gamma-ray
luminosity of a short GRB significant depletion of the terrestrial ozone-layer
is expected if such an event explodes at a distance of ~1 kpc. In the last Gyr
a few globular cluster passages are expected within a distance of d_min from
the solar system and a GRB should have exploded during one of these passages.
Globular cluster - solar system encounters and events of mass extinction in the
history of life can be correlated to investigate the impact of a nearby GRB on
the terrestrial biota. To explore such a correlation reliable globular cluster
positions relative to the solar system have to be calculated for the time span
of the fossil record of the last 600 Myr. The upcoming GAIA mission will be
crucial to determine the possible time intervals of the occurrence of nearby
GRBs launched in globular clusters.
View original:
http://arxiv.org/abs/1112.1792
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