Astronomy and Astrophysics – Astronomy
Scientific paper
Jun 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011mnras.414..209w&link_type=abstract
Monthly Notices of the Royal Astronomical Society, Volume 414, Issue 1, pp. 209-217.
Astronomy and Astrophysics
Astronomy
3
Gamma-Ray Burst: General, Quasars: Absorption Lines, Cosmology: Theory
Scientific paper
Gamma-ray burst (GRB) afterglows offer a probe of the intergalactic medium (IGM) out to high redshift which complements observations along more abundant quasar lines of sight. Although both quasars and GRB afterglows should provide a priori random sightlines through the intervening IGM, it has been observed that strong Mg II absorbers are twice as likely to be found along sightlines towards GRBs. In this paper we study the effect of gravitational lensing by galaxies and their surrounding mass distributions on the statistics of Mg II absorption. We find that the multiband magnification bias could be very strong in the spectroscopic GRB afterglow population and that gravitational lensing is able to explain the discrepancy in density of absorbers, for plausibly steep luminosity functions. The model makes the prediction that to explain the Mg II absorber excess, approximately 20-60 per cent of the spectroscopic afterglow sample (i.e. ˜5-15 of 26 sources) would need to have been multiply imaged, implying that many of these GRBs were repeating bursts. We show that despite this large lensing fraction it is likely that no repeating bursts would yet have been identified by chance owing to the finite sky coverage of GRB searches, while the required multiple image fraction is currently not ruled out by direct observations of the host galaxies. A confirmation of the lensing hypothesis would allow the GRB luminosity function to be constrained down to otherwise inaccessibly faint levels, with potential consequences for GRB models. On the other hand, should multiple images be shown to be absent among the spectroscopic afterglow sample, then gravitational lensing by galaxies will be ruled out as an explanation for the observed Mg II absorber excess.
Oh Siang Peng
Pindor Bartosz
Wyithe Stuart J. B.
No associations
LandOfFree
A possible gravitational lensing explanation for the excess of strong Mg II absorbers in gamma-ray burst afterglow spectra 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 A possible gravitational lensing explanation for the excess of strong Mg II absorbers in gamma-ray burst afterglow spectra, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A possible gravitational lensing explanation for the excess of strong Mg II absorbers in gamma-ray burst afterglow spectra will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-922481