Max Tegmark's cosmology library: bursts
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THE ANGULAR POWER SPECTRUM OF BATSE 3B GAMMA-RAY BURSTS
Authors:
Max Tegmark,
Dieter H. Hartmann,
Michael S. Briggs & Charles A. Meegan
Abstract:
We compute the angular power spectrum C_l from the
BATSE 3B catalog
of 1122
gamma-ray bursts, and find no evidence for clustering on any scale.
These constraints bridge the entire range from small scales
(which probe source clustering and burst repetition)
to the largest scales (which constrain possible anisotropies from the
Galactic halo
or from nearby cosmological large scale structures).
We develop an analysis technique that takes the
angular position errors into account,
which enables us to place tight upper limits on
the clustering down to scales l\approx 60,
corresponding to a few degrees on the sky.
The minimum-variance burst weighting that we employ is
graphically visualized as an all-sky map where each burst is smeared out
by an amount corresponding to its position uncertainty.
We also present separate band-pass filtered sky maps for the quadrupole
term
and for the multipole-ranges l=3-10 and l=11-30, so that
the fluctuations on different angular scales can be separately
inspected for visual features such as localized
``hot spots" or structures aligned with the Galactic plane.
These filtered maps reveal no apparent deviations from isotropy.
Online references:
This site also contains the latest versions of a paper that is referenced in
the text;
Tegmark 1995.
You can find many of the referenced papers from the BATSE team
here.
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This page was last modified July 1, 1998.
max@ias.edu
