Spherical harmonic expansion of gamma-ray burst distributions: Probing large-scale structure?

Tsvi Piran*, Anupam Singh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

We have laid down the formalism and techniques necessary for computing the multipole components in a spherical harmonic expansion for bursting sources given any specific power spectrum of density perturbations. Using this formalism we have explicitly computed and tabulated the expected first few multipole components for the γ-ray burst (GRB) distribution using a cold dark matter power spectrum. Unfortunately, our analysis leads us to expect that an anisotropy signal for this model of structure formation will be below the shot-noise level for the foreseeable future. Earlier studies by others had claimed that it may be possible within a decade or so to probe structure formation using the angular distribution of GRBs. We find that while it may be possible to probe the dipole due to our motion with respect to the cosmic rest frame, it does not seem feasible to probe the multipole components due to intrinsic fluctuations if the actual power spectrum is fixed to within an order of magnitude by the cold dark matter model of structure formation.

Original languageEnglish
Pages (from-to)552-559
Number of pages8
JournalAstrophysical Journal
Volume483
Issue number2 PART I
DOIs
StatePublished - 1997

Keywords

  • Cosmology: theory
  • Gamma rays: bursts
  • Large-scale structure of universe

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