arXiv subjects

B. Allen

Publications and source records attributed to B. Allen.

166 records · Page 10Linked to original sources

arXiv1998

Cosmic-String-Seeded Structure Formation

We describe the results of high-resolution numerical simulations of string-induced structure formation in open universes and those with a non-zero cosmological constant. For models with $Γ= Ωh = 0.1 - 0.2$ and a cold dark matter background, we show that the linear density fluctuation power spectrum has both an amplitude at $8 h^{-1} Mpc, σ_8$, and an overall shape which are consistent within uncertainties with those currently inferred from galaxy surveys. The cosmic string scenario with hot dark matter requires a strongly scale-dependent bias in order to agree with observations.

astro-ph↗

arXiv1997

CMB Anisotropy Induced by Cosmic Strings on Angular Scales $>~ 15'$

We have computed an estimate of the angular power spectrum of the Cosmic Microwave Background (CMB) induced by cosmic strings on angular scales $>~ 15'$, using a numerical simulation of a cosmic string network; and decomposed this pattern into scalar, vector, and tensor parts. We find no evidence for strong acoustic oscillations in the scalar anisotropy but rather a broad peak. The anisotropies from vector modes dominate except on very small angular scales while the tensor anisotropies are sub-dominant on all angular scales. The anisotropies generated after recombination are even more important than in adiabatic models. We expect that these qualitative features are robust to the varying of cosmological parameters, a study which has not yet been done.

astro-ph↗

arXiv1996

Large Angular Scale CMB Anisotropy Induced by Cosmic Strings

We simulate the anisotropy in the cosmic microwave background (CMB) induced by cosmic strings. By numerically evolving a network of cosmic strings we generate full-sky CMB temperature anisotropy maps. Based on $192$ maps, we compute the anisotropy power spectrum for multipole moments $\ell \le 20$. By comparing with the observed temperature anisotropy, we set the normalization for the cosmic string mass-per-unit-length $μ$, obtaining $Gμ/c^2=1.05 {}^{+0.35}_{-0.20} \times10^{-6}$, which is consistent with all other observational constraints on cosmic strings. We demonstrate that the anisotropy pattern is consistent with a Gaussian random field on large angular scales.

astro-ph↗

arXiv1994

Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic Strings

We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of $Z = 100$ to the present and calculated the anisotropies which they induce. Based on a limited number of realizations, we have compared the results of our simulations with the observations of the COBE-DMR experiment. We have obtained a preliminary estimate of the string mass-per-unit-length $μ$ in the cosmic string scenario.

astro-ph↗