Smallangle CMB temperature anisotropies induced by cosmic strings
Abstract
We use NambuGoto numerical simulations to compute the cosmic microwave background (CMB) temperature anisotropies induced at arcminute angular scales by a network of cosmic strings in a FriedmannLemaîtreRobertsonWalker (FLRW) expanding universe. We generate 84 statistically independent maps on a 7.2° field of view, which we use to derive basic statistical estimators such as the onepoint distribution and twopoint correlation functions. At high multipoles, the mean angular power spectrum of stringinduced CMB temperature anisotropies can be described by a power law slowly decaying as ℓ^{p}, with p=0.889 (+0.001,0.090) (including only systematic errors). Such a behavior suggests that a nonvanishing string contribution to the overall CMB anisotropies may become the dominant source of fluctuations at small angular scales. We therefore discuss how well the temperature gradient magnitude operator can trace strings in the context of a typical arcminute diffractionlimited experiment. Including both the thermal and nonlinear kinetic SunyaevZel’dovich effects, the OstrikerVishniac effect, and the currently favored adiabatic primary anisotropies, we find that, on such a map, strings should be “eye visible,” with at least of order ten distinctive string features observable on a 7.2° gradient map, for tensions U down to GU≃2×10^{7} (in Planck units). This suggests that, with upcoming experiments such as the Atacama Cosmology Telescope (ACT), optimal nonGaussian, stringdevoted statistical estimators applied to smallangle CMB temperature or gradient maps may put stringent constraints on a possible cosmic string contribution to the CMB anisotropies.
 Publication:

Physical Review D
 Pub Date:
 August 2008
 DOI:
 10.1103/PhysRevD.78.043535
 arXiv:
 arXiv:0708.1162
 Bibcode:
 2008PhRvD..78d3535F
 Keywords:

 98.80.Cq;
 98.70.Vc;
 Particletheory and fieldtheory models of the early Universe;
 Background radiations;
 Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 17 pages, 9 figures. v2: matches published version, minor clarifications added, typo in Eq. (8) fixed, results unchanged