期刊
PHYSICAL REVIEW D
卷 85, 期 2, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevD.85.023504
关键词
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资金
- Gordon and Betty Moore Foundation at Caltech
- U.S. National Science Foundation [AST-0807337]
- U.S. Department of Energy [DE-FG03-02-ER40701]
- David and Lucile Packard Foundation
Several recent studies have shown how to properly calculate the observed clustering of galaxies in a relativistic context, and uncovered corrections to the Newtonian calculation that become significant on scales near the horizon. Here, we retrace these calculations and show that, on scales approaching the horizon, the observed galaxy power spectrum depends strongly on which gauge is assumed to relate the intrinsic fluctuations in galaxy density to matter perturbations through a linear bias relation. Starting from simple physical assumptions, we derive a gauge-invariant expression relating galaxy density perturbations to matter density perturbations on large scales, and show that it reduces to a linear bias relation in a synchronous-comoving gauge, corroborating an assumption made in several recent papers. We evaluate the resulting observed galaxy power spectrum, and show that it leads to corrections similar to an effective non-Gaussian bias corresponding to a local f(NL,eff) less than or similar to 0.5. This number can serve as a guideline as to which surveys need to take into account relativistic effects. We also discuss the scale-dependent bias induced by primordial non-Gaussianity in the relativistic context, which again is simplest in a synchronous-comoving gauge.
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