The bispectrum of f(R) cosmologies

Journal Article · Tue Nov 01 04:00:00 EDT 2011 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2011/11/019· OSTI ID:22280260

Gil-Marín, Héctor ^[1]; Schmidt, Fabian ^[2]; Hu, Wayne ^[3]; Jimenez, Raul; Verde, Licia ^[4]

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1. Institute of Space Sciences (IEEC-CSIC), Faculty of Science, Campus UAB, Bellaterra 08193 (Spain)
2. Theoretical Astrophysics, California Institute of Technology, Mail Code 350-17, Pasadena, California 91125 (United States)
3. Kavli Institute for Cosmological Physics, Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
4. ICREA Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona (Spain)

In this paper we analyze a suite of cosmological simulations of modified gravitational action f(R) models, where cosmic acceleration is induced by a scalar field that acts as a fifth force on all forms of matter. In particular, we focus on the bispectrum of the dark matter density field on mildly non-linear scales. For models with the same initial power spectrum, the dark matter bispectrum shows significant differences for cases where the final dark matter power spectrum also differs. Given the different dependence on bias of the galaxy power spectrum and bispectrum, bispectrum measurements can close the loophole of galaxy bias hiding differences in the power spectrum. Alternatively, changes in the initial power spectrum can also hide differences. By constructing ΛCDM models with very similar final non-linear power spectra, we show that the differences in the bispectrum are reduced (∼<4%) and are comparable with differences in the imperfectly matched power spectra. These results indicate that the bispectrum depends mainly on the power spectrum and less sensitively on the gravitational signatures of the f(R) model. This weak dependence of the matter bispectrum on gravity makes it useful for breaking degeneracies associated with galaxy bias, even for models beyond general relativity.

• OSTI ID: 22280260
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 11 Vol. 2011; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
COSMOLOGICAL CONSTANT
COSMOLOGY
DENSITY
ENERGY SPECTRA
GALAXIES
GENERAL RELATIVITY THEORY
GRAVITATION
NONLINEAR PROBLEMS
NONLUMINOUS MATTER
SCALAR FIELDS