Cosmic Mach Number: a sensitive probe for the growth of structure

M. Yin-Zhe, J. Ostriker, Gong-Bo Zhao

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In this Letter, we investigate the potential power of the Cosmic Mach Number (CMN), which is the ratio between the mean velocity and the velocity dispersion of galaxies as a function of cosmic scales, to constrain cosmologies. We first measure the CMN from 5 catalogues of galaxy peculiar velocity surveys at low redshift (z∈[0.002,0.03]), and use them to contrast cosmological models. Overall, current data is consistent with the WMAP7 ΛCDM model. We find that the CMN is highly sensitive to the growth of structure on scales k∈[0.01,0.1] h/Mpc in Fourier space. Therefore, modified gravity models, and models with massive neutrinos, in which the structure growth generically deviates from that of the ΛCDM model in a scale-dependent way, can be well differentiated from the ΛCDM model by using future CMN data.
Original languageEnglish
Pages (from-to)026
Number of pages1
JournalJournal of Cosmology and Astroparticle Physics
Issue number6
Publication statusPublished - Jun 2012


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