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The Theoretical Institute for Advanced Research in Astrophysics (TIARA)

Theoretical modeling of large-scale galaxy distribution for a test of cosmic acceleration
Image Credit: Okumura et al
Theoretical modeling of large-scale galaxy distribution for a test of cosmic acceleration
The black solid line is the quadrupole moment of the galaxy power spectrum (the suppression of the power on small scales is due to virial motions of satellite galaxies) and the blue line is the reconstructed halo power spectrum after our method is applied.
Revealing the acceleration of the cosmic expansion, known as dark energy, is one of the most important issues in cosmology. To investigate the origin of the acceleration, observation of large-scale structures of the universe through galaxy redshift surveys is considered as the most powerful probe. In the galaxy clustering analysis, one of the difficulties to model the power spectrum or correlation function of galaxies arises from the non-trivial relationship between dark matter halos and galaxies, especially due to the presence of satellite galaxies because they have large velocity dispersions. In Okumura et al (2017), we developed a theoretical formalism to recover the power spectrum of halos from the observed galaxy distribution by minimizing the contamination of satellite galaxies, and tested it to the “observed” galaxy distribution in simulations. In the figure below, the black solid line is the quadrupole moment of the galaxy power spectrum (the suppression of the power on small scales is due to virial motions of satellite galaxies) and the blue line is the reconstructed halo power spectrum after our method is applied. It is in excellent agreement with the true halo power spectrum directly measured from the simulations (red points) to within 5 per cent over all the wave number range. Hence, our method enables to maximally extract the information of the cosmic acceleration from the observed galaxy distribution.
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