Journal Article

Mock galaxy redshift catalogues from simulations: implications for Pan-STARRS1

Yan-Chuan Cai, Raul E. Angulo, Carlton M. Baugh, Shaun Cole, Carlos S. Frenk and Adrian Jenkins

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 395, issue 3, pages 1185-1203
Published in print May 2009 | ISSN: 0035-8711
Published online May 2009 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2009.14402.x
Mock galaxy redshift catalogues from simulations: implications for Pan-STARRS1

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We describe a method for constructing mock galaxy catalogues which are well suited for use in conjunction with large photometric surveys. We use the semi-analytic galaxy formation model of Bower et al. implemented in the Millennium N-body simulation of the evolution of dark matter clustering in a Λ cold dark matter cosmology. We apply our method to the specific case of the surveys soon to commence with PS1, the first of four telescopes planned for the Pan-STARRS. PS1 has five photometric bands, g, r, i, z and y and will carry out an all-sky ‘3π’ survey and a medium deep survey (MDS) over 84 deg2. We calculate the expected magnitude limits for extended sources in the two surveys. We find that, after 3 year, the 3π survey will have detected over 108 galaxies in all five bands, 10 million of which will lie at redshift z > 0.9, while the MDS will have detected over 107 galaxies with 0.5 million lying at z > 2. These numbers at least double if the detection in the shallowest band, y, is not required. We then evaluate the accuracy of photometric redshifts estimated using an off-the-shelf photo-z code. With the grizy bands alone, it is possible to achieve an accuracy in the 3π survey of Δz/(1 +z) ∼ 0.06 in the range 0.25 < z < 0.8, which could be reduced by about 15 per cent using near-infrared photometry from the Infrared Deep Sky Survey (UKIDDS) survey, but would increase by about 25 per cent for the deeper sample without the y-band photometry. For the MDS, an accuracy of Δz/(1 +z) ∼ 0.05 is achievable for 0.02 < z < 1.5 using grizy. A dramatic improvement in accuracy is possible by selecting only red galaxies. In this case, Δz/(1 +z) ∼ 0.02–0.04 is achievable for ∼100 million galaxies at 0.4 < z < 1.1 in the 3π survey and for 30 million galaxies in the MDS at 0.4 < z < 2. We investigate the effect of using photometric redshifts in the estimate of the baryonic acoustic oscillation scale. We find that PS1 will achieve a similar accuracy in this estimate as a spectroscopic survey of 20 million galaxies.

Keywords: cosmological parameters; cosmology: large-scale structure of Universe

Journal Article.  12447 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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