Galaxy formation in WMAP1 and WMAP7 cosmologies

Guo, Qi, White, Simon, Angulo, Raul E, Henriques, Bruno, Lemson, Gerard, Boylan-Kolchin, Michael, Thomas, Peter and Short, Chris (2013) Galaxy formation in WMAP1 and WMAP7 cosmologies. Monthly Notices of the Royal Astronomical Society, 428 (2). pp. 1351-1365. ISSN 0035-8711

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Using the technique of Angulo & White (2010) we scale the Millennium and Millennium-II simulations of structure growth in a LCDM universe from the cosmological parameters with which they were carried out (based on first-year results from the Wilkinson Microwave Anisotropy Probe, WMAP1) to parameters consistent with the seven-year WMAP data (WMAP7). We implement semi-analytic galaxy formation modelling on both simulations in both cosmologies to investigate how the formation, evolution and clustering of galaxies are predicted to vary with cosmological parameters. The increased matter density Omega_m and decreased linear fluctuation amplitude sigma8 in WMAP7 have compensating effects, so that the abundance and clustering of dark halos are predicted to be very similar to those in WMAP1 for z <= 3. As a result, local galaxy properties can be reproduced equally well in the two cosmologies by slightly altering galaxy formation parameters. The evolution of the galaxy populations is then also similar. In WMAP7, structure forms slightly later. This shifts the peak in cosmic star formation rate to lower redshift, resulting in slightly bluer galaxies at z=0. Nevertheless, the model still predicts more passive low-mass galaxies than are observed. For rp< 1Mpc, the z=0 clustering of low-mass galaxies is weaker for WMAP7 than for WMAP1 and closer to that observed, but the two cosmologies give very similar results for more massive galaxies and on large scales. At z>1 galaxies are predicted to be more strongly clustered for WMAP7. Differences in galaxy properties, including, clustering, in these two cosmologies are rather small up to redshift 3. Given the considerable residual uncertainties in galaxy formation models, it is difficult to distinguish between WMAP1 and WMAP7 on the basis of current galaxy surveys.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: Peter Thomas
Date Deposited: 04 Feb 2013 15:58
Last Modified: 03 Jul 2019 00:17

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