An explanation for the observed weak size evolution of disk galaxies

Rachel S. Somerville*, Marco Barden, Hans Walter Rix, Eric F. Bell, Steven V.W. Beckwith, Andrea Borch, John A.R. Caldwell, Boris Häußler, Catherine Heymans, Knud Jahnke, Shardha Jogee, Daniel H. McIntosh, Klaus Meisenheimer, Chien Y. Peng, Sebastian F. Sánchez, Lutz Wisotzki, Christian Wolf

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

145 Citations (Scopus)

Abstract

Surveys of distant galaxies with the Hubble Space Telescope and from the ground have shown that there is only mild evolution in the relationship between radial size and stellar mass for galactic disks from z ∼ 1 to the present day. Using a sample of nearby disk-dominated galaxies from the Sloan Digital Sky Survey (SDSS) and high-redshift data from the GEMS (Galaxy Evolution from Morphology and SEDs) survey, we investigate whether this result is consistent with theoretical expectations within the hierarchical paradigm of structure formation. The relationship between virial radius and mass for dark matter halos in the ΔCDM model evolves by about a factor of 2 over this interval. However, N-body simulations have shown that halos of a given mass have less centrally concentrated mass profiles at high redshift. When we compute the expected disk size-stellar mass distribution, accounting for this evolution in the internal structure of dark matter halos and the adiabatic contraction of the dark matter by the self-gravity of the collapsing baryons, we find that the predicted evolution in the mean size at fixed stellar mass since z ∼ 1 is about 15%-20%, in good agreement with the observational constraints from GEMS. At redshift z ∼ 2, the model predicts that disks at fixed stellar mass were on average only 60% as large as they are today. Similarly, we predict that the rotation velocity at a given stellar mass (essentially the zero point of the Tully-Fisher relation) is only about 10% larger at z ∼ 1 (20% at z ∼ 2) than at the present day.

Original languageEnglish
Pages (from-to)776-786
Number of pages11
JournalAstrophysical Journal
Volume672
Issue number2
DOIs
Publication statusPublished - 10 Jan 2008
Externally publishedYes

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