Joel C. Roediger, Stephane Courteau, Patricia Sanchez-Blazquez
We present new constraints on disk galaxy formation models based on age and
metallicity profiles derived from well-resolved optical and near-infrared
images of 62 Virgo cluster disk galaxies. One third of our galaxies with light
profile breaks (Type IIs) show age profile inversions, while most galaxies
without such breaks (Type Is) have either flat or rising age profile with
radius. Breaks in disk galaxy luminosity profiles can be attributed to such
fundamental processes as angular momentum conservation and redistribution, star
formation efficiencies, gas flows, feedback, disk heating and more. The
existence of flat and inverted age profiles in Type I and II disks,
respectively, agrees well with recent models involving some of these processes
but no explanation exists for Type I galaxies with positive age gradients. Most
existing data lack the discriminating power to distinguish between the
formation models which predict inverted age profiles in Type II disks.
Interestingly, the presence or absence of age profile inversions is common to
both Type I and II disks, suggesting an intricate mix of formation processes in
these galaxies. No single model of stellar migration, gas accretion or warping
in galaxy disks can account for the diversity of luminosity and stellar
population profiles observed in Type I and II galaxies. In the Appendix, we
confirm the claim by Erwin et al. (2012) that Type II breaks are absent in
Virgo cluster S0s and discuss the nature of upturns in (Type III) disk
luminosity profiles.
View original:
http://arxiv.org/abs/1201.6361
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