Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2012-01-30
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
35 pages, 7 figures. Submitted to ApJ. Comments welcome. Full resolution version available at http://www.astro.queensu.ca/~c
Scientific paper
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.
Courteau Stephane
Roediger Joel C.
Sanchez-Blazquez Patricia
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