STELLAR POPULATIONS AND RADIAL MIGRATIONS IN VIRGO DISK GALAXIES

Journal Article · Wed Oct 10 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/758/1/41· OSTI ID:22092098

Roediger, Joel C.; Courteau, Stephane ^[1]; Sanchez-Blazquez, Patricia ^[2]; McDonald, Michael ^[3]

---

1. Department of Physics, Engineering Physics and Astronomy, Queen's University, Kingston, Ontario (Canada)
2. Deptartamento de Fisica Teorica, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)
3. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology Cambridge, MA (United States)

We present new stellar age profiles, derived from well-resolved optical and near-infrared images of 64 Virgo cluster disk galaxies, whose analysis poses a challenge for current disk galaxy formation models. Our ability to break the age-metallicity degeneracy and the significant size of our sample represent key improvements over complementary studies of field disk galaxies. Our results can be summarized as follows: first, and contrary to observations of disk galaxies in the field, these cluster galaxies are distributed almost equally amongst the three main types of disk galaxy luminosity profiles (I/II/III), indicating that the formation and/or survival of Type II breaks is suppressed within the cluster environment. Second, we find examples of statistically significant inversions ({sup U}-shapes{sup )} in the age profiles of all three disk galaxy types, reminiscent of predictions from high-resolution simulations of classically truncated Type II disks in the field. These features characterize the age profiles for only about a third ({<=}36%) of each disk galaxy type in our sample. An even smaller fraction of cluster disks ({approx}11% of the total sample) exhibit age profiles that decrease outward (i.e., negative age gradients). Instead, flat and/or positive age gradients prevail ({>=}50%) within our Type I, II, and III subsamples. These observations thus suggest that while stellar migrations and inside-out growth can play a significant role in the evolution of all disk galaxy types, other factors contributing to the evolution of galaxies can overwhelm the predicted signatures of these processes. We interpret our observations through a scenario whereby Virgo cluster disk galaxies formed initially like their brethren in the field but which, upon falling into the cluster, were transformed into their present state through external processes linked to the environment (e.g., ram-pressure stripping and harassment). Current disk galaxy formation models, which have largely focused on field galaxies, fail to reproduce these results, thus calling for adequate hydrodynamical simulations of dense galaxy environments if we are to understand cluster disks. The current paper highlights numerous constraints for such simulations. In the Appendix, we confirm the claim by Erwin et al. that Type II breaks are absent in Virgo cluster S0s and discuss the detection of Type III breaks in such galaxies.

• OSTI ID: 22092098
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 758; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
GALACTIC EVOLUTION
GALAXIES
GALAXY CLUSTERS
IMAGES
LUMINOSITY
NEAR INFRARED RADIATION
RESOLUTION
VISIBLE RADIATION