Disk Regrowth in E/S0 Galaxies and its Environmental Dependence Public Deposited

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  • March 22, 2019
Creator
  • Moffett, Amanda Jean
    • Affiliation: College of Arts and Sciences, Department of Physics and Astronomy
Abstract
  • This work is focused on the investigation of observational evidence for the predicted disk regrowth process, which may allow spheroid-dominated E/S0 galaxies to rebuild spiral disks resembling that of the Milky Way Galaxy. By combining analysis of several complementary galaxy samples, we derive new observational constraints on the frequency, significance, and conditions of E/S0 disk regrowth. We find that UV-detected disks, which represent recent star formation activity, are exceptionally common in low-mass E/S0 galaxies, and we define a new class of UV-Bright (UV-B) disk E/S0s that is associated with significant (>10% by mass) recent disk growth, blue optical outer-disk colors, and enhanced atomic gas content. These UV-B disks are closely linked to a particular class of low-mass, optically blue E/S0s that were previously hypothesized to host active disk regrowth. The detection of UV-B disks around nearly all low-mass, blue E/S0s supports this picture and reinforces the potential importance of mass scales in the disk regrowth process. We also find that another type of mass scale, involving the mass of the group halo in which a galaxy resides, appears to play an important role in disk regrowth. Below a group halo mass of ~10^11.5 Msun, blue E/S0s, gas-dominated galaxies, and UV-B disks all become more common, which may imply that such low group halo mass environments are important for allowing disk regrowth to proceed. This picture is consistent with both the variations of E/S0 and spiral galaxy frequency as a function of environment, with spiral galaxy frequencies rising at low group halo mass, and the observed similarity between typical environments of E/S0 and spiral galaxies at low baryonic mass (<10^10 Msun). Finally, we find direct evidence for secondary stellar disks in the kinematics of 6 out of 24 S0 galaxies for which we can confidently assess the presence or absence of secondary disks, but due to the small number of identifications, we cannot yet draw firm conclusions about any preference for specific mass, environment, or color regimes among such galaxies.
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  • In Copyright
Advisor
  • Kannappan, Sheila
Degree
  • Doctor of Philosophy
Graduation year
  • 2013
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