Daily Image
07-08-2019
HI imaging of candidate Local Group dwarf galaxies
| Submitter: | Lilly Bralts-Kelly |
| Description: | Cosmological simulations predict the existence of more low-mass dark matter halos than there are observed dwarf galaxies. This discrepancy is generally attributed to the effects of star formation feedback and reionization, which result in dark matter halos not hosting observable galaxies. We seek to better understand the specifics of these effects as they relate to low-mass galaxy evolution. To do so, we require a population of low-mass galaxies near enough to be detected, but distant enough to avoid modification of their intrinsic properties from interaction with the Milky Way. The ALFALFA survey of the neutral hydrogen (HI) in the local universe yields a small population of ultra-compact high-velocity clouds (UCHVCs), or isolated HI clouds, that may in fact prove to be dwarf galaxies themselves. These sources are classified as UCHVCs according to several criteria, including angular size on the sky, velocity with respect to the local standard of rest, and lack of an optical counterpart in large surveys like the Sloan Digital Sky Survey. In order to investigate this population, we conduct deep VLA/D observations of the HI in several UCHVCs. All of these sources have potential optical counterparts, identified by the pODI instrument on the WIYN 3.5m telescope, and are therefore promising candidate galaxies. Using our deep HI images, we apply the modeling software 3D-Barolo to derive rotation curves for each source, a crucial first step leading to future work on their dark matter content. Although the summer has come to a close, work continues on this project. We intend to investigate the star formation properties of these systems by deriving peak HI column densities and comparing our new HI images to their WIYN/pODI stellar counterparts. We will also use 3D-Barolo to constrain the inclination angle of each source, which will then allow us to derive dynamical masses and address the nature of the dark matter halos of these galaxies. |
| Copyright: | Lilly Bralts-Kelly, Betsey Adams |
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