Dwarf galaxies may form in the tidal tails of galaxy interactions. If these tidal dwarf galaxies (TDGs) detach from their parent galaxies, then an independent dwarf galaxy emerges. However, the lifespan of such objects is uncertain. Using IR, UV, and optical images, we conducted a search for detached TDGs from a set of 40 interacting galaxy pairs in the local Universe, and a control sample of 37 spiral galaxies. Both samples include 3.6 micron, 4.5 micron, 8 micron, and NUV images. In an earlier study (Smith et al. 2016), we used the IRAF daofind software (Stetson 1987) to search for star-forming regions within the main bodies of these galaxies and in their extended tidal tails. In the current study, we used the same procedure to search for such regions outside of the galaxies. We used two spatial scales to search for the TDGs, 1 kiloparsec and 2.5 kiloparsecs radius, and then used Spitzer infrared colors to identify and eliminate possible foreground stars and background quasars. The remaining objects may be detached tidal dwarfs that formed in the tails and then escaped. After comparing our observational results of the number of TDGs surrounding our interacting galaxies to the numbers around normal spirals, we find no significant difference in the number of candidate TDGs near interacting galaxy pairs compared to normal spiral galaxies. The most promising TDG candidates will be targeted by follow-up spectroscopic observations to determine their redshifts, metallicities, and their velocity structures. Younger TDGs are expected to have higher metallicities relative to their masses compared to primordial dwarf galaxies, relative to the standard mass-luminosity relationship for galaxies. Furthermore, TDGs should lack dark matter in contrast to primordial dwarf galaxies.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:asrf-1312 |
| Date | 12 April 2019 |
| Creators | Jones, Mark, Smith, Beverly J, Giroux, Mark |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | Appalachian Student Research Forum |
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