A Correlated Search for Local Dwarf Galaxies in GALFA-H I and Pan-STARRS
Abstract
In recent years, ultrafaint dwarf (UFD) galaxies have been found through systematic searches of large optical surveys. However, the existence of Leo T, a nearby gas-rich dwarf, suggests that there could be other nearby UFDs that are optically obscured but have gas detectable at nonoptical wavelengths. With this in mind, we perform a search of the full Galactic Arecibo L-band Feed Array H I (GALFA-H I) survey, a radio survey that covers one-third of the sky at velocities -650 < V LSR < +650 km s-1, for neutral hydrogen sources. We are able to probe regions of the sky at lower Galactic latitudes and smaller | {V}{LSR}| compared to previous explorations. We use the Source Finding Application on GALFA-H I and select all sources with similar properties to Leo T and other local dwarf galaxies. We find 690 dwarf galaxy candidates, one of which is particularly promising and likely a new galaxy near the Galactic plane (b = -8°) that is comparable in velocity width and H I-flux to other recently discovered local volume galaxies. We find we are sensitive to Leo T-like objects out to 1 Mpc at velocities clear from background H I emission. We check each candidate’s corresponding optical fields from Pan-STARRS and fit stars drawn from isochrones, but find no evidence of stellar populations. We thus find no other Leo T-like dwarfs within 500 kpc of the Milky Way in the one-third of the sky covered by the GALFA-H I footprint, and discuss our nondetection in a cosmological context.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2019
- DOI:
- 10.3847/1538-4357/ab1e57
- arXiv:
- arXiv:1906.05287
- Bibcode:
- 2019ApJ...879...22D
- Keywords:
-
- galaxies: dwarf;
- Local Group;
- radio lines: ISM;
- surveys;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted to ApJ. 14 pages, 10 figures. Table 2 is available in its entirety as an ancillary file on this page