| Abstrakt: |
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 < VLSR < +650 km s−1, for neutral hydrogen sources. We are able to probe regions of the sky at lower Galactic latitudes and smaller 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. [ABSTRACT FROM AUTHOR] |
