A Correlated Search for Local Dwarf Galaxies in GALFA-HI and Pan-STARRS. (arXiv:1906.05287v1 [astro-ph.GA])

A Correlated Search for Local Dwarf Galaxies in GALFA-HI and Pan-STARRS. (arXiv:1906.05287v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+DeFelippis_D/0/1/0/all/0/1">Daniel DeFelippis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Putman_M/0/1/0/all/0/1">Mary Putman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tollerud_E/0/1/0/all/0/1">Erik Tollerud</a>

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 HI (GALFA-HI) survey, a radio survey which covers one-third of the sky at
velocities $-650 < V_{rm{LSR}} < +650 ; rm{km} ; rm{s^{-1}}$, 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 (SoFiA) on GALFA-HI 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 ($b=-8^{circ}$) that is comparable in velocity width and HI-flux to other recently discovered local volume galaxies. We find we are sensitive to Leo T-like objects out to $1 ; rm{Mpc}$ at velocities clear from background HI 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 $500 ; rm{kpc}$ of the Milky Way in the one-third of the sky covered by the GALFA-HI footprint and discuss our nondetection in a cosmological context.

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 HI (GALFA-HI) survey, a radio survey which covers one-third of the sky at
velocities $-650 < V_{rm{LSR}} < +650 ; rm{km} ; rm{s^{-1}}$, 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 (SoFiA) on GALFA-HI 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 ($b=-8^{circ}$) that is comparable in velocity
width and HI-flux to other recently discovered local volume galaxies. We find
we are sensitive to Leo T-like objects out to $1 ; rm{Mpc}$ at velocities
clear from background HI 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
$500 ; rm{kpc}$ of the Milky Way in the one-third of the sky covered by the
GALFA-HI footprint and discuss our nondetection in a cosmological context.

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