TWO LOCAL VOLUME DWARF GALAXIES DISCOVERED IN 21 cm EMISSION: PISCES A AND B

Journal Article · Thu Jan 01 04:00:00 EST 2015 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/798/1/L21· OSTI ID:22364711

Tollerud, Erik J.; Geha, Marla C. ^[1]; Grcevich, Jana ^[2]; Putman, Mary E. ^[3]; Stern, Daniel ^[4]

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1. Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 06510 (United States)
2. Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States)
3. Department of Astronomy, Columbia University, New York, NY 10027 (United States)
4. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States)

We report the discovery of two dwarf galaxies, Pisces A and B, from a blind 21 cm H I search. These were the only two galaxies found via optical imaging and spectroscopy of 22 H I clouds identified in the GALFA-H I survey as dwarf galaxy candidates. They have properties consistent with being in the Local Volume (<10 Mpc), and one has resolved stellar populations such that it may be on the outer edge of the Local Group (∼1 Mpc from M31). While the distance uncertainty makes interpretation ambiguous, these may be among the faintest star-forming galaxies known. Additionally, rough estimates comparing these galaxies to ΛCDM dark matter simulations suggest consistency in number density, implying that the dark matter halos likely to host these galaxies are primarily H I-rich. The galaxies may thus be indicative of a large population of dwarfs at the limit of detectability that are comparable to the faint satellites of the Local Group. Because they are outside the influence of a large dark matter halo to alter their evolution, these galaxies can provide critical anchors to dwarf galaxy formation models.

• OSTI ID: 22364711
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 798; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CLOUDS
COMPARATIVE EVALUATIONS
COSMOLOGICAL CONSTANT
COSMOLOGY
DENSITY
DISTANCE
GALACTIC EVOLUTION
GALAXIES
HYDROGEN
NONLUMINOUS MATTER
SATELLITES
STAR EVOLUTION
STARS