20-24 March 2023
Haus H, Telegrafenberg
Europe/Berlin timezone

Census of Northern Local Group Dwarf Galaxies using UNIONS

22 Mar 2023, 10:37
Haus H, Telegrafenberg

Haus H, Telegrafenberg

Potsdam, Germany
Poster SESSION 3 : Dwarf galaxies: dwarf spheroidal, ultra-faint dwarfs, dwarf irregulars SESSION 3 : Dwarf galaxies: dwarf spheroidal, ultra-faint dwarfs, dwarf irregulars


Simon Smith (University of Victoria)


Dwarf galaxies play a key role in probing the dynamics of the Milky Way, the history of star formation in the Local Group, and the accretion and retention of gas in dark matter halos at the smallest scales of galaxy formation. In this work, we use the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS), the deepest, widest photometric survey ever carried out in the northern hemisphere, to complete a systematic analysis of 3600 sq. deg. of sky in search of new dwarf galaxies within 1 Mpc of the Milky Way. This search aims to detect Milky Way satellites, M31 satellites, and nearby, isolated dwarf galaxies using a matched-filter algorithm. To date, all previously known dwarf galaxies in the survey footprint have been recovered, each with high statistical significance. We present the discovery of a new Milky Way dwarf galaxy candidate, a new, faint star cluster, and report on the follow-up of numerous high confidence candidate detections. The end goal of this work will be to assess the completeness of the Milky Way satellite population as a function of position, luminosity, mass, and size. UNIONS imaging, when completed, is the approximate depth of the LSST after a year of operation, and our studies of the northern hemisphere provide a complementary approach and foretaste of what will come in the era of Rubin.

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Primary author

Simon Smith (University of Victoria)

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