Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Three Ultra-faint Dwarf Galaxies

Burçin Mutlu-Pakdil, David J. Sand, Denija Crnojević, Michael G. Jones, Nelson Caldwell, Puragra Guhathakurta, Anil C. Seth, Joshua D. Simon, Kristine Spekkens, Jay Strader, Elisa Toloba

Research output: Contribution to journalArticlepeer-review

Abstract

We present deep Hubble Space Telescope (HST) imaging of five faint dwarf galaxies associated with the nearby spiral NGC 253 (D ≈ 3.5 Mpc). Three of these are newly discovered dwarf galaxies, while all five were found in the Panoramic Imaging Survey of Centaurus and Sculptor, a Magellan+Megacam survey to identify faint dwarfs and other substructures in resolved stellar light around massive galaxies outside of the Local Group. Our HST data reach ≲3 magnitudes below the tip of the red giant branch for each dwarf, allowing us to derive their distances, structural parameters, and luminosities. All five systems contain mostly old, metal-poor stellar populations (age ∼ 12 Gyr, [M/H] ≳ -1.5) and have sizes (r h ∼110-3000 pc) and luminosities (M V ∼-7 to -12 mag) largely consistent with Local Group dwarfs. The three new NGC 253 satellites are among the faintest systems discovered beyond the Local Group. We also use archival H i data to place limits on the gas content of our discoveries. Deep imaging surveys such as our program around NGC 253 promise to elucidate the faint end of the satellite luminosity function and its scatter across a range of galaxy masses, morphologies, and environments in the decade to come.

Original languageEnglish (US)
Article number77
JournalAstrophysical Journal
Volume926
Issue number1
DOIs
StatePublished - Feb 1 2022
Externally publishedYes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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