A tidally disrupting dwarf galaxy in the halo of NGC 253

Abstract

We report the discovery of Scl-MM-Dw2, a new dwarf galaxy at a projected separation of $\sim$50 kpc from NGC 253, as part of the PISCeS (Panoramic Imaging Survey of Centaurus and Sculptor) project. We measure a tip of the red giant branch distance of $3.12\pm 0.30$ Mpc, suggesting that Scl-MM-Dw2 is likely a satellite of NGC 253. We qualitatively compare the distribution of red giant branch (RGB) stars in the color-magnitude diagram with theoretical isochrones and find that it is consistent with an old, $\sim$12 Gyr, and metal poor, $-2.3<$[Fe/H]$<-1.1$, stellar population. We also detect a small number of asymptotic giant branch stars consistent with a metal poor $2-3$ Gyr population in the center of the dwarf. Our non-detection of HI in a deep Green Bank Telescope spectrum implies a gas fraction $M_{HI}/L_V<0.02$ Msun/Lsun. The stellar and gaseous properties of Scl-MM-Dw2 suggest that it is a dwarf spheroidal galaxy. Scl-MM-Dw2 has a luminosity of $M_V=-12.1\pm 0.5$ mag and a half-light radius of $r_h=2.94\pm 0.46$ kpc which makes it moderately larger than dwarf galaxies in the Local Group of the same luminosity. However, Scl-MM-Dw2 is very elongated ($\epsilon =0.66\pm 0.06$) and it has an extremely low surface brightness (${\mu }_{0,V}=26.5\pm 0.7$ mag arcsec${}^{-2}$). Its elongation and diffuseness make it an outlier in the ellipticity-luminosity and surface brightness-luminosity scaling relations. These properties suggest that this dwarf is being tidally disrupted by NGC 253.

6 pages, 4 figures, 1 table. ApJL accepted

References in corpus (14)

• Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster
• Tracing Galaxy Formation with Stellar Halos II: Relating Substructure in Phase- and Abundance-Space to Accretion Histories
• The ACS Nearby Galaxy Survey Treasury IX. Constraining asymptotic giant branch evolution with old metal-poor galaxies
• Hydra II: a faint and compact Milky Way dwarf galaxy found in the Survey of the Magellanic Stellar History
• The Dearth of Neutral Hydrogen in Galactic Dwarf Spheroidal Galaxies
• A New Faint Milky Way Satellite Discovered in the Pan-STARRS1 3 pi Survey
• Discovery of New Dwarf Galaxies in the M81 Group
• The discovery of seven extremely low surface brightness galaxies in the field of the nearby spiral galaxy M101
• A Hero's Dark Horse: Discovery of an Ultra-Faint Milky Way Satellite in Pegasus
• The Star Formation History and Extended Structure of the Hercules Milky Way Satellite
• Discovery of a close pair of faint dwarf galaxies in the halo of Centaurus A
• Discovery of a new faint dwarf galaxy associated with NGC 253
• A Suprime-Cam study of the stellar population of Ursa Major I dwarf spheroidal galaxy
• The intrinsic ellipticity of dwarf spheroidal galaxies: constraints from the Andromeda system

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