A recently quenched isolated dwarf galaxy outside of the Local Group environment

Abstract

We report the serendipitous identification of a low mass ($M_{\ast }\sim 2\times 10^6{\mathrm{M}}_{\odot }$), isolated, likely quenched dwarf galaxy in the "foreground" of the COSMOS-CANDELS field. From deep Hubble Space Telescope (HST) imaging we infer a surface brightness fluctuation distance for COSMOS-dw1 of $D_{\mathrm{SBF}}=22\pm 3$ Mpc, which is consistent with its radial velocity of $cz=1222\pm 64$ km s${}^{-1}$ via Keck/LRIS. At this distance, the galaxy is 1.4 Mpc in projection from its nearest massive neighbor. We do not detect significant H$\alpha$ emission (EW(H$\alpha$)$=-0.4\pm 0.5$ angstroms), suggesting that COSMOS dw1 is likely quenched. Very little is currently known about isolated quenched galaxies in this mass regime. Such galaxies are thought to be rare, as there is no obvious mechanism to permanently stop star formation in them; to date there are only four examples of well-studied quenched field dwarfs, only two of which appear to have quenched in isolation. COSMOS-dw1 is the first example outside of the immediate vicinity of the Local Group. COSMOS-dw1 has a relatively weak D${}_{\mathrm{n}}$4000 break and the HST data show a clump of blue stars indicating that star formation ceased only recently. We speculate that COSMOS-dw1 was quenched due to internal feedback, which was able to temporarily suspend star formation. In this scenario the expectation is that quenched isolated galaxies with masses $M_{\ast }=10^6-10^7$ M${}_{\odot }$ generally have luminosity-weighted ages $\lesssim 1$ Gyr.

8 pages, 4 figures

References in corpus (8)

• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• The ACS Nearby Galaxy Survey Treasury
• Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function
• The Invisibles: A Detection Algorithm to Trace the Faintest Milky Way Satellites
• Cosmicflows-3: Two Distance$-$Velocity Calculators
• The Dragonfly Nearby Galaxies Survey. III. The Luminosity Function of the M101 Group
• Using Surface Brightness Fluctuations to Study Nearby Satellite Galaxy Systems: Calibration and Methodology
• A new isolated dSph galaxy near the Local Group

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