Using Surface Brightness Fluctuations to Study Nearby Satellite Galaxy Systems: the Complete Satellite System of M101

Abstract

We use surface brightness fluctuation (SBF) measurements to constrain the distance to low surface brightness (LSB) dwarfs in the vicinity of M101. Recent work has discovered many LSB candidate satellite companions of M101. However, without accurate distances, it is problematic to identify these dwarfs as physical satellites of M101. We use CFHT Legacy Survey (CFHTLS) data to measure the SBF signal for 43 candidate dwarfs. The data is deep enough that we constrain 29 of these to be unassociated background galaxies by their lack of SBF. We measure high S/N SBF signals for two of the candidate dwarfs, which are consistent with being at the distance of M101. The remaining candidates are too LSB and/or small for their distances to be constrained. Still, by comparison with Local Group dwarfs, we argue that the M101 satellite system is likely now complete down to stellar masses of $\sim 5\times 10^5$ M${}_{\odot }$. We also provide a new SBF distance for the nearby dwarf UGC 8882, which suggests that it is significantly outside of the virial radius of M101 and is thus not a physical satellite. By constraining the distances to a majority of the candidates using only archival data, our work demonstrates the usefulness of SBF for nearby LSB galaxies and for studying the satellite systems of nearby massive galaxies.

Submitted to ApJL, comments welcome!

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Cited by in corpus (5)

• Introducing the LBT Imaging of Galactic Halos and Tidal Structures (LIGHTS) survey. A preview of the low surface brightness Universe to be unveiled by LSST
• Using Surface Brightness Fluctuations to Study Nearby Satellite Galaxy Systems: Calibration and Methodology
• A correlation between the number of satellites and the baryonic bulge-to-total ratio extending beyond the Local Group
• Dwarf Galaxy Discoveries from the KMTNet Supernova Program II. The NGC 3585 Group and Its Dynamical State
• A Rich Satellite Population of the NGC 4437 Group and Implications of a Magnitude Gap for Galaxy Group Assembly History