The M101 Luminosity Function and and the Halo to Halo Scatter Among Local Volume Hosts
Abstract
The Lambda Cold Dark Matter model for structure formation has been very successful at reproducing observations of large scale structures; however challenges emerge at sub-galactic scales. Observations of the faint end of galaxy satellite Luminosity Functions (LFs) are important in reconciling the differences at these smaller scales. This is crucial to constrain the physics governing galaxy formation and evolution, and will also help us to understand the relation between the stellar content and dark matter halo in dwarf galaxies. As part of a semi-automated survey for low surface brightness galaxies in the Canada-France-Hawaíi-Telescope legacy survey, we have examined the M101 group in detail discovering 37 new diffuse dwarf candidates in the vicinity of M101. Examination of 19 of these dwarfs with the Hubble Space Telescope has allowed us to extend the satellite LF of M101 down to MV = -8.2 and compare it to other Local Volume hosts. This shows M101 is extremely sparse with only 8 satellites down to this magnitude, as compared to 26 for M31 and 23.5±7.7 for the median host in the Local Volume. This scatter is larger than predicted from current simulations. This comparison between Local Volume hosts has also shown a potential relationship between the satellite LF, the star forming fraction and the host galaxy environment. It is clear that further observations of the faint end of satellite LFs for more galaxies are required in addition to work on simulations, to try and reproduce this large scatter and apparent environmental dependence.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23532401B