Benítez-Llambay, A.

The recent discovery of a starless dark matter halo

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Wednesday 10th
The recent discovery of a starless dark matter halo
In recent years, our theoretical understanding of what establishes the onset of galaxy formation on small scales has become increasingly mature, to the point that the halo occupation fraction, namely, the fraction of halos that host a luminous galaxy in their centre is now well understood in terms of the interplay between dark matter halo mass assembly histories and the existence of a redshift-dependent ""critical mass"" for galaxy formation. This enables predictions regarding the count of faint nearby dwarfs and some of their properties, including their gas fraction, neutral hydrogen content, and star formation histories, among others. Interestingly, these models also predict the existence of a population of starless halos with masses just under the critical mass. These starless halos elude the complexities associated with star formation and the subsequent supernova feedback and contain enough neutral hydrogen to produce a significant emission in 21 cm. In this talk, I will discuss these systems in the context of a recent detection of extended 21 cm emission consistent with a starless dark matter halo carried out with the Five-hundred Aperture Radio Telescope (FAST). I will also discuss how these observations can be used to constrain the nature of dark matter, the LCDM, and galaxy formation models at the smallest scales. I will end by discussing current uncertainties, ongoing observational programmes, and future theoretical and observational directions that may lead to further improvements.