Dwarf Galaxies as Cosmological Probes

Abstract

The Lambda Cold Dark Matter (LCDM) paradigm makes specific predictions for the abundance, structure, substructure and clustering of dark matter halos, the sites of galaxy formation. These predictions can be directly tested, in the low-mass halo regime, by dark matter-dominated dwarf galaxies. A number of potential challenges to LCDM have been identified when confronting the expected properties of dwarfs with observation. I review our understanding of a few of these issues, including the `missing satellites' and the `too-big-to-fail' problems, and argue that neither poses an insurmountable challenge to LCDM. Solving these problems requires that most dwarf galaxies inhabit halos of similar mass, and that there is a relatively sharp minimum halo mass threshold to form luminous galaxies. These predictions are eminently falsifiable. In particular, LCDM predicts a large number of `dark' low-mass halos, some of which should have retained enough primordial gas to be detectable in deep 21 cm or H${}_{\alpha }$ surveys. Detecting this predicted population of `mini-halos' would be a major discovery and a resounding success for LCDM on small scales.

Invited review at IAU Symposium 344, Dwarf Galaxies: From the Deep Universe to the Present

References in corpus (11)

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• Too big to fail? The puzzling darkness of massive Milky Way subhaloes
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• A Catalog of Ultra-compact High Velocity Clouds from the ALFALFA Survey: Local Group Galaxy Candidates?
• The properties of "dark" ΛCDM halos in the Local Group
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Cited by in corpus (4)

• Probing sub-galactic mass structure with the power spectrum of surface-brightness anomalies in high-resolution observations of galaxy-galaxy strong gravitational lenses. II.Observational constraints on the sub-galactic matter power spectrum
• A Search for Satellite Galaxies of Nearby Star-Forming Galaxies with Resolved Stars in LBT-SONG
• Multiple locations of near-infrared coronal lines in NGC 5548
• Metamorphosis of dwarf halo density profile under dark matter decays