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The chosen few : the low-mass haloes that host faint galaxies.

Sawala, Till and Frenk, Carlos S. and Fattahi, Azadeh and Navarro, Julio F. and Theuns, Tom and Bower, Richard G. and Crain, Robert A. and Furlong, Michelle and Jenkins, Adrian and Schaller, Matthieu and Schaye, Joop (2016) 'The chosen few : the low-mass haloes that host faint galaxies.', Monthly notices of the Royal Astronomical Society., 456 (1). pp. 85-97.


Since reionization prevents star formation in most haloes less massive than 3 × 109 M⊙, dwarf galaxies only populate a fraction of existing dark matter haloes. We use hydrodynamic cosmological simulations of the Local Group to study the discriminating factors for galaxy formation in the early Universe and connect them to the present-day properties of galaxies and haloes. A combination of selection effects related to reionization, and the subsequent evolution of haloes in different environments, introduces strong biases between the population of haloes that host dwarf galaxies, and the total halo population. Haloes that host galaxies formed earlier and are more concentrated. In addition, haloes more affected by tidal stripping are more likely to host a galaxy for a given mass or maximum circular velocity, vmax, today. Consequently, satellite haloes are populated more frequently than field haloes, and satellite haloes of 108–109 M⊙ or vmax of 12–20 km s−1, compatible with stellar kinematics of Local Group dwarf spheroidals, have experienced a greater than average reduction in both mass and vmax after infall. They are on closer, more radial orbits with higher infall velocities and earlier infall times. Together, these effects make dwarf galaxies highly biased tracers of the underlying dark matter distribution.

Item Type:Article
Keywords:Methods: numerical, Galaxies: dwarf, Galaxies: formation, Local Group, Cosmology: theory.
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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:03 November 2015
Date deposited:23 February 2016
Date of first online publication:11 December 2015
Date first made open access:No date available

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