SN-driven mechanism of cusp-core transformation: an appraisal

Abstract

We present and test an effective model for N -body simulations that aims at mimicking the impact of supernova (SN) feedback on the dark matter (DM) distribution of isolated halos hosting dwarf galaxies. Although the model is physically decoupled from the cosmological history of both the DM halo and the dwarf galaxy, it allows us to study the impact of different macroscopic parameters such as galaxy concentration, feedback energy and energy injection time in the process of SN-driven core formation in a physically clear way. Using our effective model in a suite of N-body simulations of an isolated halo with different SN feedback parameters, we find that whether or not a DM core forms is determined by the total amount of SN feedback energy that is transferred to the DM particles. At a fixed injected energy, the amount of transferred energy is bigger - and the size of the DM core is larger - the faster the energy injection occurs and the more compact the dwarf galaxy is. Analyzing the orbital evolution of kinematic tracers, we demonstrate that a core forms through SN feedback only if the energy injection is impulsive relative to the dynamical timescale of particles in the inner halo. However, there is no fundamental link between the total amount of injected energy and the injection rate. Consequently, the presence of signatures of impulsive changes of the gravitational potential is not a sufficient condition for dwarf-size halos to have cored density profiles.

25 pages, 7 figures, to appear in the Astrophysical Journal (in press)

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• The cusp-core problem in gas-poor dwarf spheroidal galaxies
• The Response of Dark Matter Haloes to Gas Ejection: CuspCore II
• Gravothermal collapse of Self-Interacting Dark Matter halos as the Origin of Intermediate Mass Black Holes in Milky Way satellites
• Real and counterfeit cores: how feedback expands halos and disrupts tracers of inner gravitational potential in dwarf galaxies
• The Quest for the Nature of the Dark Matter: The Need of a New Paradigm
• X-ray morphology of cluster-mass haloes in self-interacting dark matter
• Constraining neutrino-DM interactions with Milky Way dwarf spheroidals and supernova neutrinos
• Kinematic signatures of impulsive supernova feedback in dwarf galaxies
• Segue 2 Recently Collided with the Cetus-Palca Stream: New Opportunities to Constrain Dark Matter in an Ultra-Faint Dwarf