1206.5412 (Go Ogiya et al.)

The core-cusp problem in cold dark matter halos and supernova feedback: Effects of Oscillation    [PDF]

Go Ogiya, Masao Mori

We investigate the dynamical response of dark matter halos against recurrent starbursts in forming less-massive galaxies to solve the core-cusp problem, which is a discrepancy between the observation and the cold dark matter model. The gas heated by supernova feedbacks after a starburst expands, and then the star formation terminates. This expanding gas loses energy by radiative cooling, and then falls back toward the galactic center. Subsequently, a starburst arises again. This cycle of expansion and contraction of the interstellar gas leads to the recursive change in the gravitational potential of the interstellar gas. The resonance between dark matter particles and the density wave excited by the oscillating potential plays a key role to understand the physical mechanism of the cusp-core transition of dark matter halos. The dark matter halos effectively gain the kinetic energy from the energy transfer driven by the resonance between particles and the density waves. We find the critical condition for the cusp-core transition that the oscillation period of the gas potential should be approximately the same as the local dynamical time of the dark matter halo. We present the resultant core radius of the dark matter halo after the cusp-core transition induced by the resonance using the conventional mass-density profile predicted by the cold dark matter models. Moreover, we verified the analytical model using $N$-body simulations and the results nicely confirm the resonance model.

View original: http://arxiv.org/abs/1206.5412