Neutralino dark matter stars can not exist

Abstract

Motivated by the recent "Cosmos Project" observation of dark-matter concentrations with no ordinary matter in the same place, we study the question of the existence of compact objects made of pure dark matter. We assume that the dark matter is neutralino, and compare its elastic and annihilation cross sections. We find that the two cross sections are of the same order of magnitude. This result has a straightforward and important consequence that neutralinos comprising a compact object can not achieve thermal equilibrium. To substantiate our arguments, by solving Oppenheimer-Volkoff equation we constructed a model of the star made of pure neutralinos. We explicitly showed that the condition for the thermal equilibrium supported by the Fermi pressure is never fulfilled inside the star. This neutralino state can not be described by the Fermi-Dirac distribution. Thus, a stable neutralino star, which is supported by the Fermi pressure, can not exist. We also estimated that a stable star can not contain more than a few percents of neutralinos, most of the mass must be in the form of the standard model particles.

published in JHEP

References in corpus (13)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• A direct empirical proof of the existence of dark matter
• Observation of an anomalous positron abundance in the cosmic radiation
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• The WIMPless Miracle: Dark Matter Particles without Weak-scale Masses or Weak Interactions
• Dark Matter and Dark Radiation
• Dark matter maps reveal cosmic scaffolding
• Dark matter and the first stars: a new phase of stellar evolution
• Compact stars made of fermionic dark matter
• A Natural Supersymmetric Model with MeV Dark Matter
• Galactic 511 keV line from MeV millicharged dark matter
• Constraints on dark matter particles charged under a hidden gauge group from primordial black holes
• Equation of State for Neutralino Star as a Form of Cold Dark Matter

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• Neutron Stars and Dark Matter
• On the change of old neutron star masses with galactocentric distance
• Electroweak stars: how nature may capitalize on the standard model's ultimate fuel
• Properties of Gravitationally Bound Dark Compact Ultra Dense Objects
• Neutron star mass in dark matter clumps
• Exotic quantum statistics and thermodynamics from a number-conserving theory of Majorana fermions