Pressure from dark matter annihilation and the rotation curve of spiral galaxies

Abstract

The rotation curves of spiral galaxies are one of the basic predictions of the cold dark matter paradigm, and their shape in the innermost regions has been hotly debated over the last decades. The present work shows that dark matter annihilation into electron-positron pairs may affect the observed rotation curve by a significant amount. We adopt a model-independent approach, where all the electrons and positrons are injected with the same initial energy E_0 ~ m_dm*c^2 in the range from 1 MeV to 1 TeV and the injection rate is constrained by INTEGRAL, Fermi, and HESS data. The pressure of the relativistic electron-positron gas is determined by solving the diffusion-loss equation, considering inverse Compton scattering, synchrotron radiation, Coulomb collisions, bremsstrahlung, and ionization. For values of the gas density and magnetic field that are representative of the Milky Way, it is estimated that pressure gradients are strong enough to balance gravity in the central parts if E_0 < 1 GeV. The exact value depends somewhat on the astrophysical parameters, and it changes dramatically with the slope of the dark matter density profile. For very steep slopes, as those expected from adiabatic contraction, the rotation curves of spiral galaxies would be affected on ~kpc scales for most values of E_0. By comparing the predicted rotation curves with observations of dwarf and low surface brightness galaxies, we show that the pressure from dark matter annihilation may improve the agreement between theory and observations in some cases, but it also imposes severe constraints on the model parameters (most notably, the inner slope of halo density profile, as well as the mass and the annihilation cross-section of dark matter particles into electron-positron pairs).

14 pages, 10 figures

References in corpus (35)

• Observation of an anomalous positron abundance in the cosmic radiation
• High-Resolution Rotation Curves and Galaxy Mass Models from THINGS
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• The Core-Cusp Problem
• A new measurement of the antiproton-to-proton flux ratio up to 100 GeV in the cosmic radiation
• The redshift dependence of the structure of massive LCDM halos
• CMB constraints on Dark Matter models with large annihilation cross-section
• Cosmological puzzle resolved by stellar feedback in high redshift galaxies
• A blueprint for detecting supersymmetric dark matter in the Galactic halo
• Dark matter and the first stars: a new phase of stellar evolution
• GHASP : an H alpha kinematic survey of spiral and irregular galaxies. V. Dark matter distribution in 36 nearby spiral galaxies
• Galactic secondary positron flux at the Earth
• Evidence Of Dark Matter Annihilations In The WMAP Haze
• Impact of dark matter decays and annihilations on reionization
• Contraints on radiative dark-matter decay from the cosmic microwave background
• Inverse Compton constraints on the Dark Matter e+e- excesses
• THINGS about MOND
• Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
• The Effects of Dark Matter Decay and Annihilation on the High-Redshift 21 cm Background
• Multi-wavelength signals of dark matter annihilations at the Galactic center
• The impacts of dark matter particle annihilation on recombination and the anisotropies of the cosmic microwave background
• The impact of dark matter decays and annihilations on the formation of the first structures
• Constraining DM through 21 cm observations
• Effects of Dark Matter Annihilation on the Cosmic Microwave Background
• Anisotropy probe of galactic and extra-galactic Dark Matter annihilations
• The dynamical structure of dark matter haloes
• Radio and gamma-ray constraints on dark matter annihilation in the Galactic center
• First star formation with dark matter annihilation
• Annihilation vs. Decay: Constraining dark matter properties from a gamma-ray detection
• Impact of Dark Matter Annihilation on the High-Redshift Intergalactic Medium
• SZ effect from Dark Matter annihilation
• Multi-messenger constraints on the annihilating dark matter interpretation of the positron excess
• Effect of dark matter annihilation on gas cooling and star formation
• Consequences of dark matter self-annihilation for galaxy formation
• Photons from Dark Matter in a (non-Universal) Extra Dimension model

Cited by in corpus (9)

• A black box for dark sector physics: Predicting dark matter annihilation feedback with conditional GANs
• The First Billion Years project: dark matter haloes going from contraction to expansion and back again
• Multi-messenger constraints on dark matter annihilation into electron-positron pairs
• Heating of galactic gas by dark matter annihilation in ultracompact minihalos
• Effects of Chameleon Scalar Field on Rotation Curves of the Galaxies
• Effects of dark matter pressure on the ellipticity of cosmic voids
• Dark Matter Annihilation Feedback in cosmological simulations I: Code convergence and idealised halos
• Accelerated expansion of the Universe in the Presence of Dark Matter Pressure
• Dark Matter Annihilation Feedback in Cosmological Simulations II: The Influence on Gas and Halo Structure