An Off-center Density Peak in the Milky Way's Dark Matter Halo?

Abstract

We show that the position of the central dark matter density peak may be expected to differ from the dynamical center of the Galaxy by several hundred parsec. In Eris, a high resolution cosmological hydrodynamics simulation of a realistic Milky-Way-analog disk galaxy, this offset is 300 - 400 pc (~3 gravitational softening lengths) after z=1. In its dissipationless dark-matter-only twin simulation ErisDark, as well as in the Via Lactea II and GHalo simulations, the offset remains below one softening length for most of its evolution. The growth of the DM offset coincides with a flattening of the central DM density profile in Eris inwards of ~1 kpc, and the direction from the dynamical center to the point of maximum DM density is correlated with the orientation of the stellar bar, suggesting a bar-halo interaction as a possible explanation. A dark matter density offset of several hundred parsec greatly affects expectations of the dark matter annihilation signals from the Galactic Center. It may also support a dark matter annihilation interpretation of recent reports by Weniger (2012) and Su & Finkbeiner (2012) of highly significant 130 GeV gamma-ray line emission from a region 1.5 degrees (~200 parsec projected) away from Sgr A* in the Galactic plane.

12 pages, 11 figures, replaced with version accepted for publication in ApJ

References in corpus (13)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope
• Dynamical friction in constant density cores: a failure of the Chandrasekhar formula
• Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
• Dynamical Centers and Non-Circular Motions in THINGS Galaxies: Implications for Dark Matter Halos
• Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin of Diffuse High Energy Emission from the Inner 2deg by 1deg of the Galactic Center
• Fermi 130 GeV gamma-ray excess and dark matter annihilation in sub-haloes and in the Galactic centre
• Resonances in Barred Galaxies
• Cold ultrarelativistic pulsar winds as potential sources of galactic gamma-ray lines above 100 GeV
• An optimum time-stepping scheme for N-body simulations
• The 130 GeV Fingerprint of Right-Handed Neutrino Dark Matter
• Measurement of non-axisymmetry in centres of advanced mergers of galaxies

Cited by in corpus (46)

• The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter
• Cold dark matter heats up
• Double-Disk Dark Matter
• Astrochemistry During the Formation of Stars
• Galactic Searches for Dark Matter
• In Wino Veritas? Indirect Searches Shed Light on Neutralino Dark Matter
• Limits on Dark Matter Annihilation Signals from the Fermi LAT 4-year Measurement of the Isotropic Gamma-Ray Background
• Velocity Bias from the Small Scale Clustering of SDSS-III BOSS Galaxies
• The Distribution of Dark Matter in the Milky Way's Disk
• Dark Matter Interpretation of the Fermi-LAT Observation Toward the Galactic Center
• Pseudobulge Formation as a Dynamical Rather than a Secular Process
• Strong constraints on thermal relic dark matter from Fermi-LAT observations of the Galactic Center
• Search for Gamma-ray Emission from Dark Matter Annihilation in the Large Magellanic Cloud with the Fermi Large Area Telescope
• Enhanced diphoton rates at Fermi and the LHC
• Constraints on Galactic Wino Densities from Gamma Ray Lines
• Questioning a 3.5 keV dark matter emission line
• Constraints on an Annihilation Signal from a Core of Constant Dark Matter Density around the Milky Way Center with H.E.S.S
• Search for 511 keV Emission in Satellite Galaxies of the Milky Way with INTEGRAL/SPI
• Dark matter annihilation radiation in hydrodynamic simulations of Milky Way haloes
• When H II Regions are Complicated: Considering Perturbations from Winds, Radiation Pressure, and Other Effects
• Neutralino dark matter and the Fermi gamma-ray lines
• Galactic Center Radio Constraints on Gamma-Ray Lines from Dark Matter Annihilation
• The 511 keV Excess and Primordial Black Holes
• The offsets between galaxies and their dark matter in Lambda-CDM
• Semi-Inclusive Wino and Higgsino Annihilation to LL'
• Gamma rays from the Galactic Centre region: a review
• Exact expressions for the pericenter precession caused by some Dark Matter distributions and constraints on them from orbital motions in the Solar System, in the double pulsar and in the Galactic center
• Asymmetric mass models of disk galaxies - I. Messier 99
• The 130 GeV gamma-ray line and generic dark matter model building constraints from continuum gamma rays, radio and antiproton data
• Antimatter in the Universe : Constraints from Gamma-Ray Astronomy
• The evolution of dwarf galaxy satellites with different dark matter density profiles in the ErisMod simulations. I. The early infalls
• A Phantom Menace: On the Morphology of the Galactic Center Excess
• Measuring line-of-sight shear with Einstein rings: a proof of concept
• The Sensitivity of Future Gamma-Ray Telescopes to Primordial Black Holes
• Genesis of morpho-kinematic lopsidedness in minor merger of galaxies
• A Clustering Analysis of the Morphology of the 130 GeV Gamma-Ray Feature
• Detection of positron in-flight annihilation from the Galaxy
• Where are the Fermi Lines Coming From?
• Turbulent gas-rich discs at high redshift: origin of thick stellar discs through 3D 'baryon sloshing'
• Off-centred dark matter halo leading to strong central disc lopsidedness
• On the offset of the DM cusp and the interpretation of the 130 GeV line as a DM signal
• Constraining the distribution of dark matter in inner galaxy with indirect detection signal: The case of tentative 130 gev γ-ray line
• The spatial distribution of dark-matter-annihilation originated gamma-ray line signal
• Missing Lensed Images and the Galaxy Disk Mass in CXOCY J220132.8-320144
• Quantum Entanglement on Cosmological Scale
• Strategies for the Detection of Gamma Rays from Dark Matter Annihilation Towards the Galactic Center Region with the High Energy Stereoscopic System