Leo I: the classical dwarf spheroidal galaxy with the highest dark-matter density

Abstract

Dwarf spheroidal galaxies (dSphs) are known for being strongly dominated by dark matter (DM), which makes them convenient targets for investigating the DM nature and distribution. Recently, renewed interest in the dSph Leo I has resulted from claims suggesting the presence of a central supermassive black hole (BH), with mass estimates that challenge the typical expectations for dSphs, which are generally thought to host intermediate-mass black holes (IMBHs). However, Pascale et al. 2024 presented new upper limits on the BH mass, which are consistent with the range for IMBHs, solving the concerns raised in previous studies. Building on the analysis of Pascale et al. 2024, we examine the DM properties of Leo I inferred from the dynamical models of that paper. Our results indicate that Leo I is the galaxy with the highest DM density among the classical dSphs, with a central DM density (measured at a distance of $150$ pc from the galaxy centre) ${\rho }_{150}=35.5_{-4.7}^{+3.8}\times 10^7{M}_{\odot }$kpc${}^{-3}$. The DM density profile has logarithmic slope ${\gamma }_{150}=-0.89_{-0.17}^{+0.21}$ at $150$ pc, in line with literature values. At smaller distances the DM distribution flattens into a core, with a core radius of $r_c=72_{-32}^{+40}$ pc. Combined with the small pericentric distance of Leo I's orbit in the Milky Way, the new estimate of ${\rho }_{150}$ makes Leo I decisive in the study of the anticorrelation between pericentre and central DM density, and suggests that the anticorrelation could be significantly steeper and more pronounced than previously estimated. Despite its DM dominance, Leo I does not emerge as the most favorable target for indirect DM detection: the inferred DM decay $D$ and annihilation $J$ factors, $\log D(0.5^{\circ })$ [GeV cm${}^{-2}$] = $17.94_{-0.25}^{+0.17}$ and $\log J(0.5^{\circ })$ [GeV${}^2$ cm${}^{-5}$]= $18.13_{-0.18}^{+0.17}$ are consistent with previous estimates.

arXiv comment10 pages, 4 figures, accepted for publication in A&A

References in corpus (58)

• The Structure of Cold Dark Matter Halos
• The observed properties of dwarf galaxies in and around the Local Group
• Ultralight scalars as cosmological dark matter
• Small-Scale Challenges to the $\Lambda$CDM Paradigm
• Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi-LAT Data
• The Core-Cusp Problem
• Merger rates in hierarchical models of galaxy formation. II: Comparison with N-body simulations
• A Universal Mass Profile for Dwarf Spheroidal Galaxies?
• Analytical Models For Galactic Nuclei
• Cuspy No More: How Outflows Affect the Central Dark Matter and Baryon Distribution in Lambda CDM Galaxies
• Gaia Data Release 2: Kinematics of globular clusters and dwarf galaxies around the Milky Way
• AGAMA: Action-based galaxy modelling architecture
• A common mass scale for satellite galaxies of the Milky Way
• The Observed properties of Dark Matter on small spatial scales
• Mass loss from dwarf spheroidal galaxies: the origins of shallow dark matter cores and exponential surface brightness profiles
• The accretion history of dark matter halos III: A physical model for the concentration-mass relation
• Gaia DR2 Proper Motions of Dwarf Galaxies within 420 kpc: Orbits, Milky Way Mass, Tidal Influences, Planar Alignments, and Group Infall
• Dark matter heats up in dwarf galaxies
• The Galaxy Luminosity Function at z < 0.05: Dependence on Morphology
• The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?
• A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters
• Deviations from the Local Hubble Flow. I. The Tip of the Red Giant Branch as a Distance Indicator
• Dwarf galaxy annihilation and decay emission profiles for dark matter experiments
• The tidal stripping of satellites
• Dark matter annihilation and decay in dwarf spheroidal galaxies: The classical and ultrafaint dSphs
• Gaia early DR3 systemic motions of Local Group dwarf galaxies and orbital properties with a massive Large Magellanic Cloud
• Stellar kinematics and metallicities in the Leo I dwarf spheroidal galaxy -- wide field implications for galactic evolution
• The Space Motion of Leo I: Hubble Space Telescope Proper Motion and Implied Orbit
• Constraining Velocity-dependent Self-Interacting Dark Matter with the Milky Way's dwarf spheroidal galaxies
• Too Big To Fail in Light of Gaia
• Diversity of dark matter density profiles in the Galactic dwarf spheroidal satellites
• Early flattening of dark matter cusps in dwarf spheroidal galaxies
• Dark matter annihilation and decay from non-spherical dark halos in the Galactic dwarf satellites
• Faint dwarfs as a test of DM models: WDM vs. CDM
• A Global Analysis of Dark Matter Signals from 27 Dwarf Spheroidal Galaxies using 11 Years of Fermi-LAT Observations
• How to break the density-anisotropy degeneracy in spherical stellar systems
• Model comparison of the dark matter profiles of Fornax, Sculptor, Carina and Sextans
• Simple J-Factors and D-Factors for Indirect Dark Matter Detection
• Phase Space Models of the Dwarf Spheroidal Galaxies
• The distance to the Leo I dwarf spheroidal galaxy from the Red Giant Branch Tip
• The Milky Way's Halo and Subhalos in Self-Interacting Dark Matter
• A centrally heated dark halo for our Galaxy
• Self-consistent flattened isochrone models
• Dynamical models for the Sculptor dwarf spheroidal in a Lambda CDM universe
• Action-based dynamical models of dwarf spheroidal galaxies: application to Fornax
• Euclid: Early Release Observations -- Programme overview and pipeline for compact- and diffuse-emission photometry
• Effective $J$-factors for Milky Way dwarf spheroidal galaxies with velocity-dependent annihilation
• Dissecting the stellar content of Leo I: a dwarf irregular caught in transition
• Dynamical analysis of the dark matter and central black hole mass in the dwarf spheroidal Leo I
• Euclid: Early Release Observations -- Deep anatomy of nearby galaxies
• Investigating the effect of Milky Way dwarf spheroidal galaxies extension on dark matter searches with Fermi-LAT data
• Constraining Self-Interacting Dark Matter with Dwarf Spheroidal Galaxies and High-resolution Cosmological $N$-body Simulations
• Action-based models for dwarf spheroidal galaxies and globular clusters
• The central black hole in the dwarf spheroidal galaxy Leo I Not supermassive, at most an intermediate-mass candidate
• Search for gamma-ray emission from the 12 nearby dwarf spheroidal galaxies with 12 years of Fermi-LAT data
• On the anti-correlation between pericentric distance and inner dark matter density of Milky Way's dwarf spheroidal galaxies
• Extreme Tidal Stripping May Explain the Overmassive Black Hole in Leo I: a Proof of Concept
• Diving into dangerous tides: The impact of galaxy cluster tidal environments on satellite galaxy mass densities

Cited by in corpus (2)

• GravSphere2: A higher-order Jeans method for mass-modeling spherical stellar systems
• Multi-component, axisymmetric dynamical models of dSphs based on distribution functions: inferences on dark matter and intermediate-mass black holes in Draco and Ursa Minor