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.

10 pages, 4 figures, accepted for publication in A&A

References in corpus (23)

• Ultralight scalars as cosmological dark matter
• A common mass scale for satellite galaxies of the Milky Way
• The Observed properties of Dark Matter on small spatial scales
• The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?
• Dwarf galaxy annihilation and decay emission profiles for dark matter experiments
• 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
• Faint dwarfs as a test of DM models: WDM vs. CDM
• Early flattening of dark matter cusps in dwarf spheroidal galaxies
• A centrally heated dark halo for our Galaxy
• Euclid: Early Release Observations -- Programme overview and pipeline for compact- and diffuse-emission photometry
• 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
• Action-based models for dwarf spheroidal galaxies and globular clusters
• Constraining Self-Interacting Dark Matter with Dwarf Spheroidal Galaxies and High-resolution Cosmological $N$-body Simulations
• Search for gamma-ray emission from the 12 nearby dwarf spheroidal galaxies with 12 years of Fermi-LAT data
• The central black hole in the dwarf spheroidal galaxy Leo I Not supermassive, at most an intermediate-mass candidate
• 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

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