Dynamical analysis of the dark matter and central black hole mass in the dwarf spheroidal Leo I

Abstract

We measure the central kinematics for the dwarf spheroidal galaxy Leo I using integrated-light measurements and previously published data. We find a steady rise in the velocity dispersion from $300^{\prime \prime }$ into the center. The integrated-light kinematics provide a velocity dispersion of $11.76\pm 0.66$ km/s inside $75^{\prime \prime }$. After applying appropriate corrections to crowding in the central regions, we achieve consistent velocity dispersion values using velocities from individual stars. Crowding corrections need to be applied when targeting individual stars in high density stellar environments. From integrated light, we measure the surface brightness profile and find a shallow cusp towards the center. Axisymmetric, orbit-based models measure the stellar mass-to-light ratio, black hole mass and parameters for a dark matter halo. At large radii it is important to consider possible tidal effects from the Milky Way so we include a variety of assumptions regarding the tidal radius. For every set of assumptions, models require a central black hole consistent with a mass $(3.3\pm 2)\times 10^6{M}_{\odot }$. The no-black-hole case for any of our assumptions is excluded at over 95% significance, with $6.4<\Delta {\chi }^2<14$. A black hole of this mass would have significant effect on dwarf galaxy formation and evolution. The dark halo parameters are heavily affected by the assumptions for the tidal radii, with the circular velocity only constrained to be above 30 km/s. Reasonable assumptions for the tidal radius result in stellar orbits consistent with an isotropic distribution in the velocities. These more realistic models only show strong constraints for the mass of the central black hole.

References in corpus (26)

• Ultralight scalars as cosmological dark matter
• Too big to fail? The puzzling darkness of massive Milky Way subhaloes
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• A common mass scale for satellite galaxies of the Milky Way
• High-resolution mass models of dwarf galaxies from LITTLE THINGS
• The kinematic status and mass content of the Sculptor dwarf spheroidal galaxy
• The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?
• Surface Brightness Profiles of Galactic Globular Clusters from Hubble Space Telescope Images
• Exploring Halo Substructure with Giant Stars X. Extended Dark Matter or Tidal Disruption?: The Case for the Leo I Dwarf Spheroidal Galaxy
• The mass and velocity anisotropy of the Carina, Fornax, Sculptor and Sextans dwarf spheroidal galaxies
• The Space Motion of Leo I: Hubble Space Telescope Proper Motion and Implied Orbit
• Stellar kinematics in the remote Leo II dwarf spheroidal galaxy -- Another brick in the wall
• Dwarf Galaxy Dark Matter Density Profiles Inferred from Stellar and Gas Kinematics
• Modeling The Structure And Dynamics of Dwarf Spheroidal Galaxies with Dark Matter And Tides
• Mass modelling of dwarf spheroidal galaxies: the effect of unbound stars from tidal tails and the Milky Way
• On the Structure of Dark Matter Halos at the Damping Scale of the Power Spectrum with and without Relict Velocities
• A deep view into the nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. I. Data and stellar population characterization
• The binary fraction of stars in dwarf galaxies: the case of Leo II
• The Chemical Abundances of the Stellar Populations in the Leo I and Leo II dSph Galaxies
• A dwarf-dwarf merger and dark matter core as a solution to the Globular Cluster problems in the Fornax dSph
• Dissecting the stellar content of Leo I: a dwarf irregular caught in transition
• A Black Hole Mass Determination for the Compact Galaxy Mrk 1216
• The anatomy of Leo I: how tidal tails affect the kinematics
• Dynamical modelling of globular clusters: challenges for the robust determination of IMBH candidates
• NGC 307 and the Effects of Dark-Matter Haloes on Measuring Supermassive Black Holes in Disc Galaxies
• Streaming motion in Leo I

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• Accretion from Winds of Red Giant Branch Stars May Reveal the Supermassive Black Hole in Leo I
• Extreme Tidal Stripping May Explain the Overmassive Black Hole in Leo I: a Proof of Concept
• Dynamics of intermediate mass black holes in globular clusters. Wander radius and anisotropy profiles
• Intermediate-mass ratio inspirals in merging elliptical galaxies