Emergence of a stellar cusp by a dark matter cusp in a low-mass compact ultra-faint dwarf galaxy

Abstract

Recent observations have been discovering new ultra-faint dwarf galaxies as small as $\sim 20\mathrm{pc}$ in half-light radius and $\sim 3\mathrm{km}{\mathrm{s}}^{-1}$ in line-of-sight velocity dispersion. In these galaxies, dynamical friction on a star against dark matter can be significant and alter their stellar density distribution. The effect can strongly depend on a central density profile of dark matter, i.e. cusp or core. In this study, I perform computations using a classical and a modern analytic formulae and $N$-body simulations to study how dynamical friction changes a stellar density profile and how different it is between cuspy and cored dark matter haloes. This study shows that, if a dark matter halo has a cusp, dynamical friction can cause shrivelling instability which results in emergence of a stellar cusp in the central region $\simeq 2\mathrm{pc}$. On the other hand, if it has a constant-density core, dynamical friction is significantly weaker and does not generate a stellar cusp even if the galaxy has the same line-of-sight velocity dispersion. In such a compact and low-mass galaxy, since the shrivelling instability by dynamical friction is inevitable if it has a dark matter cusp, absence of a stellar cusp implies that the galaxy has a dark-matter core. I expect that this could be used to diagnose a dark matter density profile in these compact ultra-faint dwarf galaxies.

arXiv comment11 pages, 7 figures and 1 table. Submitted to MNRAS. The second referee report received and replied. Corrections made on Fig.7 and Appendix A

References in corpus (49)

• A Universal Density Profile from Hierarchical Clustering
• Evolutionary population synthesis: models, analysis of the ingredients and application to high-z galaxies
• The Aquarius Project: the subhalos of galactic halos
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• At the heart of the matter: the origin of bulgeless dwarf galaxies and Dark Matter cores
• How supernova feedback turns dark matter cusps into cores
• The Core-Cusp Problem
• The Observed properties of Dark Matter on small spatial scales
• Resolving the Structure of Cold Dark Matter Halos II
• Dark and luminous matter in THINGS dwarf galaxies
• A constant dark matter halo surface density in galaxies
• A New Milky Way Companion: Unusual Globular Cluster or Extreme Dwarf Satellite?
• NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows
• Breathing FIRE: How Stellar Feedback Drives Radial Migration, Rapid Size Fluctuations, and Population Gradients in Low-Mass Galaxies
• Does the Fornax dwarf spheroidal have a central cusp or core?
• Sagittarius II, Draco II and Laevens 3: three new Milky Way satellites discovered in the Pan-STARRS 1 3pi Survey
• GHASP : an H alpha kinematic survey of spiral and irregular galaxies. V. Dark matter distribution in 36 nearby spiral galaxies
• Segue 2: A Prototype of the Population of Satellites of Satellites
• A Necessary Condition for Individual Time-Steps in SPH Simulations
• A Density Independent Formulation of Smoothed Particle Hydrodynamics
• Dynamical friction in constant density cores: a failure of the Chandrasekhar formula
• Toward first-principle simulations of galaxy formation: I. How should we choose star formation criteria in high-resolution simulations of disk galaxies?
• Core creation in galaxies and haloes via sinking massive objects
• Weakening dark-matter cusps by clumpy baryonic infall
• Toward First-Principle Simulations of Galaxy Formation: II. Shock-Induced Starburst at a Collision Interface During the First Encounter of Interacting Galaxies
• Dynamical Friction around Supermassive Black Holes
• The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos
• A New Milky Way Satellite Discovered In The Subaru/Hyper Suprime-Cam Survey
• Scaling Laws for Dark Matter Halos in Late-Type and Dwarf Spheroidal Galaxies
• Dynamical friction of massive objects in galactic centres
• Dynamical friction in dwarf galaxies
• A semi-analytic dynamical friction model for cored galaxies
• Large scale inhomogeneity and local dynamical friction
• A Semi-Analytic dynamical friction model that reproduces core stalling
• Probing non-spherical dark halos in the Galactic dwarf galaxies
• Dynamical friction in cuspy galaxies
• The Core-Cusp Problem in Cold Dark Matter Halos and Supernova Feedback: Effects of Oscillation
• Phantom-GRAPE: numerical software library to accelerate collisionless $N$-body simulation with SIMD instruction set on x86 architecture
• Shallowed cusp slope of dark matter in disc galaxy formation through clump clusters
• FAST: A Fully Asynchronous Split Time-Integrator for Self-Gravitating Fluid
• The test for suppressed dynamical friction in a constant density core of dwarf galaxies
• Multimass spherical structure models for N-body simulations
• Is Draco II one of the faintest dwarf galaxies? First study from Keck/DEIMOS spectroscopy
• Wide binaries in ultra-faint galaxies: a window onto dark matter on the smallest scales
• Corrective effect of many-body interactions in dynamical friction
• Lack of nuclear clusters in dwarf spheroidal galaxies: implications for massive black holes formation and the cusp/core problem
• A common surface-density scale for the Milky Way and Andromeda dwarf satellites as a constraint on dark matter models
• A Natural Symmetrization for the Plummer Potential
• Theoretical lower limits on sizes of ultra faint dwarf galaxies from dynamical friction

Cited by in corpus (3)

• Gravitational probes of dark matter physics
• Dehnen halo effect on a black hole in an ultra-faint dwarf galaxy
• Gravitational radiation reaction around a static black hole surrounded by a Dehnen type dark matter halo