The effect of tides on the Sculptor dwarf spheroidal galaxy

Abstract

Dwarf spheroidal galaxies (dSphs) appear to be some of the most dark matter dominated objects in the Universe. Their dynamical masses are commonly derived using the kinematics of stars under the assumption of equilibrium. However, these objects are satellites of massive galaxies (e.g.\ the Milky Way) and thus can be influenced by their tidal fields. We investigate the implication of the assumption of equilibrium focusing on the Sculptor dSph by means of ad-hoc $N$-body simulations tuned to reproduce the observed properties of Sculptor following the evolution along some observationally motivated orbits in the Milky Way gravitational field. For this purpose, we used state-of-the-art spectroscopic and photometric samples of Sculptor's stars. We found that the stellar component of the simulated object is not directly influenced by the tidal field, while $\approx 30\%-60\%$ the mass of the more diffuse DM halo is stripped. We conclude that, considering the most recent estimate of the Sculptor proper motion, the system is not affected by the tides and the stellar kinematics represents a robust tracer of the internal dynamics. In the simulations that match the observed properties of Sculptor, the present-day dark-to-luminous mass ratio is $\approx 6$ within the stellar half-light radius ($\approx 0.3$ kpc) and $>50$ within the maximum radius of the analysed dataset ($\approx 1.5^{\circ }\approx 2$ kpc).

19 pages, 10 figures, accepted for publication in MNRAS. V3: updated after editor comments See our playlist for simulation videos: https://av.tib.eu/series/633/supplemental+videos+of+the+paper+the+effect+of+tides+on+the+sculptor+dwarf+spheroidal+galaxy

References in corpus (36)

• The Gaia mission
• galpy: A Python Library for Galactic Dynamics
• Too big to fail? The puzzling darkness of massive Milky Way subhaloes
• The Milky Way's Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from Kinematics of ~2400 SDSS Blue Horizontal Branch Stars
• The Star Formation Histories of Local Group Dwarf Galaxies I. Hubble Space Telescope / Wide Field Planetary Camera 2 Observations
• The Observed properties of Dark Matter on small spatial scales
• The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
• The Tidal Evolution of Local Group Dwarf Spheroidals
• The kinematic status and mass content of the Sculptor dwarf spheroidal galaxy
• Stellar Velocities in the Carina, Fornax, Sculptor and Sextans dSph Galaxies: Data from the Magellan/MMFS Survey
• "Skinny Milky Way, Please", says Sagittarius
• The NIR Ca II triplet at low metallicity - Searching for extremely low-metallicity stars in classical dwarf galaxies
• The stellar mass-halo mass relation of isolated field dwarfs: a critical test of $\Lambda$CDM at the edge of galaxy formation
• The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?
• Constraining the Galaxy's dark halo with RAVE stars
• Exploring Halo Substructure with Giant Stars XI: The Tidal Tails of the Carina Dwarf Spheroidal and the Discovery of Magellanic Cloud Stars in the Carina Foreground
• Scaling Relations and the Fundamental Line of the Local Group Dwarf Galaxies
• Exploring Halo Substructure with Giant Stars X. Extended Dark Matter or Tidal Disruption?: The Case for the Leo I Dwarf Spheroidal Galaxy
• Exploring Halo Substructure with Giant Stars: The Dynamics and Metallicity of the Dwarf Spheroidal in Bootes
• Stellar kinematics in the remote Leo II dwarf spheroidal galaxy -- Another brick in the wall
• 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
• The Araucaria Project. The Distance to the Sculptor dwarf spheroidal galaxy from infrared photometry of RR Lyrae stars
• Early flattening of dark matter cusps in dwarf spheroidal galaxies
• Systemic Proper Motions of Milky Way Satellites from Stellar Redshifts: the Carina, Fornax, Sculptor and Sextans Dwarf Spheroidals
• 3D motions in the Sculptor dwarf galaxy as a glimpse of a new era
• A discrete chemo-dynamical model of the dwarf spheroidal galaxy Sculptor: mass profile, velocity anisotropy and internal rotation
• Space Motions of the Dwarf Spheroidal Galaxies Draco and Sculptor based on HST Proper Motions with ~10-year Time Baseline
• The edge of galaxy formation II: evolution of Milky Way satellite analogues after infall
• The Effects of Ram-pressure Stripping and Supernova Winds on the Tidal Stirring of Disky Dwarfs: Enhanced Transformation into Dwarf Spheroidals
• Tracing the stellar component of low surface brightness Milky Way Dwarf Galaxies to their outskirts I: Sextans
• A low pre-infall mass for the Carina dwarf galaxy from disequilibrium modelling
• Understanding the internal dynamics of elliptical galaxies without non-baryonic dark matter
• Action-based models for dwarf spheroidal galaxies and globular clusters
• Complexity on dwarf galaxies scale: A bimodal distribution function in Sculptor
• Universal subhalo accretion in cold and warm dark matter cosmologies

Cited by in corpus (14)

• Gaia early DR3 systemic motions of Local Group dwarf galaxies and orbital properties with a massive Large Magellanic Cloud
• The Gas Content and Stripping of Local Group Dwarf Galaxies
• The last breath of the Sagittarius dSph
• Metallicity and $\alpha$-element Abundance Gradients along the Sagittarius Stream as Seen by APOGEE
• The stellar metallicity gradients of Local Group dwarf galaxies
• A 3D view of dwarf galaxies with Gaia and VLT/FLAMES I. The Sculptor dwarf spheroidal
• A portrait of the Vast Polar Structure as a young phenomenon: hints from its member satellites
• Joint Gas and Stellar Dynamical Models of WLM: An isolated dwarf galaxy within a cored, prolate DM halo
• An off-centred bulge or a satellite? Hydrodynamical $N$-body simulations of the disc galaxy NGC 5474
• Effective N-body models of composite collisionless stellar systems
• Tidal mass loss in the Fornax dwarf spheroidal galaxy through N-body simulations with Gaia DR3-based orbits
• Dynamical Friction and Tidal Interactions
• Broken Expectations: The Effects of Modelling Assumptions on the Inferred Dark Matter Distribution in the Milky Way's Satellites
• The tidal features of the classical Milky Way satellites: Expected in MOND but inconsistent with cold dark matter models