The Cold Dark Matter Halos of Local Group Dwarf Spheroidals

By J. Peñarrubia, A. McConnachie, J. Navarro. 2007

156 citations recorded by the source corpus.

We use N-body simulations to study the evolution of dwarf spheroidal galaxies (dSphs) driven by galactic tides. We adopt a cosmologically motivated model in which dSphs are approximated by a King model embedded in an NFW halo. We find that these NFW-embedded King models are extraordinarily resilient to tides; the stellar density profile still resembles a King model even after losing more than 99% of the stars. As tides strip the galaxy, the stellar luminosity, velocity dispersion, central surface brightness, and core radius decrease monotonically. Remarkably, we find that the evolution of these parameters is solely controlled by the total amount of mass lost from within the luminous radius. Of all parameters, the core radius is the least affected: after losing 99% of the stars, Rc decreases by just a factor of ~2. Interestingly, tides tend to make dSphs more dark matter dominated because the tightly bound central dark matter “cusp” is more resilient to disruption than the “cored” King profile. We examine whether the extremely large mass-to-light ratios of the newly discovered ultrafaint dSphs might have been caused by tidal stripping of once brighter systems. Although dSph tidal evolutionary tracks parallel the observed scaling relations in the luminosity-radius plane, they predict too steep a change in velocity dispersion compared with the observational estimates hitherto reported in the literature. The ultrafaint dwarfs are thus unlikely to be the tidal remnants of systems like Fornax, Draco, or Sagittarius. Despite spanning four decades in luminosity, dSphs appear to inhabit halos of comparable peak circular velocity, lending support to scenarios that envision dwarf spheroidals as able to form only in halos above a certain mass threshold.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0ab9fa34b1cd237f37dc5b516b1d69aeadbb2d21

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Citations in the corpus

A UNIVERSAL MASS PROFILE FOR DWARF SPHEROIDAL GALAXIES? (2009, methodology): “According to the tidal tracks provided by the N-body simulations of Peñarrubia et al. (2008b), the long-term effect of tidal stripping is to reduce a dSph’s velocity dispersion faster than its size.”
Local-Group tests of dark-matter concordance cosmology - Towards a new paradigm for structure formation (2010, background): “But the observed satellites do not show an increasing trend of luminosity with DM mass, according to Mateo (1998), Peñarrubia et al. (2008), and Strigari et al. (2008).”
THE COUPLING BETWEEN THE CORE/CUSP AND MISSING SATELLITE PROBLEMS (2012, methodology): “Given that stars are deeply embedded within the CDM halos of dSphs,rh ∼ 0.1rs (Peñarrubia et al. 2008), we consider minimum core sizes 70≤ rc,min/pc≤ 370 for haloes withMvir/M⊙ ∼ 108−11.”
The Most Dark-Matter-dominated Galaxies: Predicted Gamma-Ray Signals from the Faintest Milky Way Dwarfs (2007, background): “These galaxies may have been tidally stripped before (for example, if their orbit took them closer to the center of theMW); however, the stellar core that has survived is faithfully tracing the local potential (Piatek & Pryor 1995; Klimentowski et al. 2007; Peñarrubia et al. 2008).”
WHY BARYONS MATTER: THE KINEMATICS OF DWARF SPHEROIDAL SATELLITES (2012, background): “The comparable velocities of Draco (MV = −8.8), and Fornax (MV = −13.4), for example, have led Peñarrubia et al. (2008) to conclude that Draco formed in a halo 5 times more massive than Fornax, despite being 70 times fainter.”
ACCURATE STELLAR KINEMATICS AT FAINT MAGNITUDES: APPLICATION TO THE BOÖTES I DWARF SPHEROIDAL GALAXY (2011, background): “Accepting the equilibrium assumption, and using just radial velocities, several recent studies showed that the most robust mass it is possible to estimate for faint dwarfs is the mass enclosed within the half light radius (Penarrubia et al 2008; Walker et al. 2009; Wolf et al. 2010).”
The Local Group on FIRE: dwarf galaxy populations across a suite of hydrodynamic simulations (2018, result): “For example, Sawala et al. (2016b) showed that the number of luminous subhaloes in the APOSTLE simulations above a given Vmax agrees with estimates for the MW satellite population from Peñarrubia et al. (2008).”
Subhaloes in self-interacting galactic dark matter haloes (2012, background): “Models that successfully reproduce the observed data tend to have roughly the same value of the enclosed mass within the half-light radius (e.g. Strigari et al. 2007; Peñarrubia et al. 2008; Walker et al. 2009; Wolf et al. 2010).”
A BARYONIC SOLUTION TO THE MISSING SATELLITES PROBLEM (2012, background): “Adopting 97% is conservative, as both Z12 and Peñarrubia et al. (2008) found that halos begin to have their stars stripped after losing 90% of their halo mass after infall.”
A Comprehensive Maximum Likelihood Analysis of the Structural Properties of Faint Milky Way Satellites (2008, background): “Moreover, the importance of the Peñarrubia et al. (2008b) caveat depends, for each satellite, on the amount of stellar loss, which is all but constrained.”
Accurate masses for dispersion-supported galaxies (2009, background): “…cluster systems, the majority of the mass in dwarf galaxies does not necessarily follow the shape of their baryonic tracers (e.g., Sofue & Rubin 2001; Walker et al. 2007; Peñarrubia et al. 2008), as they are likely to be deeply embedded inside of dark matter halos (e.g., White & Rees 1978).”
Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud (2019, methodology): “Instead, we build a mock smooth stellar halo using a weighting scheme implemented by Laporte et al. (2013a,b) (see also, Bullock & Johnston 2005; Peñarrubia et al. 2008).”
Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function (2008, result): “We note that strong CDM priors suggest somewhat larger vmax values (k15 km s 1; Strigari et al. 2007b, 2008b; Peñarrubia et al. 2008), which would (if anything) underpredict the observed visible satellite counts, according to our estimates.”
The Milky Way’s bright satellites as an apparent failure of ΛCDM (2011, background): “We find somewhat smaller Vmax values for Draco, Leo I, Ursa Minor, and Sculptor than Peñarrubia et al. (2008), likely because they adopted the Vmax − rmax relation for field dark matter halos: Springel et al. (2008) find that the Aquarius subhalos are systematically denser than field halos, with…”
The missing massive satellites of the Milky Way (2012, background): “The latter correlates strongly with the total dark mass of the dwarf, which is usually expressed in terms of its maximum circular velocity, Vmax, a quantity less affected than mass by tidal stripping (Peñarrubia et al. 2008).”
Luminosity function and radial distribution of Milky Way satellites in a ΛCDM Universe (2009, background): “In the K08 models, a subhalo is considered to be tidally destroyed if it either loses more than 98% of its mass (e.g. Penarrubia et al. 2008) or if its mass falls below 6.5 × 106M⊙, which is the minimum mass observed for Milky Way satellites (Strigari et al. 2008).”
A METHOD FOR MEASURING (SLOPES OF) THE MASS PROFILES OF DWARF SPHEROIDAL GALAXIES (2011, background): “…component during a close pericentricpassage and/or by stripping stars that, thence unbound, linger 16 sufficiently near the dSph to be observed and counted as bound members (e.g., Piatek & Pryor 1995; Oh et al. 1995; Read et al. 2006; Klimentowski et al. 2007; Peñarrubia et al. 2008b, 2009).”
MULTI-ELEMENT ABUNDANCE MEASUREMENTS FROM MEDIUM-RESOLUTION SPECTRA. III. METALLICITY DISTRIBUTIONS OF MILKY WAY DWARF SATELLITE GALAXIES (2010, background): “The dwarf galaxies of the Local Group less luminous than Fornax seem to inhabit dark matter halos of similar mass (Mateo 1998; Peñarrubia et al. 2008; Strigari et al. 2008; Walker et al. 2009).”