The Central Mass Distribution in Dwarf and Low Surface Brightness Galaxies

By R. Swaters, B. Madore, F. C. V. D. Bosch, M. Balcells. 2002

329 citations recorded by the source corpus.

We present high-resolution Hα rotation curves for a sample of 15 dwarf and low surface brightness galaxies. From these we derive limits on the slopes of the central mass distributions, using both a direct inversion of the rotation curves and detailed mass models. Assuming that the density distributions of dark matter halos follow a power law at small radii, ρ(r) ∝ r-α, we find inner slopes in the range 0 ≲ α ≲ 1 for most galaxies. Thus, even with the relatively high spatial resolution of the Hα rotation curves presented here, the inner slopes are poorly constrained. In general halos with constant density cores (α = 0) provide somewhat better fits, but the majority of our galaxies (~75%) are also consistent with α = 1, as long as the R-band stellar mass-to-light ratios are smaller than about 2. Halos with α = 1.5, however, are ruled out in virtually every case. In order to investigate the robustness of these results we discuss and model several possible causes of systematic errors, including noncircular motions, galaxy inclination, slit width, seeing, and slit alignment errors. Taking the associated uncertainties into account, we conclude that even for the ~25% of the cases where α = 1 seems inconsistent with the rotation curves, we cannot rule out cusp slopes this steep. Inclusion of literature samples similar to the one presented here leads to the same conclusion when the possibility of systematic errors is taken into account. In the ongoing debate on whether the rotation curves of dwarf and low surface brightness galaxies are consistent with predictions for a cold dark matter universe, we argue that our sample and the literature samples discussed in this paper provide insufficient evidence to rule out halos with α = 1. At the same time, we note that none of the galaxies in these samples require halos with steep cusps, as most are equally well or better explained by halos with constant density cores.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/5bbb852a31b16faa17ab123ed1f68ca1ec21368f

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Atomic and Molecular Physics, and Optics

In Instrumentation

Citations in the corpus

NIHAO – IV: core creation and destruction in dark matter density profiles across cosmic time (2015, background): “…split in three groups, the grey symbols areresults from dwarf and Low Surface Brightness (LSB) galaxies (de Blok et al. 2001; de Blok & Bosma 2002; Swaters et al. 2003), cyan filled squares are the results from the THINGS survey (Oh et al. 2011a), while open blue squares with error-bars are the…”
The impact of baryonic physics on the structure of dark matter haloes: the view from the FIRE cosmological simulations (2015, background): “Examples include warm dark matter (WDM), whose free streaming can suppress the small scale structure (Abazajian 2006; Dunstan et al. 2011; Lovell et al. 2012) and self-interacting dark matter (SIDM) whose interaction can substantially affect the central density profile of halos (e.g. Yoshida et al. ”
NGC 3741: the dark halo profile from the most extended rotation curve (2006, background): “…rotation curves of dwarf galaxies (e.g. Borriello & Salucci 2001; van den Bosch & Swaters 2001; de Blok, McGaugh & Rubin 2001; de Blok & Bosma 2002; Swaters et al. 2003; Weldrake, de Blok & Walter 2003; Gentile et al. 2005; Simon et al. 2005), in particular to test whether the density profile…”
The Core-Cusp Problem (2009, background): “Swaters et al. (2003a) also present extensive modeling of high-resolution long-slit Hα rotation curves, and show that while their data are consistent withα = 0 cores, steeper slopes cannot be ruled out.”
The Sloan Lens ACS Survey. VI. Discovery and Analysis of a Double Einstein Ring (2008, background): “Extended mass profiles of galaxies provide evidence for dark matter either using rotation curves (e.g. Rubin et al. 1980; van Albada et al. 1985; Swaters et al. 2003), weak lensing (e.g. Brainerd et al. 1996; Hoekstra et al. 2004; Sheldon et al. 2004; Mandelbaum et al. 2006), or dynamics of…”
HIGH-RESOLUTION DARK MATTER DENSITY PROFILES OF THINGS DWARF GALAXIES: CORRECTING FOR NONCIRCULAR MOTIONS (2008, methodology): “…effects, such as beam smearing, pointing offsets, and noncircular motions, could affect the measured inner slope of the density profile, and may therefore “hide” the signatures of cusps in the central parts of galaxies (van den Bosch et al. 2000; Swaters et al. 2003; Hayashi & Navarro 2006).”
THE CENTRAL SLOPE OF DARK MATTER CORES IN DWARF GALAXIES: SIMULATIONS VERSUS THINGS (2010, background): “…as beam smearing, center offset and non-circular motions, which may play a role in hiding central cusps (Blais-Ouellette et al. 1999; van den Bosch et al. 2000; Bolatto et al. 2002; Swaters et al. 2003; Simon et al. 2003; Rhee et al. 2004; Gentile et al. 2005; Spekkens et al. 2005; Oh et al. 2008).”
High-Resolution Measurements of the Halos of Four Dark Matter-Dominated Galaxies: Deviations from a Universal Density Profile (2004, methodology): “Despite our disagreement on the value of the mean slope, we agree with other recent studies that found that dark matter density profiles span a wide range of slopes (e.g., de Blok et al. 2003; Swaters et al. 2003).”
The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, background): “…use a cored one, which is supported by observations of normal low brightness and dwarf galaxies (Blais-Ouellette et al. 2001; de Blok & Bosma 2002; Swaters et al. 2003; Gentile et al. 2004, 2005; Spekkens et al. 2005; de Blok 2005; de Blok et al. 2008; Spano et al. 2008; Walker & Peñarrubia…”
The dependence of dark matter profiles on the stellar-to-halo mass ratio: a prediction for cusps versus cores (2013, methodology): “Simulated DM haloes modeled with an Einasto (Einasto 1965) profile have a inner slope of−0.7 (Graham et al. 2006): this value is closer to what observed in real galaxies (Swaters et al. 2003), yet not sufficient to solve the discrepancy (de Blok et al. 2003).”
Concentration, spin and shape of dark matter haloes as a function of the cosmological model: WMAP1, WMAP3 and WMAP5 results (2008, background): “This may help to reconcile the conflict between the concentration parameters inferred from the rotation curves of dwarf and low surface brightness (LSB) galaxies (de Blok, McGaugh & Rubin 2001; Swaters et al. 2003) and those predicted from the ΛCDM scenario.”