THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. II. SEPARATING LUMINOUS AND DARK MATTER IN CLUSTER CORES

By A. Newman, T. Treu, Richard S. Ellis, D. Sand. 2012

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We present stellar and dark matter (DM) density profiles for a sample of seven massive, relaxed galaxy clusters derived from strong and weak gravitational lensing and resolved stellar kinematic observations within the centrally located brightest cluster galaxies (BCGs). In Paper I of the series, we demonstrated that the total density profile derived from these data, which span three decades in radius, is consistent with numerical DM-only simulations at radii ≳ 5–10 kpc, despite the significant contribution of stellar material in the core. Here, we decompose the inner mass profiles of these clusters into stellar and dark components. Parameterizing the DM density profile as a power law ρDM∝r−β on small scales, we find a mean slope 〈β〉 = 0.50 ± 0.10(random)+0.14−0.13(systematic). Alternatively, cored Navarro–Frenk–White (NFW) profiles with 〈log rcore/kpc〉 = 1.14 ± 0.13+0.14−0.22 provide an equally good description. These density profiles are significantly shallower than canonical NFW models at radii ≲ 30 kpc, comparable to the effective radii of the BCGs. The inner DM profile is correlated with the distribution of stars in the BCG, suggesting a connection between the inner halo and the assembly of stars in the central galaxy. The stellar mass-to-light ratio inferred from lensing and stellar dynamics is consistent with that inferred using stellar population synthesis models if a Salpeter initial mass function is adopted. We compare these results to theories describing the interaction between baryons and DM in cluster cores, including adiabatic contraction models and the possible effects of galaxy mergers and active galactic nucleus feedback, and evaluate possible signatures of alternative DM candidates.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/7847aa40ce98a866663739a749a778902569cd0f

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Citations in the corpus

Self-Interacting Dark Matter from a Non-Abelian Hidden Sector (2014, background): “To address these concerns with ΛCDM, there are a few generic possibilities to consider [54]: adding feedback from baryons in simulations [55–57], warm dark matter (WDM) [58–60], and selfinteracting dark matter [61–63].”
HUBBLE SPACE TELESCOPE COMBINED STRONG AND WEAK LENSING ANALYSIS OF THE CLASH SAMPLE: MASS AND MAGNIFICATION MODELS AND SYSTEMATIC UNCERTAINTIES (2014, methodology): “Three secure multipleimage systems are known for this cluster, and we follow here the SL constraints (including revised redshifts) as given in Newman et al. (2013b).”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “These profiles can be measeured directly using strong gravitational lensing (e.g., Sand et al. 2008; Newman et al. 2013).”
The impact of baryonic physics on the structure of dark matter haloes: the view from the FIRE cosmological simulations (2015, background): “Nevertheless, stellar kinematics and strong lensing do suggest cores in galaxy clusters with α ∼ −0.5 (Newman et al. 2013b,a).”