Mon. Not. R. Astron. Soc., 456, 4475-4487 (2016/March-2)
Central mass profiles of the nearby cool-core galaxy clusters Hydra A and A478.
OKABE N., UMETSU K., TAMURA T., FUJITA Y., TAKIZAWA M., MATSUSHITA K., FUKAZAWA Y., FUTAMASE T., KAWAHARADA M., MIYAZAKI S., MOCHIZUKI Y., NAKAZAWA K., OHASHI T., OTA N., SASAKI T., SATO K. and TAM S.I.
Abstract (from CDS):
We perform a weak-lensing study of the nearby cool-core galaxy clusters, Hydra A (z = 0.0538) and A478 (z = 0.0881), of which the brightest cluster galaxies (BCGs) host the powerful activities of active galactic nuclei (AGNs). For each cluster, the observed tangential shear profile is described well by either a single Navarro-Frenk-White model or a two-component model including the BCG as an unresolved point mass. For A478, we determine the BCG and its host-halo masses from a joint fit to weak-lensing and stellar photometry measurements. We find that the choice of initial mass functions (IMFs) can introduce a factor of 2 uncertainty in the BCG mass, whereas the BCG host-halo mass is constrained well by data. We perform a joint analysis of the weak-lensing and stellar kinematics data available for the Hydra A cluster, which allows us to constrain the central mass profile without assuming specific IMFs. We find that the central mass profile (r < 300 kpc) determined from the joint analysis is in excellent agreement with those from independent measurements, including dynamical masses estimated from the cold gas disc component, X-ray hydrostatic total mass estimates, and the central stellar mass estimated with the Salpeter IMF. The observed dark matter fraction around the BCG for Hydra A is found to be smaller than those predicted by adiabatic contraction models, suggesting the importance of other physical processes, such as AGN feedback and/or dissipationless mergers.
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2016)
gravitational lensing: weak - galaxies: clusters: individual: (Hydra A, A478)
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