Tuesday, May 21, 2013

1305.3926 (S. Ettori et al.)

Cold fronts and metal anisotropies in the X-ray cool core of the galaxy cluster Zw1742+3306    [PDF]

S. Ettori, F. Gastaldello, M. Gitti, E. O'Sullivan, M. Gaspari, F. Brighenti, L. David, A. C. Edge
(Context) In recent years, our understanding of the cool cores of galaxy clusters from a relatively simple place where gas is cooling and flowing toward the center has changed to a very dynamic place, where heating from the central AGN and cooling, as inferred from active star formation, molecular gas and Halpha nebulosity, find an uneasy energetic balance. (Aims) We want to characterize the X-ray properties of the nearby cool-core cluster Zw1742+3306, selected for being bright at X-ray (with a flux greater than 1e-11 erg/s/cm2 in the 0.1-2.4 keV band) and Halpha wavelength (Halpha lumininosity > 1e40 erg/s). (Methods) We use Chandra data to analyze the spatial and spectral properties of the cool core of Zw1742+3306, a galaxy cluster at z=0.0757 which emits in Halpha and presents the Brightest Central Galaxy located in a diffuse X-ray emission with multiple peaks in surface brightness. (Results) We show that the X-ray cool core of the galaxy cluster Zw1742+3306 is thermodynamically very active with evidence of cold fronts and a weak shock in the surface brightness map and of an apparently coherent, elongated structure with metallicity larger by about 50 per cent than the value measured in the surrounding ambient gas. This anisotropic structure has size 280 x 90 kpc2 and is aligned with the cold fronts and with the X-ray emission on larger scales. We suggest that all these peculiarities in the X-ray emission of Zw1742+3306 are either a very fine-tuned output of a sloshing gas in the cluster core or the product of a metal-rich outflow from the central AGN.
View original: http://arxiv.org/abs/1305.3926

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