An X-ray-optical study of the complex dynamics of the core of the massive intermediate-redshift cluster MACSJ0717.5 3745 - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




An X-ray-optical study of the complex dynamics of the core of the massive intermediate-redshift cluster MACSJ0717.5 3745 - Astrophysics > Cosmology and Nongalactic Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: Using CHANDRA, we investigate the spatial temperature distribution of theintracluster medium ICM within 700 kpc of the center of the massive mergingcluster MACSJ0717.5+3745 at z=0.55. Combining the X-ray evidence withinformation about the distribution and velocities of the cluster galaxies nearthe core provides us with a snapshot of the three-dimensional geometry anddynamics of one of the most complex cluster studied to date. We findMACSJ0717.5+3745 to be an active triple merger with ICM temperatures exceeding20 keV. Although radial velocity information and X-ray-optical offsets indicatethat all three mergers proceed along distinctly different directions, thepartial alignment of the merger axes points to a common origin in thelarge-scale filament south-east of the cluster core. Clear decrements in theICM temperature observed near two of these subclusters identify the respectiveX-ray surface brightness peaks as remnants of cool cores; the compactness andlow temperature of 5.7 keV of one of these features suggest that the respectivemerger, a high-velocity collision at 3,000 km-s, is still in its very earlystages. Looking beyond the triple merger, we find the large-scale filament tonot only provide a spatial as well as temporal arrow for the interpretation ofthe dynamics of the merger events near the cluster core; we also findtantalizing, if circumstantial, evidence for direct, large-scale heating of theICM by contiguous infall of low-density gas from the filament.



Autor: Cheng-Jiun Ma, Harald Ebeling, Elizabeth Barrett

Fuente: https://arxiv.org/



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