Witnessing the Formation of a Brightest Cluster Galaxy in a Nearby X-ray Cluster - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




Witnessing the Formation of a Brightest Cluster Galaxy in a Nearby X-ray Cluster - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: The central dominant galaxies in galaxy clusters constitute the most massiveand luminous galaxies in the Universe. Despite this, the formation of thesebrightest cluster galaxies BCGs and the impact of this on the surroundingcluster environment remain poorly understood. Here we present multi-wavelengthobservations of the nearby poor X-ray cluster MZ 10451, in which both processescan be studied in unprecedented detail. Chandra observations of theintracluster medium ICM in the cluster core, which harbors two opticallybright early-type galaxies in the process of merging, show that the system hasretained a cool core and a central metal excess. This suggests that anymerger-induced ICM heating and mixing remain modest at this stage. Tidallystripped stars seen around either galaxy likely represent an emergingintracluster light component, and the central ICM abundance enhancement mayhave a prominent contribution from in situ enrichment provided by these stars.The smaller of the merging galaxies shows evidence for having retained a hotgas halo, along with tentative evidence for some obscured star formation,suggesting that not all BCG major mergers at low redshift are completelydissipationless. Both galaxies are slightly offset from the peak of the ICMemission, with all three lying on an axis that roughly coincides with thelarge-scale elongation of the ICM. Our data are consistent with a picture inwhich central BCGs are built up by mergers close to the cluster core, bygalaxies infalling on radial orbits aligned with the cosmological filamentsfeeding the cluster.



Author: Jesper Rasmussen, John S. Mulchaey, Lei Bai, Trevor J. Ponman, Somak Raychaudhury, Ali Dariush

Source: https://arxiv.org/







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