Extreme AGN Feedback and Cool Core Destruction in the X-ray Luminous Galaxy Cluster MACS J1931.8-2634
Steven Ehlert, Steve Allen, Anja von der Linden, Aurora Simionescu, Norbert Werner, Greg Taylor, Gianfranco Gentile, Harald Ebeling, Mark T Allen, Douglas Apple… 展开作者
Steven Ehlert, Steve Allen, Anja von der Linden, Aurora Simionescu, Norbert Werner, Greg Taylor, Gianfranco Gentile, Harald Ebeling, Mark T Allen, Douglas Applegate, Robert Dunn, Andy Fabian, Patrick Kelly, Evan Million, R. Glenn Morris, Jeremy Sanders, Robert Schmidt
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19 pages, 15 figures, 5 tables. Accepted by MNRAS for publication September 30 2010
We report on a deep, multiwavelength study of the galaxy cluster MACS J1931.8-2634 using Chandra X-ray, Subaru optical, and VLA 1.4 GHz radio data. This cluster (z=0.352) harbors one of the most X-ray luminous cool cores yet discovered, with an equivalent mass cooling rate within the central 50 kpc is approximately 700 solar masses/yr. Unique features observed in the central core of MACSJ1931.8-2634 hint to a wealth of past activity that has greatly disrupted the original cool core. We observe a spiral of relatively cool, dense, X-ray emitting gas connected to the cool core, as well as highly elongated intracluster light (ICL) surrounding the cD galaxy. Extended radio emission is observed surrounding the central AGN, elongated in the east-west direction, spatially coincident with X-ray cavities. The power input required to inflate these `bubbles' is estimated from both the X-ray and radio emission to reside between 4 and 14e45 erg/s, putting it among the most powerful jets ever observed. This combination of a powerful AGN outburst and bulk motion of the cool core have resulted in two X-ray bright ridges to form to the north and south of the central AGN at a distance of approximately 25 kpc. The northern ridge has spectral characteristics typical of cool cores and is consistent with being a remnant of the cool core after it was disrupted by the AGN and bulk motions. It is also the site of H-alpha filaments and young stars. The X-ray spectroscopic cooling rate associated with this ridge is approximately 165 solar masses/yr, which agrees with the estimate of the star formation rate from broad-band optical imaging (170 solar masses/yr). MACS J1931.8-2634 appears to harbor one of most profoundly disrupted low entropy cores observed in a cluster, and offers new insights into the survivability of cool cores in the context of hierarchical structure formation.
Cool-Core Destruction in Merging Clusters with AGN Feedback and Radiative Cooling
National Taiwan University（台湾大学）；California Institute of Technology（加州理工学院）；National Tsing Hua University（清华大学）；National Center for Theoretical Sciences（国家理论科学中心）；Harvard-Smithsonian Center for Astrophysics（哈佛-史密松天体物理中心）；University of Modena and Reggio Emilia（摩德纳和雷焦艾米利亚大学）
INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano（意大利国家天体物理研究所米兰空间与宇宙物理学研究所）；Università degli Studi di Milano（米兰大学）；DIFA – Università di Bologna（博洛尼亚大学物理与天体物理系）；Università degli studi di Roma ‘Tor Vergata’（罗马第二大学）；INAF – Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）
Multi-Wavelength Signatures of a Giant Cometary Radio Halo in MACSJ0417-1154
National Centre for Radio Astrophysics, Tata Institute of Fundamental Research（塔塔基础研究所国家射电天体物理中心）；International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（塔塔基础研究所国际理论科学中心）；Dipartimento di Fisica e Astronomia (DIFA), Università di Bologna（博洛尼亚大学物理与天文系）；Istituto Nazionale di Astrofisica – Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF)（意大利国家天体物理研究所空间天体物理与宇宙物理学研究所）
The Megaparsec-scale Gas-sloshing Spiral in the Remnant Cool Core Cluster Abell 1763
本文对红移z = 0.231的大质量星系团Abell 1763进行了多波长研究。对19.6 ks钱德拉存档观测的图像分析显示，在团内介质（ICM）中，团簇范围内的螺旋状表面亮度增强。虽然这样的螺旋被理解为形成具有晃动强冷芯（SCC）的簇，但包括螺旋顶点的气体具有中等熵（$\sim$ 110 keV cm $^{2}$）和冷却时间（$\sim$ 6.8 Gyr），表明在整个螺旋形成过程中发生芯破裂。两个由系统中第二和第三等级的星系主导的子星系团沿着一条平行于主星系团ICM的伸长轴的线。这两个子系统似乎都是沿着先前发现的星系团间的灯丝下降的，并且都被认为是负责启动破坏性核心晃动的扰动者的候选者。动力学分析表明，正在发生的相对径向速度为$\sim$ 1800 km s $^{-1}$。Abell 1763星系团中最明亮的星系团具有高的视向速度（v $_{pec}$ $\sim$ 650 km s $^{-1}$），并拥有一个强大的（P $_{1.4}$ $\sim$ 10 $^{26}$ W Hz $^{-1}$）弯曲双叶射电源，可能是由合并中诱导的相对大体积ICM流形成的。SCC破坏的集群合并模型调用低碰撞参量作为核心转换所需的条件。与此相反，在阿贝尔1763年发生的高角动量事件表明，离轴合并在建立非冷核心集群人口比以前假设的发挥更大的作用。
