Discovery of large-scale diffuse radio emission and of a new galaxy cluster in the surroundings of MACSJ0520.7-1328
G. Macario, H. T. Intema, C. Ferrari, H. Bourdin, S. Giacintucci, T. Venturi, P. Mazzotta, I. Bartalucci, M. Johnston-Hollitt, R. Cassano, D. Dallacasa, G. W. P… 展开作者
G. Macario, H. T. Intema, C. Ferrari, H. Bourdin, S. Giacintucci, T. Venturi, P. Mazzotta, I. Bartalucci, M. Johnston-Hollitt, R. Cassano, D. Dallacasa, G. W. Pratt, R. Kale, S. Brown
备注：
10 pages, 6 Figures, accepted for publication in A&A
We report the discovery of large-scale diffuse radio emission South-East of the galaxy cluster MACS J0520.7-1328, detected through high sensitivity Giant Metrewave Radio Telescope 323 MHz observations. This emission is dominated by an elongated diffuse radio source and surrounded by other features of lower surface brightness. Patches of these faint sources are marginally detected in a 1.4 GHz image obtained through a re-analysis of archival NVSS data. Interestingly, the elongated radio source coincides with a previously unclassified extended X-ray source. We perform a multi-wavelength analysis based on archival infrared, optical and X-ray Chandra data. We find that this source is a low-temperature (~3.6 keV) cluster of galaxies, with indications of a disturbed dynamical state, located at a redshift that is consistent with the one of the main galaxy cluster MACS J0520.7-132 (z=0.336). We suggest that the diffuse radio emission is associated with the non-thermal components in the intracluster and intergalactic medium in and around the newly detected cluster. We are planning deeper multi-wavelength and multi-frequency radio observations to accurately investigate the dynamical scenario of the two clusters and to address more precisely the nature of the complex radio emission.
Discovery of a diffuse optical line emitting halo in the core of the Centaurus cluster of galaxies: Line emission outside the protection of the filaments
The magnetic mayhem in Abell 2199: discovery of synchrotron threads and homogeneous diffuse radio lobes
Durham University（杜伦大学）；University of Minnesota（明尼苏达大学）；INAF - Instituto di Radioastronomia（意大利国家天体物理研究所射电天文研究所）；National Centre for Radio Astrophysics, Tata Institute of Fundamental Research（塔塔基础研究院国家射电天体物理学中心）
On the Source of the Dust Extinction in Type Ia Supernovae and the Discovery of Anomalously Strong Na I Absorption
对32颗Ia型超新星光谱中Na I D 5890、5896和K I 7665、7699星际谱线以及5780埃的弥散星际谱带的高色散观测被用作探测尘埃消光的独立手段。我们发现，尘埃消光的对象，在5780埃的弥漫星际带被检测到的超新星颜色的视觉消光是一致的。这有力地表明，产生灭绝的尘埃主要位于宿主星系的星际介质中，而不是与祖先系统相关的星周物质中。四分之一的超新星显示巨大的Na I柱密度相比，尘埃消光量来自他们的颜色。值得注意的是，所有异常强的Na I D吸收的情况都对应于Sternberg等人（2011）的分类方案中的"蓝移"分布。这一巧合表明，外流的拱星气体是负责至少一些情况下，巨大的钠离子柱密度。两颗具有异常强的Na I D吸收的超新星显示出其颜色所暗示的尘埃消光的K I柱密度基本正常，但这似乎不是一个普遍的特征。总的来说，我们发现最准确的预测个别超新星灭绝是在5780埃的弥漫星际带的等效宽度，并提供了一个经验关系的使用。最后，我们确定的方法产生显着增强的Na丰度的拱星物质在单简并和双简并的情况下的祖系统。
