We present the NIR luminosity (LF) and stellar mass functions (SMF) of galaxies in the core of the Shapley supercluster at z=0.048, based on new K-band observations in conjunction with B- and R-band photometry and a subsample of ~650 galaxies spectroscopically confirmed supercluster members, allowing to investigate the galaxies down to M_K^*+6 and M=10^8.75 M_sun. For the 3 deg^2 field the K-band LF is described by a Schechter function with M_K^*=-24.96+-0.10 and α=-1.42+-0.03. We investigate the effect of environment by deriving the LF in three regions selected according to the local galaxy density, and observe a significant increase in the faint-end slope going from the high- (α=-1.33) to the low-density (α=-1.49) environments. The SMF is fitted well by a Schechter function with log_10(M^*)=11.16+-0.04 and α=-1.20+-0.02. The SMF of supercluster galaxies is also characterised by an excess of massive galaxies that are associated to the cluster BCGs. While the value of M* depends on environment the slope of the galaxy SMF does not vary with the environment. By comparing our findings with cosmological simulations, we conclude that the environmental dependences of the LF are not primary due to variations in the merging histories, but to processes which are not treated in the semi-analytical models, such as tidal stripping or harassment. In field regions the SMF shows a sharp upturn below M=10^9 M_sun, close to our mass limit, suggesting that the upturns seen in our K-band LFs, but not in the SMF, are due to this dwarf population. The environmental variations seen in the faint-end of the K-band LF suggests that dwarf galaxies, which are easier to strip than their more massive counterparts, are affected by tidal/gas stripping upon entering the supercluster.
Magnetic Fields in the Shapley Supercluster Core with POSSUM: Challenging Model Predictions
Universidad Complutense de Madrid（马德里康普顿斯大学）；Università degli Studi di Bologna（博洛尼亚大学）；INAF – Istituto di Radioastronomia（意大利国家天体物理研究所射电天文研究所）；The University of Chicago（芝加哥大学）；Dunlap Institute for Astronomy and Astrophysics, University of Toronto（多伦多大学邓普勒天文学与天体物理研究所）；The Australian National University（澳大利亚国立大学）；National Research Council Canada, Herzberg Research Centre for Astronomy and Astrophysics（加拿大国家研究委员会赫茨伯格天文学与天体物理研究中心）
Hidden Vela Supercluster Revealed by First Hybrid Redshift & Peculiar Velocity Reconstruction
Université Claude Bernard Lyon 1（里昂第一大学）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天体物理学与天文学研究学院）；Department of Astronomy, University of Cape Town（开普敦大学天文学系）；Centre for Astrophysics & Supercomputing, Swinburne University（斯威本大学天体物理与超级计算中心）；ARC Centre of Excellence for Dark Matter Particle Physics（ARC暗物质粒子物理卓越研究中心）；INAF Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）
Cosmic dance in the Shapley Concentration Core II. The uGMRT-MeerKAT view of filaments in the brightest cluster galaxies and tailed radio galaxies in the A3528 cluster complex
本文利用 uGMRT 和 MeerKAT 射电观测结合 eROSITA X 射线数据，研究沙普利超星系团核心 A3528 复合体，发现最亮团星系周围存在谱指数极陡的弥散射电纤维，并提出小型并合可重新加速射电星系等离子体。
