分类： 天文学 >> 天文学 提交时间： 2023-02-19
Dan Hu
Haiguang Xu
Zhenghao Zhu
Chenxi Shan
Yongkai Zhu
Shida Fan
Yuanyuan Zhao
Chengze Liu
Hoongwah Siew
Zhongli Zhang
Liyi Gu
Melanie Johnston-Hollitt
Xi Kang
Qinghua Tan
Jiang Chang
Xiang-ping Wu
摘要： We present a new study of the merger dynamics of Abell~1775 by analyzing the high-quality Chandra and XMM-Newton archival data. We confirm/identify an arc-shaped edge (i.e., the head) at $\sim48$~kpc west of the X-ray peak, a split cold gas tail that extends eastward to $\sim163$~kpc, and a plume of spiral-like X-ray excess (within about $81-324$~kpc northeast of the cluster core) that connects to the end of the tail. The head, across which the projected gas temperature rises outward from $3.39_{-0.18}^{+0.28}$~keV to $5.30_{-0.43}^{+0.54}$~keV, is found to be a cold front with a Mach number of $\mathcal{M}\sim0.79$. Along the surfaces of the cold front and tail, typical KHI features (noses and wings, etc.) are found and are used to constrain the upper limit of the magnetic field ($\sim11.2~\mu$G) and the viscosity suppression factor ($\sim0.01$). Combining optical and radio evidence we propose a two-body merger (instead of systematic motion in a large-scale gas environment) scenario and have carried out idealized hydrodynamic simulations to verify it. We find that the observed X-ray emission and temperature distributions can be best reproduced with a merger mass ratio of 5 after the first pericentric passage. The NAT radio galaxy is thus more likely to be a single galaxy falling into the cluster center at a relative velocity of 2800~$\rm km~s^{-1}$, a speed constrained by its radio morphology. The infalling subcluster is expected to have a relatively low gas content, because only a gas-poor subcluster can cause central-only disturbances as observed in such an off-axis merger.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jiajun Zhang
Pablo Motta
Camila P. Novaes
Filipe B. Abdalla
Andre A. Costa
Bin Wang
Zhenghao Zhu
Chenxi Shan
Haiguang Xu
Elcio Abdalla
Luciano Barosi
Francisco A. Brito
Amilcar Queiroz
Thyrso Villela
Carlos A. Wuensche
Elisa G. M. Ferreira
Karin S. F. Fornazier
Alessandro Marins
Larissa Santos
Marcelo Vargas dos Santos
摘要： BINGO (Baryon Acoustic Oscillations from Integrated Neutral Gas Observations.) is a radio telescope designed to survey from 980 MHz to 1260 MHz, observe the neutral Hydrogen (HI) 21-cm line and detect BAO (Baryon Acoustic Oscillation) signal with Intensity Mapping technique. Here we present our method to generate mock maps of the 21-cm Intensity Mapping signal covering the BINGO frequency range and related test results. (Abridged)
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