Measuring the HI-halo mass scaling relation (HIHM) is fundamental to understanding the role of HI in galaxy formation and its connection to structure formation. While direct measurements of the HI mass in haloes are possible using HI-spectral stacking, the reported shape of the relation depends on the techniques used to measure it (e.g. monotonically increasing with mass versus flat, mass-independent). Using a simulated HI and optical survey produced with the SHARK semi-analytic galaxy formation model, we investigate how well different observational techniques can recover the intrinsic, theoretically predicted, HIHM relation. We run a galaxy group finder and mimic the HI stacking procedure adopted by different surveys and find we can reproduce their observationally derived HIHM relation. However, none of the adopted techniques recover the underlying HIHM relation predicted by the simulation. We find that systematic effects in halo mass estimates of galaxy groups modify the inferred shape of the HIHM relation from the intrinsic one in the simulation, while contamination by interloping galaxies, not associated with the groups, contribute to the inferred HI mass of a halo mass bin, when using large velocity windows for stacking. The effect of contamination is maximal at Mvir~10^(12-12.5)Msol. Stacking methods based on summing the HI emission spectra to infer the mean HI mass of galaxies of different properties belonging to a group suffer minimal contamination but are strongly limited by the use of optical counterparts, which miss the contribution of dwarf galaxies. Deep spectroscopic surveys will provide significant improvements by going deeper while maintaining high spectroscopic completeness; for example, the WAVES survey will recover ~52% of the total HI mass of the groups with Mvir~10^(14)Msol compared to ~21% in GAMA.
Unveiling the weak radio quasar population at z $\geq$ 4
我们对以$z\geq4$光学识别的高红移类星体为中心的20厘米射电天空空场微弱图像（FIRST）巡天图进行了图像叠加，以揭示这些活动星系核（AGN）中隐藏的$μ$ Jy射电辐射。$2229$光学鉴定活动星系核全样本的中值叠加程序揭示了一个积分通量密度为52 $~μ$ Jy的未分辨点源，信噪比为$\sim10$。我们共同添加的个人图像中心像素，以估计在$1.4~$ GHz的特征单色无线电功率考虑各种值的无线电频谱指数，揭示了无线电人口与$P_\mathrm{1.4GHz}\sim10^{24}~$ W Hz $^{-1}$。假设所有的射电辐射都来自于宿主星系核区的恒星形成（SF）活动，我们得到了特征恒星形成速率的上限，即$\sim4200~$ M $_\odot~$ yr $^{-1}$。FIRST图像的角分辨率不足以区分SF和AGN在这些红移处的射电辐射起源。然而，从文献中的个别来源的属性的比较表明，一个混合的性质是可能的。未来的甚长基线射电干涉测量观测和超深平方公里阵列巡天可望具有足够的灵敏度来探测和分辨宿主星系的中心$1-10~$ kpc区域，从而区分SF和AGN相关的辐射。
Stacking 21-cm Maps around Lyman-$α$ Emitters during Reionization: Prospects for a Cross-correlation Detection with the Hydrogen Epoch of Reionization Array
MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理与空间研究所）；Department of Physics, Massachusetts Institute of Technology（麻省理工学院物理系）；Department of Physics, The University of Texas at Dallas（德克萨斯大学达拉斯分校物理系）
Unveiling the Sources of X-ray Luminosity in DESI Galaxy Groups: Insights from the SRG/eROSITA All-Sky Survey
Shanghai Jiao Tong University（上海交通大学）；University of Science and Technology of China（中国科学技术大学）；Beijing Normal University（北京师范大学）；Xiamen University（厦门大学）；Zhejiang University（浙江大学）；Durham University（杜伦大学）
Unveiling the mask on the ULIRG-to-QSO transition object [H89]1821+643 at z=0.3: a gas-poor/gas-rich galaxy merger and the implications for CO-based dynamical mass estimates
Atomic hydrogen reservoirs in quiescent galaxies at z = 0.4
Università degli Studi di Padova（帕多瓦大学）；INAF - Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；National Center for Nuclear Research（波兰核研究中心）；SISSA（的里雅斯特高等研究学院）；Université de Genève（日内瓦大学）；Universität Zürich（苏黎世大学）；University of the Western Cape（西开普大学）；University of Cape Town（开普敦大学）；INAF - Istituto di Radioastronomia（意大利国家天体物理研究所射电天文台）
HI Depletion Begins Well Beyond the Virial Radius: A FAST Stacking Study of 36 Galaxy Clusters to 5R200
Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS（中国科学院南美天文中心，国家天文台）；Key Laboratory of Optical Astronomy, NAOC（国家天文台光学天文重点实验室）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Guizhou Radio Astronomical Observatory, Guizhou University（贵州大学贵州天文观测台）；Instituto de Física y Astronomía, Universidad de Valparaíso（瓦尔帕莱索大学物理与天文学研究所）；Millennium Nucleus for Galaxies (MINGAL)（星系千年核（MINGAL））；Universidad Tecnica Federico Santa Maria（费德里科·圣塔玛利亚理工大学）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；Korea Astronomy and Space Science Institute（韩国天文与空间科学研究院）
International Centre for Radio Astronomy Research, The University of Western Australia（西澳大利亚大学国际射电天文研究中心）；Australia Telescope National Facility, CSIRO Space & Astronomy（CSIRO空间与天文学部澳大利亚望远镜国家设施）；Center for Astrophysics | Harvard & Smithsonian（哈佛-史密森尼天体物理中心）
