We present the first wide-field H-alpha imaging survey around the distant cluster RXJ1716.4+6708 at z=0.81 with a narrow-band filter on MOIRCS/Subaru, down to SFR(Ha)~1Msun/yr. Combining with a wide-field MIR imaging survey with AKARI, we compare the unobscured and obscured star formation activities in the cluster. We find that both H-alpha emitters and MIR galaxies avoid the cluster centre and their spatial distribution is quite similar. Most of the H-alpha emitters show blue colours, but we find some H-alpha emitters on the red sequence. The MIR galaxies tend to be systematically redder than the H-alpha emitters probably due to heavy dust extinction. Interestingly, the red H-alpha emitters and the red MIR galaxies (i.e. dusty red galaxies) are most commonly seen in the medium-density environment such as cluster outskirts, groups and filaments, where optical colours of galaxies change. We also find that A(Ha) exceeds ~3 in extreme cases and that such very dusty galaxies are also located in the medium-density environment. These findings suggest that dusty star formation is triggered in the in-fall region of the cluster, implying a probable link between galaxy transition and dusty star formation. We finally calculate the cluster total SFR and find that the cluster total SFR based on H-alpha alone can be underestimated more than factor ~2 even after 1 mag extinction correction. We suggest that the mass-normalized cluster SFR rapidly declines since z~1 following ~(1+z)^6, although the uncertainty is still large.
A High Spatial Resolution Mid-Infrared Spectroscopic Study of the Nuclei and Star-Forming Regions in Luminous Infrared Galaxies
利用T-ReCS在Gemini South望远镜上对4个亮红外星系（LIRGs）的核和恒星形成区进行了高空间（衍射极限）分辨率（~0.3”）的中红外（MIR）光谱研究。我们调查的空间变化中看到的N-波段光谱的LIRGs的尺度上的~100 pc的功能，这使我们能够分离的AGN发射的恒星形成（SF）。我们比较我们的双子座T-ReCS核和积分光谱的LIRGs与斯皮策IRS。9.7um硅酸盐的吸收特征在LIRGs的核中比在周围区域中弱。这可能是由于要么cluerous或紧凑的环境，中央AGN或年轻，核星暴。我们发现[NeII]光度面密度与LIRG恒星形成区的Pa-α光度面密度紧密直接相关（斜率为1.00+-0.02）。尽管11.3 um PAH特征也显示了Pa-α的趋势，但这并不常见于所有区域。我们还发现[NeII] \Pa -α比率不依赖于Pa-α等效宽度（EW），即，的年龄的电离恒星星族，这表明，在这里探测的尺度上，[NeII]发射线是一个很好的示踪剂的SF活动的LIRGs。另一方面，11.3 um PAH \Pa -α比率随着Pa-α EW值的减小（年龄的增加）而增加，这表明11.3 um PAH特征也可以由比Pa-α发射更老的恒星激发。额外的高空间分辨率的观测是必不可少的调查，在统计的方式，在最小尺度上的本地LIRGs的恒星形成，并最终探测它们是否共享相同的物理性质的高z LIRG…
Physical Properties of Spectroscopically-Confirmed Galaxies at z >= 6. I. Basic Characteristics of the Rest-Frame UV Continuum and Lyman-alpha emission
A JWST Paschen-alpha Calibration of the Radio Luminosity-Star Formation Rate Relation at z~1.3
International Centre for Radio Astronomy Research, Curtin University（国际射电天文研究中心，科廷大学）；Astrophysics, Department of Physics, University of Oxford（牛津大学物理系天体物理学）；Institute for Astronomy, University of Edinburgh（爱丁堡大学天文学研究所）；Department of Physics & Astronomy, University of the Western Cape（西开普大学物理与天文学系）；Department of Astronomy, University of Geneva（日内瓦大学天文学系）；Cosmic Dawn Center (DAWN), Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所宇宙黎明中心）；Department of Physics, University of Bath（巴斯大学物理系）；Instituto de Astrofísíca e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa（里斯本大学理学院空间天体物理与科学研究所）
