分类： 天文学 >> 天文学 提交时间： 2023-02-19
Kei Ito
Masayuki Tanaka
Francesco Valentino
Sune Toft
Gabriel Brammer
Katriona M. L. Gould
Olivier Ilbert
Nobunari Kashikawa
Mariko Kubo
Yongming Liang
Henry J. McCracken
John R. Weaver
摘要： Protoclusters of galaxies have been found in the last quarter century. However, most of them have been found through the overdensity of star-forming galaxies, and there had been no known structures identified by multiple spectroscopically confirmed quiescent galaxies at $z>2.5$. In this letter, we report the discovery of an overdense structure of massive quiescent galaxies with the spectroscopic redshift $z=2.77$ in the COSMOS field, QO-1000. We first photometrically identify this structure as a $4.2\sigma$ overdensity with 14 quiescent galaxies in $7\times4\ {\rm pMpc^2}$ from the COSMOS2020 catalog. We then securely confirm the spectroscopic redshifts of 4 quiescent galaxies by detecting multiple Balmer absorption lines with Keck/MOSFIRE. All the spectroscopically confirmed members are massive ($\log{(M_\star/M_\odot)}>11.0$) and located in a narrow redshift range ($2.7668$ times denser than in the general field. In addition, we confirm that they form a red sequence in the $J-K_s$ color. This structure's halo mass is estimated as $\log{(M_{\rm halo}/M_\odot)}>13.2$ from their stellar mass. Similar structures found in the IllustrisTNG simulation are expected to evolve into massive galaxy clusters with $\log{(M_{\rm halo}/M_\odot)}\geq14.8$ at $z=0$. These results suggest that QO-1000 is a more mature protocluster than the other known protoclusters. It is likely in a transition phase between the star-forming protoclusters and the quenched galaxy clusters.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Kohei Ichikawa
Takuji Yamashita
Andrea Merloni
Junyao Li
Teng Liu
Mara Salvato
Masayuki Akiyama
Riccardo Arcodia
Tom Dwelly
Xiaoyang Chen
Masatoshi Imanishi
Kohei Inayoshi
Toshihiro Kawaguchi
Taiki Kawamuro
Mitsuru Kokubo
Yoshiki Matsuoka
Tohru Nagao
Malte Schramm
Hyewon Suh
Masayuki Tanaka
摘要： We construct the eROSITA X-ray catalog of radio galaxies discovered by the
WERGS survey that is made by the cross-matching of the wide-area Subaru/HSC
optical survey and VLA/FIRST 1.4 GHz radio survey. We find 393 eROSITA detected
radio galaxies in the 0.5--2 keV band in the eFEDS field covering 140~deg$^2$.
Thanks to the wide and medium depth eFEDS X-ray survey, the sample contains the
rare and most X-ray luminous radio galaxies above the knee of the X-ray
luminosity function, spanning 4422$. Those obscured
and radio AGN reside in $0.4
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Xiangchong Li
Hironao Miyatake
Wentao Luo
Surhud More
Masamune Oguri
Takashi Hamana
Rachel Mandelbaum
Masato Shirasaki
Masahiro Takada
Robert Armstrong
Arun Kannawadi
Satoshi Takita
Satoshi Miyazaki
Atsushi J. Nishizawa
Andrés A. Plazas Malagón
Michael A. Strauss
Masayuki Tanaka
Naoki Yoshida
摘要： We present the galaxy shear catalog that will be used for the three-year cosmological weak gravitational lensing analyses using data from the Wide layer of the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) Survey. The galaxy shapes are measured from the $i$-band imaging data acquired from 2014 to 2019 and calibrated with image simulations that resemble the observing conditions of the survey based on training galaxy images from the Hubble Space Telescope in the COSMOS region. The catalog covers an area of 433.48 deg$^2$ of the northern sky, split into six fields. The mean $i$-band seeing is 0.59 arcsec. With conservative galaxy selection criteria (e.g., $i$-band magnitude brighter than 24.5), the observed raw galaxy number density is 22.9 arcmin$^{-2}$, and the effective galaxy number density is 19.9 arcmin$^{-2}$. The calibration removes the galaxy property-dependent shear estimation bias to a level: $|\delta m|1$ degree scales and will require mitigation during the inference of cosmological parameters using cosmic shear measurements.
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