Environment of SDSS Quasars at <i>z</i> = 0.4–1.0 Explored by Subaru HSC

Abstract The relationship between quasars and their galaxy environment is important for understanding the evolution of galaxies and supermassive black holes, but it is not fully understood. We perform a wide and deep exploration of the environment of quasars at 0.4 &lt; z &lt; 1.0 using the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) survey. We investigate the environment of the 1912 spectroscopically selected quasars from the Sloan Digital Sky Survey (SDSS), using photometrically selected galaxies from the HSC-SSP data, over an area of 505 deg 2 . The quasar environment is compared to the environment of matched galaxies with similar stellar mass and redshift. We employ the k -nearest neighbor method to define the local galaxy number density for both the quasars and the matched galaxies at a scale of a few hundred kpc. As a result, we find that the number density of galaxies around SDSS quasars is lower than that of the matched galaxies by ∼11%–20%. We also investigate possible correlations between the local galaxy number densities and the quasar properties such as black hole mass ( M BH ) and Eddington ratio ( R Edd ). We find that the number density is weakly correlated with M BH and only marginally with R Edd . The apparent correlation with M BH is likely driven by their common dependence on redshift rather than a direct physical connection, while the marginal trend with R Edd is statistically insignificant. These results suggest that the quasar activity is not triggered by the high number density of surrounding galaxies at the scale of a few hundred kpc.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-10-23
DOI
https://doi.org/10.3847/1538-4357/ae0471
Citations
1
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
1.15

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article

Environment of SDSS Quasars at z = 0.4–1.0 Explored by Subaru HSC

Toshihiro Kawaguchi, Sadman Shariar Ali, Mariko Kubo, Kiyoaki Christopher Omori et al.
1 citations
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
1.15
article

Environment of SDSS Quasars at z = 0.4–1.0 Explored by Subaru HSC

Toshihiro Kawaguchi, Sadman Shariar Ali, Mariko Kubo, Kiyoaki Christopher Omori, Tohru Nagao, Hisakazu Uchiyama, Yoshiki Toba, Kyoko SHIBATA, Yuta Suzuki
article en
1 citations

Abstract

Abstract The relationship between quasars and their galaxy environment is important for understanding the evolution of galaxies and supermassive black holes, but it is not fully understood. We perform a wide and deep exploration of the environment of quasars at 0.4 &lt; z &lt; 1.0 using the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) survey. We investigate the environment of the 1912 spectroscopically selected quasars from the Sloan Digital Sky Survey (SDSS), using photometrically selected galaxies from the HSC-SSP data, over an area of 505 deg 2 . The quasar environment is compared to the environment of matched galaxies with similar stellar mass and redshift. We employ the k -nearest neighbor method to define the local galaxy number density for both the quasars and the matched galaxies at a scale of a few hundred kpc. As a result, we find that the number density of galaxies around SDSS quasars is lower than that of the matched galaxies by ∼11%–20%. We also investigate possible correlations between the local galaxy number densities and the quasar properties such as black hole mass ( M BH ) and Eddington ratio ( R Edd ). We find that the number density is weakly correlated with M BH and only marginally with R Edd . The apparent correlation with M BH is likely driven by their common dependence on redshift rather than a direct physical connection, while the marginal trend with R Edd is statistically insignificant. These results suggest that the quasar activity is not triggered by the high number density of surrounding galaxies at the scale of a few hundred kpc.

The Astrophysical JournalVol. 993(1)
Kagoshima University (JP), Institute of Astronomy and Astrophysics, Academia Sinica (TW), Ritsumeikan University (JP), Tohoku University (JP), Hosei University (JP), Kwansei Gakuin University (JP), National Astronomical Observatory of Japan (JP), University of Toyama (JP), Ehime University (JP), Saint Mary's University (CA)
National Science Foundation, Smithsonian Institution, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, Princeton University, Johns Hopkins University, Space Telescope Science Institute, Queen's University Belfast, Durham University, Ministry of Education, Culture, Sports, Science and Technology, Academia Sinica, Cabinet Office, Government of Japan, Queen's University, Max-Planck-Gesellschaft, National Central University, National Astronomical Observatory of Japan, High Energy Accelerator Research Organization, Eötvös Loránd Tudományegyetem, Max-Planck-Institut für Astronomie, Toray Science Foundation, Smithsonian Astrophysical Observatory, Science Mission Directorate, Japan Society for the Promotion of Science, Japan Science and Technology Agency, Planetary Science Division, Los Alamos National Laboratory
Openalex Percentile: Top 15%
Galaxies: Formation, Evolution, Phenomena
1.15
DOIOpen Access PDFOpenAlex
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