The Sizes of Quasar Host Galaxies in the Hyper Suprime-Cam Subaru Strategic Program

Junyao Li, John D. Silverman, Xuheng Ding, Michael A. Strauss, Andy Goulding, Simon Birrer, Hassen M. Yesuf, Yongquan Xue, Lalitwadee Kawinwanichakij, Yoshiki Matsuoka, Yoshiki Toba, Tohru Nagao, Malte Schramm, Kohei Inayoshi

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


The relationship between quasars and their host galaxies provides clues on how supermassive black holes (SMBHs) and massive galaxies are jointly assembled. To elucidate this connection, we measure the structural and photometric properties of the host galaxies of ∼5000 Sloan Digital Sky Survey quasars at 0.2 < z < 1 using five-band (grizy) optical imaging from the Hyper Suprime-Cam Subaru Strategic Program. An automated analysis tool is used to forward-model the blended emission of the quasar as characterized by the point-spread function and the underlying host galaxy as a two-dimensional Sérsic profile. We find that quasars are preferentially hosted by massive star-forming galaxies with disklike light profiles. Furthermore, the size distribution of quasar hosts is broad at a given stellar mass and the average values exhibit a size-stellar mass relation as seen with inactive galaxies. In contrast, the sizes of quasar hosts are more compact than those of inactive star-forming galaxies on average, but not as compact as those of quiescent galaxies of similar stellar masses. This is true irrespective of quasar properties, including the bolometric luminosity, Eddington ratio, and black hole mass. These results are consistent with a scenario in which galaxies are concurrently fueling an SMBH and building their stellar bulge from a centrally concentrated gas reservoir. Alternatively, quasar hosts may be experiencing a compaction process in which stars from the disk and inflowing gas are responsible for growing the bulge. In addition, we confirm that the host galaxies of type 1 quasars have a bias of being closer to face-on systems, suggesting that galactic-scale dust can contribute to obscuring the broad-line region.

Original languageEnglish (US)
Article number22
JournalAstrophysical Journal
Issue number1
StatePublished - Sep 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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