@article{202936687b5f4fb78a2783dddb6bf9d6,
title = "Subaru high-Z exploration of Low-luminosity quasars (ShellQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies",
abstract = "We present ALMA [C II] line and far-infrared (FIR) continuum observations of three z > 6 low-luminosity quasars (M1450 > –25 mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The [C II] line was detected in all three targets with luminosities of (2.4–9.5) × 108 L⊙, about one order of magnitude smaller than optically luminous (M1450 ≲ –25 mag) quasars. The FIR continuum luminosities range from < 9 × 1010 L⊙ (3 σ limit) to ∼2 × 1012 L⊙, indicating a wide range in star formation rates in these galaxies. Most of the HSC quasars studied thus far show [C II]/FIR luminosity ratios similar to local star-forming galaxies. Using the [C II]-based dynamical mass (Mdyn) as a surrogate for bulge stellar mass (Mbulge), we find that a significant fraction of low-luminosity quasars are located on or even below the local MBH–Mbulge relation, particularly at the massive end of the galaxy mass distribution. In contrast, previous studies of optically luminous quasars have found that black holes are overmassive relative to the local relation. Given the low luminosities of our targets, we are exploring the nature of the early co-evolution of supermassive black holes and their hosts in a less biased way. Almost all of the quasars presented in this work are growing their black hole mass at a much higher pace at z ∼ 6 than the parallel growth model, in which supermassive black holes and their hosts grow simultaneously to match the local MBH–Mbulge relation at all redshifts. As the low-luminosity quasars appear to realize the local co-evolutionary relation even at z ∼ 6, they should have experienced vigorous starbursts prior to the currently observed quasar phase to catch up with the relation.",
keywords = "Galaxies: ISM, Galaxies: high-redshift, Galaxies: starburst, Quasars: general, Quasars: supermassive black holes",
author = "Takuma Izumi and Masafusa Onoue and Yoshiki Matsuoka and Tohru Nagao and Strauss, {Michael A.} and Masatoshi Imanishi and Nobunari Kashikawa and Seiji Fujimoto and Kotaro Kohno and Yoshiki Toba and Hideki Umehata and Tomotsugu Goto and Yoshihiro Ueda and Hikari Shirakata and Silverman, {John D.} and Greene, {Jenny E.} and Yuichi Harikane and Yasuhiro Hashimoto and Soh Ikarashi and Daisuke Iono and Kazushi Iwasawa and Lee, {Chien Hsiu} and Takeo Minezaki and Kouichiro Nakanishi and Yoichi Tamura and Tang, {Ji Jia} and Akio Taniguchi",
note = "Funding Information: Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen{\textquoteright}s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under Grant No. AST-1238877, the University of Maryland, and Eotvos Lorand University (ELTE). Funding Information: The Hyper Suprime-Cam (HSC) collaboration includes the astronomical communities of Japan and Taiwan, and Princeton University. The HSC instrumentation and software were developed by the National Astronomical Observatory of Japan (NAOJ), the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), the University of Tokyo, the High Energy Accelerator Research Organization (KEK), the Academia Sinica Institute for Astronomy and Astrophysics in Taiwan (ASIAA), and Princeton University. Funding was contributed by the FIRST program from the Japanese Cabinet Office, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the Japan Society for the Promotion of Science (JSPS), the Japan Science and Technology Agency (JST), the Toray Science Foundation, NAOJ, Kavli IPMU, KEK, ASIAA, and Princeton University. Funding Information: T.I., M.I., Y.M., N.K., T.N., K.K., and Y.T. are supported by Japan Society for the Promotion of Science (JSPS) KAKENHI grant numbers JP17K14247, JP15K05030, JP17H04830, JP15H03645, JP17H01114, and JP17H06130, respectively. Y.M. is also supported by the Mitsubishi Foundation grant no. 30140. T.G. acknowledges the support by the Ministry of Science and Technology of Taiwan through grant 105-2112-M-007-003-MY3. T.I. is supported by the ALMA Japan Research Grant of NAOJ Chile Observatory, NAOJ-ALMA-217. Publisher Copyright: {\textcopyright} The Author(s) 2019. Published by Oxford University Press on behalf of the Astronomical Society of Japan. All rights reserved.",
year = "2019",
month = dec,
day = "1",
doi = "10.1093/pasj/psz096",
language = "English (US)",
volume = "71",
journal = "Publications of the Astronomical Society of Japan",
issn = "0004-6264",
publisher = "Astronomical Society of Japan",
number = "6",
}