@article{5ec1e60e567f4c29b21e14ced86d298a,
title = "Searches for new Milky Way satellites from the first two years of data of the Subaru/Hyper Suprime-Cam survey: Discovery of Cetus III",
abstract = "We present the results from a search for new Milky Way (MW) satellites from the first two years of data from the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) ∼300 deg2 and report the discovery of a highly compelling ultra-faint dwarf galaxy candidate in Cetus. This is the second ultra-faint dwarf we have discovered after Virgo I reported in our previous paper. This satellite, Cetus III, has been identified as a statistically significant (10.7 σ) spatial overdensity of star-like objects, which are selected from a relevant isochrone filter designed for a metal-poor and old stellar population. This stellar system is located at a heliocentric distance of 251-11+24 kpc with a most likely absolute magnitude of MV = -2.4 ± 0.6mag estimated from a Monte Carlo analysis. Cetus III is extended with a half-light radius of rh = 90-17+42 pc, suggesting that this is a faint dwarf satellite in the MW located beyond the detection limit of the Sloan Digital Sky Survey. Further spectroscopic studies are needed to assess the nature of this stellar system. We also revisit and update the parameters for Virgo I, finding MV = -0.33-0.87+0.75 mag and rh = 47-13+19 pc. Using simulations of Σ-dominated cold dark matter models, we predict that we should find one or two new MW satellites from ∼300 deg2 HSC-SSP data, in rough agreement with the discovery rate so far. The further survey and completion of HSC-SSP over ∼1400 deg2 will provide robust insights into the missing satellites problem.",
keywords = "Dwarf-galaxies, Galaxies, Individual (Cetus III, Virgo I)-Local Group",
author = "Daisuke Homma and Masashi Chiba and Sakurako Okamoto and Yutaka Komiyama and Masayuki Tanaka and Mikito Tanaka and Ishigaki, {Miho N.} and Kohei Hayashi and Nobuo Arimoto and Garmilla, {Jos{\'e} A.} and Lupton, {Robert H.} and Strauss, {Michael A.} and Satoshi Miyazaki and Wang, {Shiang Yu} and Hitoshi Murayama",
note = "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: This work is based on data collected at the Subaru Telescope and retrieved from the HSC data archive system, which is operated by the Subaru Telescope and Astronomy Data Center at the National Astronomical Observatory of Japan. MC acknowledges support in part from MEXT Grants-in-Aid for Scientific Research on Innovative Areas (Nos. 15H05889, 16H01086). Funding Information: The Pan-STARRS1 Surveys (PS1) have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, 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) and the Los Alamos National Laboratory. Publisher Copyright: {\textcopyright} The Author 2017. Published by Oxford University Press on behalf of the Astronomical Society of Japan. All rights reserved.",
year = "2018",
month = jan,
day = "1",
doi = "10.1093/pasj/psx050",
language = "English",
volume = "70",
journal = "Publications of the Astronomical Society of Japan",
issn = "0004-6264",
publisher = "Astronomical Society of Japan",
number = "Special Issue 1",
}