TY - JOUR
T1 - Stellar Stream and Halo Structure in the Andromeda Galaxy from a Subaru/Hyper Suprime-Cam Survey
AU - Komiyama, Yutaka
AU - Chiba, Masashi
AU - Tanaka, Mikito
AU - Tanaka, Masayuki
AU - Kirihara, Takanobu
AU - Miki, Yohei
AU - Mori, Masao
AU - Lupton, Robert H.
AU - Guhathakurta, Puragra
AU - Kalirai, Jason S.
AU - Gilbert, Karoline
AU - Kirby, Evan
AU - Lee, Myun Gyoon
AU - Jang, In Sung
AU - Sharma, Sanjib
AU - Hayashi, Kohei
N1 - Funding Information:
This work is supported in part by the JSPS Grant-in-Aid for Scientific Research (No. JP25287062, JP15K05037, JP25800098, JP25400222, and JP17H01101), MEXT Grant-in-Aid for Scientific Research on Innovative Areas (No. JP15H05892, JP16H01090 for K.H., JP16H01086 for M.C.), and Grant-in-Aid for JSPS Fellows (TK 26.348). P.G. was supported by NSF grant AST-1412648. M.G.L. and I.S.J. were supported by the National Research Foundation (NRF) grant funded by the Korea Government (NRF-2017R1A2B4004632).
Funding Information:
The 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), Japan Science and Technology Agency (JST), the Toray Science Foundation, NAOJ, Kavli IPMU, KEK, ASIAA, and Princeton University. This paper makes use of software developed for the Large Synoptic Survey Telescope. We thank the LSST Project for making their code freely available. The Pan-STARRS1 (PS1) Surveys 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 and the Max Planck Institute for Extraterrestrial Physics, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen’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).
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.
PY - 2018/1/20
Y1 - 2018/1/20
N2 - We present wide and deep photometry of the northwestern part of the halo of the Andromeda galaxy (M31) using Hyper Suprime-Cam on the Subaru Telescope. The survey covers a 9.2 deg2 field in the g, i, and NB515 bands and shows a clear red giant branch (RGB) of M31's halo stars and a pronounced red clump (RC) feature. The spatial distribution of RC stars shows a prominent stream feature, the Northwestern (NW) Stream, and a diffuse substructure in the southern part of our survey field. We estimate the distances based on the RC method and obtain = 24.63 ± 0.191 (random) ± 0.057 (systematic) and 24.29 ± 0.211 (random) ± 0.057 (systematic) mag for the NW Stream and diffuse substructure, respectively, implying that the NW Stream is located behind M31, whereas the diffuse substructure is located in front of it. We also estimate line-of-sight distances along the NW Stream and find that the southern part of the stream is ∼20 kpc closer to us relative to the northern part. The distance to the NW Stream inferred from the isochrone fitting to the color-magnitude diagram favors the RC-based distance, but the tip of the RGB (TRGB)-based distance estimated for NB515-selected RGB stars does not agree with it. The surface number density distribution of RC stars across the NW Stream is found to be approximately Gaussian with an FWHM of ∼25 arcmin (5.7 kpc), with a slight skew to the southwest side. That along the NW Stream shows a complicated structure, including variations in number density and a significant gap in the stream.
AB - We present wide and deep photometry of the northwestern part of the halo of the Andromeda galaxy (M31) using Hyper Suprime-Cam on the Subaru Telescope. The survey covers a 9.2 deg2 field in the g, i, and NB515 bands and shows a clear red giant branch (RGB) of M31's halo stars and a pronounced red clump (RC) feature. The spatial distribution of RC stars shows a prominent stream feature, the Northwestern (NW) Stream, and a diffuse substructure in the southern part of our survey field. We estimate the distances based on the RC method and obtain = 24.63 ± 0.191 (random) ± 0.057 (systematic) and 24.29 ± 0.211 (random) ± 0.057 (systematic) mag for the NW Stream and diffuse substructure, respectively, implying that the NW Stream is located behind M31, whereas the diffuse substructure is located in front of it. We also estimate line-of-sight distances along the NW Stream and find that the southern part of the stream is ∼20 kpc closer to us relative to the northern part. The distance to the NW Stream inferred from the isochrone fitting to the color-magnitude diagram favors the RC-based distance, but the tip of the RGB (TRGB)-based distance estimated for NB515-selected RGB stars does not agree with it. The surface number density distribution of RC stars across the NW Stream is found to be approximately Gaussian with an FWHM of ∼25 arcmin (5.7 kpc), with a slight skew to the southwest side. That along the NW Stream shows a complicated structure, including variations in number density and a significant gap in the stream.
KW - galaxies: halos
KW - galaxies: individual (M31)
KW - galaxies: structure
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U2 - 10.3847/1538-4357/aaa129
DO - 10.3847/1538-4357/aaa129
M3 - Article
AN - SCOPUS:85041137061
SN - 0004-637X
VL - 853
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 29
ER -