2023/11/29 by Yoshihisa Suzuki, Suzuki, Yoshihisa, Masashi Chiba +17
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2311.17378
openalex publication_date 2023/11/29 · openalex created_date 2023/12/01 · openalex updated_date 2026/08/01
We analyze the photometric data in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) over ∼ 1,200 deg2 to uncover new halo substructures beyond the distance, D\odot∼ 30 kpc, from the Sun. For this purpose, we develop an isochrone filter for an old, metal-poor stellar system to extract the faint main-sequence stars at a range of distances. With this method, we detect, not only the previously discovered substructures such as the Orphan Stream, but also the new overdensity toward Boötes at about D\odot∼ 60 kpc and the new stream-like feature toward Pisces at around D\odot∼ 60 kpc. It has been suggested that a small-scale overdensity exists in this direction of Pisces (the so-called Pisces Overdensity), but our results show that the overdensity is widely spread with a tidally elongated feature. Combining our results with the ongoing Hyper Suprime-Cam narrow-band survey and the near-future spectroscopic survey with Prime Focus Spectrograph (PFS) will allow us to place strong constraints on the origin of these halo substructures.