104 citations · 1.1k across the 42 of their papers we have counts for
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Final results for mapping the Milky Way's stellar halo with blue horizontal-branch stars selected from the Subaru Hyper Supreme-Cam Survey
Tetsuya Fukushima, Masashi Chiba, Mikito Tanaka +7
We select blue-horizontal branch stars (BHBs) from the internal data release of the Hyper Suprime-Cam Subaru Strategic Program to reveal the global structure of the Milky Way (MW)…
EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of Extremely-Metal Poor Galaxies
Yi Xu, Masami Ouchi, Yuki Isobe +49
We present demography of the dynamics and gas-mass fraction of 33 extremely metal-poor galaxies (EMPGs) with metallicities of and low stellar masses of $10^4-…
Study of structural parameters and systemic proper motion of Sextans dwarf spheroidal galaxy with Subaru Hyper Suprime-Cam data
Akira Tokiwa, Masahiro Takada, Tian Qiu +4
We use the Subaru Hyper Suprime-Cam (HSC) data to study structural parameters and systemic proper motion of the Sextans dwarf spheroidal galaxy at the heliocentric distance of 86 k…
The Missing Satellite Problem Outside of the Local Group. II. Statistical Properties of Satellites of Milky Way-like Galaxies
Masashi Nashimoto, Masayuki Tanaka, Masashi Chiba +3
We present a new observation of satellite galaxies around seven Milky Way (MW)-like galaxies located outside of the Local Group (LG) using Subaru/Hyper Suprime-Cam imaging data to…
Dark matter halo properties of the Galactic dwarf satellites: implication for chemo-dynamical evolution of the satellites and a challenge to CDM
Kohei Hayashi, Yutaka Hirai, Masashi Chiba +1
Elucidating dark matter density profiles in the Galactic dwarf satellites is essential to understanding not only the quintessence of dark matter, but also the evolution of the sate…
Constraining Self-Interacting Dark Matter with Dwarf Spheroidal Galaxies and High-resolution Cosmological -body Simulations
Toshihiro Ebisu, Tomoaki Ishiyama, Kohei Hayashi
We study the density structures of dark matter subhalos for both cold dark matter and self-interacting dark matter models using high-resolution cosmological -body simulations. W…
Interstellar Gas Heating by Primordial Black Holes
Volodymyr Takhistov, Philip Lu, Graciela B. Gelmini +3
Interstellar gas heating is a powerful cosmology-independent observable for exploring the parameter space of primordial black holes (PBHs) formed in the early Universe that could c…
Diversity of dark matter density profiles in the Galactic dwarf spheroidal satellites
Kohei Hayashi, Masashi Chiba, Tomoaki Ishiyama
The core-cusp problem is one of the controversial issues in the standard paradigm of cold dark matter (CDM) theory. However, under the assumption of conventional spherical s…
Formation of massive globular clusters with dark matter and its implication on dark matter annihilation
Henriette Wirth, Kenji Bekki, Kohei Hayashi
Recent observational studies of -ray emission from massive globular clusters (GCs) have revealed possible evidence of dark matter (DM) annihilation within GCs. It is, however, s…
EMPRESS. III. Morphology, Stellar Population, and Dynamics of Extremely Metal Poor Galaxies (EMPGs): Are EMPGs Local Analogs of High- Young Galaxies?
Yuki Isobe, Masami Ouchi, Takashi Kojima +16
We present the morphology and stellar population of 27 extremely metal poor galaxies (EMPGs) at with metallicities of 0.01--0.1 Z. We conduct multi-component sur…
N-body self-consistent stars-halo modeling of the Fornax dwarf galaxy
Galina Shchelkanova, Kohei Hayashi, Sergei Blinnikov
We present nearly self-consistent stellar-halo models of the Fornax dwarf spheroidal galaxy associated with the Milky Way galaxy. Such galaxies are dominated by dark matter and hav…
-factor estimation of Draco, Sculptor and Ursa Minor dwarf spheroidal galaxies with the member/foreground mixture model
Shun-ichi Horigome, Kohei Hayashi, Masahiro Ibe +3
Dwarf spheroidal galaxies (dSphs) are promising targets of indirect detection experiments searching for dark matter (DM) at present universe. Toward robust prediction for the amoun…
Boötes IV: A New Milky Way Satellite Discovered in the Subaru Hyper Suprime-Cam Survey and Implications for the Missing Satellite Problem
Daisuke Homma, Masashi Chiba, Yutaka Komiyama +13
We report on the discovery of a new Milky Way (MW) satellite in Boötes based on data from the on-going Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP). This satellite, named…
Effects of mass models on dynamical mass estimate: the case of ultra diffuse galaxy NGC1052-DF2
Kohei Hayashi, Shigeki Inoue
NGC1052-DF2 was recently discovered as the dark-matter deficient galaxy claimed by van Dokkum et al. (2018a, vD18). However, large uncertainties on its dynamical mass estimate have…
The Missing Satellite Problem Outside of the Local Group: I -- Pilot Observation
Masayuki Tanaka, Masashi Chiba, Kohei Hayashi +5
We present results from a pilot observation of nearby (~20 Mpc) galaxies with mass similar to that of the Milky Way (MW) to address the missing satellite problem. This is the first…
Dark halo structure in the Carina dwarf spheroidal galaxy: joint analysis of multiple stellar components
Kohei Hayashi, Michele Fabrizio, Ewa L. Łokas +4
Photometric and spectroscopic observations of the Carina dSph revealed that this galaxy contains two dominant stellar populations of different age and kinematics. The co-existence…
Stellar Stream and Halo Structure in the Andromeda Galaxy From a Subaru/Hyper Suprime-Cam Survey
Yutaka Komiyama, Masashi Chiba, Mikito Tanaka +13
We present wide and deep photometry of the northwest part of the halo of the Andromeda galaxy (M31) using Hyper Suprime-Cam on the Subaru Telescope. The survey covers 9.2 deg…
Foreground effect on the -factor estimation of ultra-faint dwarf spheroidal galaxies
Koji Ichikawa, Shun-ichi Horigome, Miho N. Ishigaki +4
Dwarf spheroidal galaxies (dSphs) are promising targets for the gamma-ray dark matter (DM) search. In particular, DM annihilation signal is expected to be strong in some of the rec…
Searches for New Milky Way Satellites from the First Two Years of Data of the Subaru/Hyper Suprime-Cam Survey: Discovery of Cetus~III
Daisuke Homma, Masashi Chiba, Sakurako Okamoto +12
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) ~d…
Universal dark halo scaling relation for the dwarf spheroidal satellites
Kohei Hayashi, Tomoaki Ishiyama, Go Ogiya +3
Motivated by a recently found interesting property of the dark halo surface density within a radius, , giving the maximum circular velocity, , we investig…
Foreground effect on the -factor estimation of classical dwarf spheroidal galaxies
Koji Ichikawa, Miho N. Ishigaki, Shigeki Matsumoto +4
The gamma-ray observation of the dwarf spheroidal galaxies (dSphs) is a promising approach to search for the dark matter annihilation (or decay) signal. The dSphs are the nearby sa…
Dark matter annihilation and decay from non-spherical dark halos in the Galactic dwarf satellites
Kohei Hayashi, Koji Ichikawa, Shigeki Matsumoto +3
The dwarf spheroidal galaxies (dSphs) in the Milky Way are the primary targets in the indirect searches for particle dark matter. To set robust constraints on candidate of dark mat…
Structural properties of non-spherical dark halos in Milky Way and Andromeda dwarf spheroidal galaxies
Kohei Hayashi, Masashi Chiba
We investigate the non-spherical density structure of dark halos of the dwarf spheroidal (dSph) galaxies in the Milky Way and Andromeda galaxies based on revised axisymmetric mass…
A common surface-density scale for the Milky Way and Andromeda dwarf satellites as a constraint on dark matter models
Kohei Hayashi, Masashi Chiba
In an attempt to place an explicit constraint on dark matter models, we define and estimate a mean surface density of a dark halo within a radius of maximum circular velocity, whic…