Publications (28)
Anomalous popularity growth in social tagging ecosystems
Yasuhiro Hashimoto, Mizuki Oka, Takashi Ikegami
In social tagging systems, the diversity of tag vocabulary and the popularity of such tags continue to increase as they are exposed to selection pressure derived from our cognitive…
The Taiwan Extragalactic Astronomical Data Center (TWEA-DC)
Sebastien Foucaud, Yasuhiro Hashimoto
The next generation of telescopes and instruments are facilitating our understanding of the Universe by producing data at a pace that beats all projections, and astronomers today a…
How the nature of web services drives vocabulary creation in social tagging
Koya Sato, Mizuki Oka, Yasuhiro Hashimoto +2
A social tagging system allows users to add arbitrary strings, called "tags", on a shared resource to organize and manage information. The Yule--Simon process, which has shown the…
Open-ended Evolution and a Mechanism of Novelties in Web Services
Takashi Ikegami, Yasuhiro Hashimoto, Mizuki Oka
Analogous to living ecosystems in nature, web services form an artificial ecosystem consisting of many tags and their associated media, such as photographs, movies, and web pages c…
Role of AGNs in the Luminous Infrared Galaxy phase since z ~ 3
Ming-Yi Lin, Yasuhiro Hashimoto, Sebastien Foucaud
In order to understand the interactions between active galactic nuclei (AGN) and star formation during the evolution of galaxies, we investigate 142 galaxies detected in both X-ray…
Self-organization on social media: endo-exo bursts and baseline fluctuations
Mizuki Oka, Yasuhiro Hashimoto, Takashi Ikegami
A salient dynamic property of social media is bursting behavior. In this paper, we study bursting behavior in terms of the temporal relation between a preceding baseline fluctuatio…
BAT AGN Spectroscopic Survey II: X-ray Emission and High Ionization Optical Emission Lines
Simon Berney, Michael Koss, Benny Trakhtenbrot +17
We investigate the relationship between X-ray and optical line emission in 340 nearby AGN selected above 10 keV using Swift BAT. We find a weak correlation between the extinction c…
Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) III. Star formation properties of the host galaxies at studied with ALMA
Takuma Izumi, Masafusa Onoue, Hikari Shirakata +26
We present our ALMA Cycle 4 measurements of the [CII] emission line and the underlying far-infrared (FIR) continuum emission from four optically low-luminosity ($M_{\rm 1450} > -25…
Growth fluctuation in preferential attachment dynamics
Yasuhiro Hashimoto
In the Yule-Simon process, selection of words follows the preferential attachment mechanism, resulting in the power-law growth in the cumulative number of individual word occurrenc…
Robust quantitative measures of cluster X-ray morphology, and comparisons between cluster characteristics
Yasuhiro Hashimoto, Hans Boehringer, J. Patrick Henry +2
To investigate the relationships between dynamical status and other important characteristics of galaxy clusters, we conducted a study of X-ray cluster morphology using a sample of…
XMM-Newton Observation of a Distant X-ray Selected Cluster of Galaxies at z=1.26 with Possible Cluster Interaction
Yasuhiro Hashimoto, Guenther Hasinger, Monique Arnaud +2
We report on the XMM-Newton (XMM) observation of RXJ1053.7+5735, one of the most distant (z = 1.26) X-ray selected clusters of galaxies, which also shows an unusual double-lobed X-…
Suzaku Observations of Active Galactic Nuclei Detected in the Swift/BAT Survey: Discovery of "New Type" of Buried Supermassive Black Holes
Yoshihiro Ueda, Satoshi Eguchi, Yuichi Terashima +6
We present the Suzaku broad band observations of two AGNs detected by the Swift/BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, Swift J0601.9-8636 and Swift…
On the Nature of AX J2049.6+2939 and AX J2050.0+2914
Emi Miyata, Kouji Ohta, Kenichi Torii +4
AX J2049.6+2939 is a compact X-ray source in the vicinity of the southern blow-up region of the Cygnus Loop supernova remnant (Miyata et al. 1998a). This source was the brightest X…
Multiwavelength investigations of co-evolution of bright custer galaxies
Yasuhiro Hashimoto, J. Patrick Henry, Hans Boehringer
We report a systematic multi-wavelength investigation of environments of the brightest cluster galaxies (BCGs), using the X-ray data from the Chandra archive, and optical images ta…
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
Takuma Izumi, Masafusa Onoue, Yoshiki Matsuoka +24
We present ALMA [CII] line and far-infrared (FIR) continuum observations of three low-luminosity quasars () discovered by our Subaru Hyper Suprime-Cam (…
Star Formation in Las Campanas Compact Groups
Sahar S. Allam, Douglas L. Tucker, Huan Lin +1
Compact groups (CGs) of galaxies offer an exceptional laboratory for the study of dense galaxian environments --- where interactions, tidally induced activity, and mergers are expe…
The Galaxy Populations of Double Cluster RX J1053.7+5735 at z=1.13
Yasuhiro Hashimoto, J. Patrick Henry, Guenther Hasinger +3
We present a study of the galaxy population in the cluster RX J1053.7+5735, one of the most distant X-ray selected clusters of galaxies, which also shows an unusual double-lobed X-…
The Influence of Environment on the Star Formation Rates of Galaxies
Yasuhiro Hashimoto, Augustus Oemler, Huan Lin +1
We have used a sample of 15749 galaxies taken from the Las Campanas Redshift Survey to investigate the effects of environment on the rate of star formation (SFR) in galaxies. The s…
Revisiting Disparity from Dual-Pixel Images: Physics-Informed Lightweight Depth Estimation
Teppei Kurita, Yuhi Kondo, Legong Sun +5
In this study, we propose a high-performance disparity (depth) estimation method using dual-pixel (DP) images with few parameters. Conventional end-to-end deep-learning methods hav…
Scattered X-rays in Obscured Active Galactic Nuclei and their Implications for Geometrical Structure and Evolution
Kazuhisa Noguchi, Yuichi Terashima, Yukiko Ishino +4
We construct a new sample of 32 obscured active galactic nuclei (AGNs) selected from the Second XMM-Newton Serendipitous Source Catalogue to investigate their multiwavelength prope…
Abundance Constraints and Direct Redshift Measurement of the Diffuse X-ray Emission from a Distant Cluster of Galaxies
Yasuhiro Hashimoto, Xavier Barcons, Hans Boehringer +4
We report on the XMM-Newton (XMM) observation of RXJ1053.7+5735, one of the most distant X-ray selected clusters of galaxies, which also shows an unusual double-lobed X-ray morphol…
Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) XII. Extended [C II] Structure (Merger or Outflow) in a z = 6.72 Red Quasar
Takuma Izumi, Masafusa Onoue, Yoshiki Matsuoka +31
We present ALMA [C II] 158 m line and far-infrared (FIR) continuum emission observations toward HSC J120505.09000027.9 (J12050000) at with the beam size of $\s…
BAT AGN Spectroscopic Survey I: Spectral Measurements, Derived Quantities, and AGN Demographics
Michael Koss, Benny Trakhtenbrot, Claudio Ricci +20
We present the first catalog and data release of the Swift-BAT AGN Spectroscopic Survey (BASS). We analyze optical spectra of the majority of AGN (77%, 641/836) detected based on t…
Alignment of Galaxies and Clusters
Yasuhiro Hashimoto, J. Patrick Henry, Hans Boehringer
We investigated the influence of environment on cluster galaxies by examining the alignment of the brightest cluster galaxy (BCG) position angle with respect to the host cluster X-…
MUSUBI (MegaCam Ultra-deep Survey: -Band Imaging)-Data for the COSMOS and SXDS Fields
Wei-Hao Wang, Sebastien Foucaud, Bau-Ching Hsieh +11
The Subaru Hyper Suprime-Cam (HSC) Strategic Survey is the latest-generation multi-band optical imaging survey for galaxy evolution and structure formation. The "Ultra-Deep" compon…
Star Formation at From the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH)
Charles L. Steinhardt, Josh S. Speagle, Peter Capak +21
Using the first 50% of data collected for the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) observations on the 1.8 deg Cosmological Evolution Survey (COSMOS) we es…
The Taiwan Extragalactic Astronomical Data Center
Sébastien Foucaud, Yasuhiro Hashimoto, Meng-Feng Tsai +2
Founded in 2010, the Taiwan Extragalactic Astronomical Data Center (TWEA-DC) has for goal to propose access to large amount of data for the Taiwanese and International community, f…
The Concentration-Density Relation of Galaxies in Las Campanas Redshift Survey
Yasuhiro Hashimoto, Augustus Oemler
We report the results of the evaluation of the ``concentration-density'' relation of galaxies in the local universe, taking advantage of the very large and homogeneous data set ava…