51 citations · 238 across the 19 of their papers we have counts for
19 papers
A Face-on Accretion Disk Geometry Revealed by Millimeter-wave Periodicity in Sgr A
Kazuki Yanagisawa, Tomoharu Oka, Ryo Ariyama +3
We analyzed 77 epochs of Atacama Large Millimeter/submillimeter Array (ALMA) archival data to investigate flux variability in Sagittarius A (Sgr A), the supermassive black…
Circum-nuclear eccentric gas flow in the Galactic Center revealed by ALMA CMZ Exploration Survey (ACES)
Yoshiaki Sofue, Tomoharu Oka, Steven N. Longmore +41
We analyze the CS (J=2-1) line cube from the internal data release obtained by the large-scale program "ALMA CMZ Exploration Survey (ACES)" to investigate the kinematic structure o…
Parabolic-like Trend in SiO Ratios throughout the Central Molecular Zone: Possible Signature of a Past Nuclear Activity in the Galactic Center
Shunya Takekawa, Tomoharu Oka, Shiho Tsujimoto +5
We report the discovery of a characteristic trend in the intensity ratios of SiO emissions across the Central Molecular Zone (CMZ) of our Galaxy. Using the Nobeyama Radio Observato…
ALMA View of the High-velocity-dispersion Compact Cloud CO 0.02-0.02 at the Galactic Center
Yuhei Iwata, Tomoharu Oka, Shunya Takekawa +2
We report the results of observations toward the center of the molecular cloud CO 0.02-0.02 made using the Atacama Large Millimeter/Submillimeter Array. The successfully obtained 1…
Discovery of the Tadpole Molecular Cloud near the Galactic Nucleus
Miyuki Kaneko, Tomoharu Oka, Hiroki Yokozuka +4
In this paper, we report the discovery of an isolated, peculiar compact cloud with a steep velocity gradient at $2\farcm 6$ northwest of Sgr A*. This ``Tadpole'' molecular cloud is…
Catalog of High Velocity Dispersion Compact Clouds in the Central Molecular Zone of Our Galaxy
Tomoharu Oka, Asaka Uruno, Rei Enokiya +5
This study developed an automated identification procedure for compact clouds with broad velocity widths in the spectral line data cubes of highly crowded regions. The procedure wa…
Broad-velocity-width Molecular Features in the Galactic Plane
Hiroki Yokozuka, Tomoharu Oka, Shunya Takekawa +2
We performed a systematic search for broad-velocity-width molecular features (BVFs) in the disk part of our Galaxy by using the CO J = 1-0 survey data obtained with the Nobeyama Ra…
New Look at the Molecular Superbubble Candidate in the Galactic Center
Shiho Tsujimoto, Tomoharu Oka, Shunya Takekawa +10
The region in the Galactic center is characterized by multiple shell-like structures and their extremely broad velocity widths. We revisit the molecular supe…
Time Variations in the Flux Density of Sgr A* at 230 GHz Detected with ALMA
Yuhei Iwata, Tomoharu Oka, Masato Tsuboi +2
A radio source at the Galactic center Sgr A* is a prime supermassive black hole candidate and therefore key to developing our understanding of them. Time variations in the 230 GHz…
The Fifth Candidate for an Intermediate-mass Black Hole in the Galactic Center
Shunya Takekawa, Tomoharu Oka, Yuhei Iwata +2
We report the results of high-resolution molecular line observations of the high-velocity compact cloud HCN-0.085-0.094 with the Atacama Large Millimeter/submillimeter Array. The H…
An energetic high-velocity compact cloud: CO0.31+0.11
Shunya Takekawa, Tomoharu Oka, Sekito Tokuyama +5
We have discovered an energetic high-velocity compact cloud CO0.31+0.11 in the central molecular zone of our Galaxy. CO0.31+0.11 is located at a projected distance of $\sim 4…
Indication of Another Intermediate-mass Black Hole in the Galactic Center
Shunya Takekawa, Tomoharu Oka, Yuhei Iwata +2
We report the discovery of molecular gas streams orbiting around an invisible massive object in the central region of our Galaxy, based on the high-resolution molecular line observ…
Detection of Another Molecular Bubble in the Galactic Center
Shiho Tsujimoto, Tomoharu Oka, Shunya Takekawa +4
The region in the Galactic center has a high CO =3-2/=1-0 intensity ratio and extremely broad velocity width. This paper reports the detection of five expand…
Millimetre-wave Emission from an Intermediate-Mass Black Hole Candidate in the Milky Way
Tomoharu Oka, Shiho Tsujimoto, Yuhei Iwata +2
It is widely accepted that black holes (BHs) with masses greater than a million solar masses (Msun) lurk at the centres of massive galaxies. The origins of such `supermassive' blac…
Discovery of Two Small High-Velocity Compact Clouds in the Central 10 Parsecs of Our Galaxy
Shunya Takekawa, Tomoharu Oka, Yuhei Iwata +2
We discovered two small high-velocity compact clouds (HVCCs) in HCN and maps of the central 20 pc of our Galaxy. Both HVCCs have broad velocity widths ($ΔV \gtrsim…
Distance to the Low-velocity Cloud in the Direction of the High-velocity Compact Cloud CO--0.40--0.22
Yuhei Iwata, Haruka Kato, Daisuke Sakai +1
CO--0.40--0.22 is a peculiar molecular cloud that is compact and has an extraordinary broad velocity width. It is found in the central molecular zone of our Galaxy. In this directi…
Kinematics of Ultra-High-Velocity Gas in the Expanding Molecular Shell adjacent to the W44 Supernova Remnant
Masaya Yamada, Tomoharu Oka, Shunya Takekawa +6
We mapped the ultra-high-velocity feature (the "Bullet") detected in the expanding molecular shell associated with the W44 supernova remnant using the Nobeyama Radio Observatory 45…
Chiral multicritical points driven by isospin density in the Ginzburg-Landau approach
Yuhei Iwata, Hiroaki Abuki, Katsuhiko Suzuki
We study how a chiral tricritical point (TCP) on QCD phase diagram is affected by the imbalance of up and down quark densities (isospin density), using the generalized Ginzburg-Lan…
Splitting of the chiral critical point and realization of solitonic pion condensate driven by isospin density
Yuhei Iwata, Hiroaki Abuki, Katsuhiko Suzuki
We study the influence of the isospin asymmetry on the phase structure of strongly interacting quark matter near the tricritical point (TCP) using a generalized Ginzburg-Landau app…