56 citations · 346 across the 22 of their papers we have counts for
24 papers
XMM-Newton Resolves Parsec-scale X-ray Jets in the PeVatron Microquasar V4641 Sgr
Naomi Tsuji, Caterina Tresoldi, Kaya Mori +34
The microquasar V4641 Sagittarii (V4641 Sgr) has recently been established as one of the most powerful Galactic PeV cosmic-ray accelerators (PeVatrons) through the detection of deg…
The Nobeyama 45 m Survey of Shocked Molecular Gas in the Central Molecular Zone. I. Survey Data, Cloud Catalog, and SiO Line-Ratio Trends
Shunya Takekawa, Shiho Tsujimoto, Tomoharu Oka +1
We present large-scale molecular line maps of the Central Molecular Zone (CMZ) in our Galaxy obtained with the Nobeyama Radio Observatory 45 m telescope. The observations cover a 3…
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…
The JWST Galactic Center Survey -- A White Paper
Rainer Schoedel, Steve Longmore, Jonny Henshaw +111
The inner hundred parsecs of the Milky Way hosts the nearest supermassive black hole, largest reservoir of dense gas, greatest stellar density, hundreds of massive main and post ma…
Predicting reliable H column density maps from molecular line data using machine learning
Yoshito Shimajiri, Yasutomo Kawanishi, Shinji Fujita +13
The total mass estimate of molecular clouds suffers from the uncertainty in the H-CO conversion factor, the so-called factor, which is used to convert the C…
Evidence for a gamma-ray molecular target in the enigmatic PeVatron candidate LHAASO J2108+5157
Eduardo de la Fuente, Ivan Toledano-Juárez, Kazumasa Kawata +11
To determine the nature of the PeVatron's emission (hadronic or leptonic), it is essential to characterize the physical parameters of the environment from where it originates. We u…
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…
Distance determination of molecular clouds in the 1st quadrant of the Galactic plane using deep learning : I. Method and Results
Shinji Fujita, A. M. Ito, Yusuke Miyamoto +15
Machine learning has been successfully applied in varied field but whether it is a viable tool for determining the distance to molecular clouds in the Galaxy is an open question. I…
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 $\sim 4…
Indication of Another Intermediate-mass Black Hole in the Galactic Center
Shunya Takekawa, Tomoharu Oka, Yuhei Iwata +2
We report the discovery of molecular gas streams orbiting around an invisible massive object in the central region of our Galaxy, based on the high-resolution molecular line observ…
Magnetohydrodynamic Simulations of a Plunging Black Hole into a Molecular Cloud
Mariko Nomura, Tomoharu Oka, Masaya Yamada +4
Using two-dimensional magnetohydrodynamic simulations, we investigated the gas dynamics around a black hole plunging into a molecular cloud. In these calculations, we assumed a par…
Detection of Another Molecular Bubble in the Galactic Center
Shiho Tsujimoto, Tomoharu Oka, Shunya Takekawa +4
The region in the Galactic center has a high CO =3-2/=1-0 intensity ratio and extremely broad velocity width. This paper reports the detection of five expand…
Millimetre-wave Emission from an Intermediate-Mass Black Hole Candidate in the Milky Way
Tomoharu Oka, Shiho Tsujimoto, Yuhei Iwata +2
It is widely accepted that black holes (BHs) with masses greater than a million solar masses (Msun) lurk at the centres of massive galaxies. The origins of such `supermassive' blac…
Discovery of Two Small High-Velocity Compact Clouds in the Central 10 Parsecs of Our Galaxy
Shunya Takekawa, Tomoharu Oka, Yuhei Iwata +2
We discovered two small high-velocity compact clouds (HVCCs) in HCN and maps of the central 20 pc of our Galaxy. Both HVCCs have broad velocity widths ($ΔV \gtrsim…
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…
Physical Contact between the +20 km/s Cloud and the Galactic Circumnuclear Disk
Shunya Takekawa, Tomoharu Oka, Kunihiko Tanaka
This paper reports the discovery of evidence for physical contact between the Galactic circumnuclear disk (CND) and an exterior giant molecular cloud. The central 10 pc of our Gala…
Signature of an Intermediate-Mass Black Hole in the Central Molecular Zone of Our Galaxy
Tomoharu Oka, Reiko Mizuno, Kodai Miura +1
We mapped the high-velocity compact cloud CO-0.40-0.22 in 21 molecular lines in the 3 mm band using the Nobeyama Radio Observatory 45 m radio telescope. Eighteen lines were detecte…
Millimeter-wave Spectral Line Surveys toward the Galactic Circumnuclear Disk and Sgr A*
Shunya Takekawa, Tomoharu Oka, Kunihiko Tanaka +3
We have performed unbiased spectral line surveys at 3 mm band toward the Galactic circumnuclear disk (CND) and Sgr A* using the Nobeyama Radio Observatory (NRO) 45 m radio telescop…
Millimeter-wave Molecular Line Observations of the Tornado Nebula
Daisuke Sakai, Tomoharu Oka, Kunihiko Tanaka +3
We report the results of millimeter-wave molecular line observations of the Tornado Nebula (G357.7--0.1), which is a bright radio source behind the Galactic Center region. A 15'x15…