144 citations · 1.1k across the 67 of their papers we have counts for
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Spectral and photometric variability of SS 433 observed with XRISM and simultaneous optical and near-infrared telescopes
Yusuke Sakai, Shinya Yamada, Yuta Okada +36
We present results from coordinated multiwavelength observations of the SS 433, obtained with XRISM, optical telescopes, and near-infrared camera during 2024 April and 2025 March.…
Multiband Optical Photometric and Spectroscopic Monitoring of the 2024 Flare Event in Transition Blazar OP313
TianFang Zhang, Mitsuru Kokubo, Mamoru Doi +19
Blazars are active galactic nuclei known for their extreme variability, offering unique opportunities to study jet physics and high-energy emission mechanisms. In 2024, the Flat Sp…
XRISM reveals a variable, multi-phase outflow-inflow structure during the X-ray obscured 2024 outburst of the black hole transient V4641 Sgr
Maxime Parra, Megumi Shidatsu, Ryota Tomaru +23
We report the results of a simultaneous X-ray and optical spectroscopy campaign on the Galactic black hole X-ray binary V4641 Sgr, carried out with XRISM and the Seimei telescope d…
Evolution of Accretion Disk Structure of the Black Hole X-ray Binary MAXI J1820070 during the Rebrightening Phase
Tomohiro Yoshitake, Megumi Shidatsu, Yoshihiro Ueda +18
To understand the evolution of global accretion disk structure in the ``rebrightening'' phase of MAXI J1820070, we perform a comprehensive analysis of its near infrared/optical/…
SN 2021foa: the bridge between SN IIn and Ibn
Anjasha Gangopadhyay, Naveen Dukiya, Takashi J Moriya +26
We present the long-term photometric and spectroscopic analysis of a transitioning SN~IIn/Ibn from 10.8 d to 150.7 d post -band maximum. SN~2021foa shows prominent He {\sc i}…
Intermediate-luminosity Type IIP SN 2021gmj: a low-energy explosion with signatures of circumstellar material
Yuta Murai, Masaomi Tanaka, Miho Kawabata +28
We present photometric, spectroscopic and polarimetric observations of the intermediate-luminosity Type IIP supernova (SN) 2021gmj from 1 to 386 days after the explosion. The peak…
SN 2020uem: A Possible Thermonuclear Explosion within A Dense Circumstellar Medium (II) The Properties of The CSM from Polarimetry and Light Curve Modeling
Kohki Uno, Takashi Nagao, Keiichi Maeda +11
Type IIn/Ia-CSM supernovae (SNe IIn/Ia-CSM) are classified by their characteristic spectra, which exhibit narrow hydrogen emission lines originating from a strong interaction with…
SN 2020uem: A Possible Thermonuclear Explosion within A Dense Circumstellar Medium (I) The Nature of Type IIn/Ia-CSM SNe from Photometry and Spectroscopy
Kohki Uno, Keiichi Maeda, Takashi Nagao +18
We have performed intensive follow-up observations of a Type IIn/Ia-CSM SN (SN IIn/Ia-CSM), 2020uem, with photometry, spectroscopy, and polarimetry. In this paper, we report on the…
Comprehensive coverage of particle acceleration and kinetic feedback from the stellar mass black hole V404 Cygni
R. P. Fender, K. P. Mooley, S. E. Motta +8
We present analysis of comprehensive radio observations of the black hole V404 Cyg during its 2015 outburst. These data represent the best ever coverage of jet production and parti…
Discovery of the Fastest Early Optical Emission from Overluminous SN Ia 2020hvf: A Thermonuclear Explosion within a Dense Circumstellar Environment
Ji-an Jiang, Keiichi Maeda, Miho Kawabata +28
In this Letter we report a discovery of a prominent flash of a peculiar overluminous Type Ia supernova, SN 2020hvf, in about 5 hours of the supernova explosion by the first wide-fi…
Optical Variability Correlated with X-ray Spectral Transition in the Black-Hole Transient ASASSN-18ey = MAXI J1820+070
Keito Niijima, Mariko Kimura, Yasuyuki Wakamatsu +49
How a black hole accretes matter and how this process is regulated are fundamental but unsolved questions in astrophysics. In transient black-hole binaries, a lot of mass stored in…
Intermediate Luminosity Type Iax SN 2019muj With Narrow Absorption Lines: Long-Lasting Radiation Associated With a Possible Bound Remnant Predicted by the Weak Deflagration Model
Miho Kawabata, Keiichi Maeda, Masayuki Yamanaka +23
We present comprehensive spectroscopic and photometric analyses of the intermediate luminosity Type Iax supernova (SN Iax) 2019muj based on multi-band datasets observed through the…
Follow-up Observations for IceCube-170922A: Detection of Rapid Near-Infrared Variability and Intensive Monitoring of TXS 0506+056
Tomoki Morokuma, Yousuke Utsumi, Kouji Ohta +35
We present our follow-up observations to search for an electromagnetic counterpart of the IceCube high-energy neutrino, IceCube-170922A. Monitoring observations of a likely counter…
Calcium-rich Transient SN 2019ehk in A Star-Forming Environment: Yet Another Candidate for An Ultra-Stripped Envelope Supernova
Tatsuya Nakaoka, Keiichi Maeda, Masayuki Yamanaka +20
We present optical and near-infrared observations of SN~Ib~2019ehk. We show that it evolved to a Ca-rich transient according to its spectral properties and evolution in late phases…
SN 2018hna: 1987A-like supernova with a signature of shock breakout
Avinash Singh, D. K. Sahu, G. C. Anupama +22
High cadence ultraviolet, optical and near-infrared photometric and low-resolution spectroscopic observations of the peculiar Type II supernova (SN) 2018hna are presented. The earl…
Type Ia SN 2019ein: New Insights into the Similarities and diversities among High-Velocity SNe Ia
Miho Kawabata, Keiichi Maeda, Masayuki Yamanaka +38
We present optical observations of type Ia supernova (SN) 2019ein, starting at 2 days after the estimated explosion date. The spectra and the light curves show that SN 2019ein belo…
Rapid Optical Variations Correlated with X-rays in the 2015 Second Outburst of V404 Cygni (GS 2023338)
Mariko Kimura, Taichi Kato, Keisuke Isogai +24
We present optical multi-colour photometry of V404 Cyg during the outburst from December, 2015 to January, 2016 together with the simultaneous X-ray data. This outburst occurred le…
Repetitive Patterns in Rapid Optical Variations in the Nearby Black-hole Binary V404 Cygni
Mariko Kimura, Keisuke Isogai, Taichi Kato +65
How black holes accrete surrounding matter is a fundamental, yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion…
No Evidence of Intrinsic Optical/Near-Infrared Linear Polarization for V404 Cygni During its Bright Outburst in 2015: Broadband Modeling and Constraint on Jet Parameters
Y. T. Tanaka, R. Itoh, M. Uemura +39
We present simultaneous optical and near-infrared (NIR) polarimetric results for the black hole binary V404 Cygni spanning the duration of its 7-day long optically-brightest phase…