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Gamma rays from a reverse shock with turbulent magnetic fields in GRB 180720B
Makoto Arimoto, Katsuaki Asano, Koji S. Kawabata +14
Gamma-ray bursts (GRBs) are the most electromagnetically luminous cosmic explosions. They are powered by collimated streams of plasma (jets) ejected by a newborn stellar-mass black…
Bridging between type IIb and Ib supernovae: SN IIb 2022crv with a very thin Hydrogen envelope
Anjasha Gangopadhyay, Keiichi Maeda, Avinash Singh +26
We present optical, near-infrared, and radio observations of supernova (SN) SN~IIb 2022crv. We show that it retained a very thin H envelope and transitioned from a SN~IIb to a SN~I…
Systematic Investigation of Very Early-Phase Spectra of Type Ia Supernovae
Mao Ogawa, Keiichi Maeda, Miho Kawabata
It has been widely accepted that Type Ia supernovae (SNe Ia) are thermonuclear explosions of a CO white dwarf. However, the natures of the progenitor system(s) and explosion mechan…
SN 2018gj: A Short-plateau Type II Supernova with Persistent Blue-shifted H-alpha Emission
Rishabh Singh Teja, Avinash Singh, D. K. Sahu +7
We present an extensive, panchromatic photometric (UV, Optical, and NIR) and low-resolution optical spectroscopic coverage of a Type IIP supernova SN 2018gj that occurred on the ou…
The broad-lined Type-Ic supernova SN 2022xxf with extraordinary two-humped light curves
H. Kuncarayakti, J. Sollerman, L. Izzo +60
We report on our study of supernova (SN) 2022xxf based on observations obtained during the first four months of its evolution. The light curves (LCs) display two humps of similar m…
Initial Flash and Spectral Formation of Type Ia Supernovae with An Envelope: Applications to Over-luminous SNe Ia
Keiichi Maeda, Ji-an Jiang, Mamoru Doi +2
Over-luminous type Ia supernovae (SNe Ia) show peculiar observational features, for which an explosion of a super-massive white dwarf (WD) beyond the classical Chandrasekhar-limiti…
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…