Article
Astronomy & Astrophysics
Chris Nagele, Hideyuki Umeda, Koh Takahashi
Summary: The assembly of supermassive black holes is challenging due to the presence of quasars at high redshift and the lack of observations of intermediate mass black holes. Direct collapse triggered by the merger of gas-rich galaxies is a plausible scenario for creating supermassive black holes. We investigate the behavior of metal-enriched supermassive stars collapsing due to relativistic radial instability during hydrogen burning. These stars contain both hydrogen and metals and may explode through nuclear reactions, which we simulate through stellar evolution and general relativistic hydrodynamical simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
O. Rodriguez, N. Meza, J. Pineda-Garcia, M. Ramirez
Summary: In this study, the Ni-56 mass estimates for 110 normal Type II supernovae were presented based on their luminosity in the radioactive tail. The Ni-56 mass distribution of the sample ranged from 0.005 to 0.177 solar masses, with an average of 0.037 solar masses. By combining these results with iron isotope ratios, a mean iron yield of 0.040 solar masses for normal Type II supernovae was calculated. The empirical relation between Ni-56 mass and steepness parameter was found to be poorly suited for measuring Ni-56 mass of normal Type II supernovae. Instead, a correlation between Ni-56 mass, steepness parameter, and absolute magnitude at 50 days since explosion was presented to measure Ni-56 masses with a precision around 30 percent.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Thomas Lawson, Marco Pignatari, Richard J. Stancliffe, Jacqueline den Hartogh, Sam Jones, Chris L. Fryer, Brad K. Gibson, Maria Lugaro
Summary: This study examines the impact of core-collapse supernovae on the production of short-lived radioactive isotopes and finds that explosion energy and remnant mass play crucial roles in determining the final yields of these isotopes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Liliya Imasheva, Hans-Thomas Janka, Achim Weiss
Summary: Thermal bombs are widely used to trigger core-collapse supernova explosions. Recent studies have shown that if the explosions are slow, the production of Ni-56, Ni-57, and Ti-44 will be significantly lower than observational estimates. This suggests that rapid explosions are required to match observed abundances. However, our research demonstrates that these conclusions are a result of ignoring the initial collapse of the stellar core in the thermal-bomb modeling. When the initial collapse is included, the anticorrelation between Ni-56 yield and energy-injection time-scale disappears, and even more Ni-56 can be produced by slower explosions. We also propose the most appropriate setup for thermal bombs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Shin-ichiro Fujimoto, Hiroki Nagakura
Summary: The study shows that asymmetric neutrino emissions affect the explosive nucleosynthesis in core-collapse supernovae, leading to significant variations in abundances of elements heavier than nickel in the ejecta. Different degrees of asymmetry in neutrino emissions also impact the average abundances of lighter and heavier elements in the ejecta, with potential evidence of these effects being observable through spectroscopic X-ray observations in the future.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Shin-ichiro Fujimoto, Hiroki Nagakura
Summary: In this study, we investigate the impact of fast neutrino-flavour conversion (FFC) on explosive nucleosynthesis in core-collapse supernovae by including its effects in nucleosynthetic computations. It is found that FFC has little effect on the ejecta compositions for elements lighter than Co, but influences the heavier elements. The role of FFC varies depending on the degree of asymmetric neutrino emission and flavour mixing. Our results suggest that FFC facilitates the production of neutron-rich ejecta in most cases, but may make the ejecta proton-rich if anti-neutrino conversion is more vigorous than neutrino conversion, which can be quantified by simple diagnostics.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Jason L. Sanders, Vasily Belokurov, Kai T. F. Man
Summary: This study confirms the significant contribution of sub-Chandrasekhar mass Type Ia supernovae to the chemical enrichment of the Gaia Sausage galaxy, with yields needing to be metallicity dependent. The research also suggests that in metal-poor systems, sub-Chandrasekhar mass channels may be the dominant contribution to Type Ia supernovae.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Wynn V. Jacobson-Galan, Raffaella Margutti, Charles D. Kilpatrick, John Raymond, Edo Berger, Peter K. Blanchard, Alexey Bobrick, Ryan J. Foley, Sebastian Gomez, Griffin Hosseinzadeh, Danny Milisavljevic, Hagai Perets, Giacomo Terreran, Yossef Zenati
Summary: The late-time bolometric light curve of SN 2019ehk can be predominantly described by the radioactive decay of Co-56, with no statistical evidence for incomplete positron trapping in the supernova ejecta. Although the exact masses of other radioactive isotopes synthesized in SN 2019ehk cannot be constrained by our observations, we estimate a mass ratio limit of M(Co-57)/M(Co-56) <= 0.030. This limit is consistent with the explosive nucleosynthesis produced in the merger of low-mass white dwarfs, a favored progenitor scenario in early-time studies of SN 2019ehk.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
L. Roberti, M. Pignatari, A. Psaltis, A. Sieverding, P. Mohr, Zs. Fulop, M. Lugaro
Summary: The gamma-process nucleosynthesis in core-collapse supernovae is widely accepted, but discrepancies between theory and observations still exist. The average yields of gamma-process nucleosynthesis from massive stars are insufficient and the yields of Mo and Ru isotopes are significantly lower. The study investigates different core-collapse supernova models and finds significant differences in the gamma-process yields and isotopic ratios. The contribution of C-O shell mergers in the supernova progenitors to the gamma-process is also investigated.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
R. Pakmor, Y. Zenati, H. B. Perets, S. Toonen
Summary: Normal type Ia supernovae are believed to originate from the thermonuclear explosion of massive carbon-oxygen white dwarfs, although the exact mechanism is debated. Some theories suggest that helium accretion from a companion could trigger detonations in the accreted shell. However, a study using 3D simulations found that while helium detonation occurred, it did not trigger a carbon detonation in the white dwarf.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
P. Eitner, M. Bergemann, A. J. Ruiter, O. Avril, I. R. Seitenzahl, M. R. Gent, B. Cote
Summary: By studying the abundances of nickel in Galactic stars, we have constrained the role of different Type Ia supernova channels in the chemical enrichment of the Galaxy. We found that non-local thermodynamic equilibrium (NLTE) effects have a negligible impact on the observed nickel abundances in the stars. In LTE, most stars have scaled solar nickel abundances, while in NLTE, we found a mild anti-correlation between nickel and metallicity.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Jordan Schofield, Marco Pignatari, Richard J. Stancliffe, Peter Hoppe
Summary: In this study, isotopic abundances of C, N, Al, Si, and Ti measured in presolar grains were compared with predictions from 21 CCSN models. The research found that high energy models favor the formation of a C/Si zone enriched in C-12, Si-28, and Ti-44.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Brian Nevins, Luke F. Roberts
Summary: The neutrino-driven wind from proto-neutron stars is proposed to be a site for r-process nucleosynthesis. Introducing a secondary heating source, such as gravito-acoustic waves generated by convection inside the proto-neutron star, can change the hydrodynamic conditions in the wind and make them more favorable for r-process nucleosynthesis. The impact of these convection-generated gravito-acoustic waves on nucleosynthesis is investigated, and it is found that they can generate conditions favorable for a strong r-process.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. A. Tucker, B. J. Shappee, C. S. Kochanek, K. Z. Stanek, C. Ashall, G. S. Anand, P. Garnavich
Summary: The study reveals that the late-time luminosity of the Ia supernova 2011fe, up to approximately 2400 days after maximum light, is powered by energy input from both Co-57 and Fe-55. This marks the first detection of Fe-55 in an Ia supernova. Isotopic abundance provides direct constraints on the burning conditions experienced by the white dwarf, leading to limitations on two classes of explosion models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. Reichert, M. Obergaulinger, M. A. Aloy, M. Gabler, A. Arcones, F. K. Thielemann
Summary: Magnetorotational supernovae are a rare type of core-collapse supernovae that involve magnetic fields and rotation in the explosion dynamics. Post-processed nucleosynthesis of neutrino-MHD supernova models reveals three mechanisms for heavy r-process element production. The study highlights the role of magnetorotational supernovae in hypernovae, superluminous supernovae, and heavy element synthesis.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Takashi J. Moriya, Ji-an Jiang, Naoki Yasuda, Mitsuru Kokubo, Kojiro Kawana, Keiichi Maeda, Yen-Chen Pan, Robert M. Quimby, Nao Suzuki, Ichiro Takahashi, Masaomi Tanaka, Nozomu Tominaga, Ken'ichi Nomoto, Jeff Cooke, Lluis Galbany, Santiago Gonzalez-Gaitan, Chien-Hsiu Lee, Giuliano Pignata
Summary: A long-term deep transient survey was conducted using the Hyper Suprime-Cam (HSC) on the Subaru telescope from late 2016 to early 2020. The survey discovered some supernovae lasting for more than a year, with about 40% of Type IIn supernovae having long-lasting light curves, but no plausible pair-instability supernova candidates lasting for more than a year were found. The survey also helped constrain the luminous pair-instability supernova rate up to z similar or equal to 3.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Takashi J. Moriya, Ke-Jung Chen, Kimihiko Nakajima, Nozomu Tominaga, Sergei Blinnikov
Summary: The study presents the expected observational properties of a general relativistic instability supernova originating from supermassive primordial stars. It suggests that these events could be observed at high redshifts and potentially even higher with deep near-infrared imaging, providing a way to identify them based on their extremely red color compared to other sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Takayuki Ohgami, Nozomu Tominaga, Yousuke Utsumi, Yuu Niino, Masaomi Tanaka, Smaranika Banerjee, Ryo Hamasaki, Michitoshi Yoshida, Tsuyoshi Terai, Yuhei Takagi, Tomoki Morokuma, Mahito Sasada, Hiroshi Akitaya, Naoki Yasuda, Kenshi Yanagisawa, Ryou Ohsawa
Summary: After the detection of the gravitational wave event S190510g, scientists conducted target-of-opportunity imaging observations using the Hyper Suprime-Cam on the Subaru Telescope, and utilized various methods to identify potential optical counterparts of S190510g. By comparing observational depth with a kilonova light-curve model, they were able to draw important conclusions.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2021)
Article
Astronomy & Astrophysics
Tatsuya Nakaoka, Keiichi Maeda, Masayuki Yamanaka, Masaomi Tanaka, Miho Kawabata, Takashi J. Moriya, Koji S. Kawabata, Nozomu Tominaga, Kengo Takagi, Fumiya Imazato, Tomoki Morokuma, Shigeyuki Sako, Ryou Ohsawa, Takashi Nagao, Ji-an Jiang, Umut Burgaz, Kenta Taguchi, Makoto Uemura, Hiroshi Akitaya, Mahito Sasada, Keisuke Isogai, Masaaki Otsuka, Hiroyuki Maehara
Summary: The study presents optical and near-infrared observations of SN 2019ehk, initially classified as a Type Ib supernova but later identified as a Ca-rich transient with some unique properties. Analysis suggests that it may be a candidate for a low-mass He star explosion, potentially forming a double neutron star binary system. Candidates for low-mass stripped envelope SNe, including ultra-stripped envelope SN candidates, seem to form a subpopulation among Ca-rich transients, associated with young population.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Bunyo Hatsukade, Nozomu Tominaga, Tomoki Morokuma, Kana Morokuma-Matsui, Yoichi Tamura, Kotaro Niinuma, Masao Hayashi, Yuichi Matsuda, Kazuhiro Motogi
Summary: The time variability of late-time radio emission in a Type I superluminous supernova, PTF10hgi, at z = 0.0987 was reported. Significant variability of the late-time radio light curve in an SLSN was detected for the first time, with possible origins being discussed. Combination with previous measurements allowed for the constraint of rise and decay phases of the radio light curve, indicating possible scenarios such as a magnetar wind nebula or an active galactic nucleus.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
Egor Urvachev, Dmitry Shidlovski, Nozomu Tominaga, Semyon Glazyrin, Sergei Blinnikov
Summary: This study presents the implementation of the M1 approximation of radiation transfer for simulating superluminous supernovae, demonstrating its accuracy in one-dimensional and spherically symmetric simulations, as well as its limitations in multidimensional simulations.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2021)
Article
Astronomy & Astrophysics
Miho N. Ishigaki, Tilman Hartwig, Yuta Tarumi, Shing-Chi Leung, Nozomu Tominaga, Chiaki Kobayashi, Mattis Magg, Aurora Simionescu, Ken'ichi Nomoto
Summary: Stellar and supernova nucleosynthesis in the early universe have set the stage for structure formation, but their nature remains unclear. By comparing elemental abundances and supernova models, we identified the contributions of different types of supernovae to the metal enrichment of the oldest stars in the Galactic halo.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Bunyo Hatsukade, Nozomu Tominaga, Tomoki Morokuma, Kana Morokuma-Matsui, Yuichi Matsuda, Yoichi Tamura, Kotaro Niinuma, Kazuhiro Motogi
Summary: This study presents the results of 3 GHz radio continuum observations of 23 superluminous supernovae and their host galaxies, revealing obscured star formation in some host galaxies. The research also constrains the parameters of afterglows and pulsar wind nebulae models.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Ji-an Jiang, Keiichi Maeda, Miho Kawabata, Mamoru Doi, Toshikazu Shigeyama, Masaomi Tanaka, Nozomu Tominaga, Ken'ichi Nomoto, Yuu Niino, Shigeyuki Sako, Ryou Ohsawa, Malte Schramm, Masayuki Yamanaka, Naoto Kobayashi, Hidenori Takahashi, Tatsuya Nakaoka, Koji S. Kawabata, Keisuke Isogai, Tsutomu Aoki, Sohei Kondo, Yuki Mori, Ko Arimatsu, Toshihiro Kasuga, Shin-ichiro Okumura, Seitaro Urakawa, Daniel E. Reichart, Kenta Taguchi, Noriaki Arima, Jin Beniyama, Kohki Uno, Taisei Hamada
Summary: This Letter reports the discovery of a peculiar overluminous Type Ia supernova, SN 2020hvf, with a prominent flash observed in the early stages after the supernova explosion. Numerical simulations suggest that the early flash is likely generated from the interaction between circumstellar material and supernova ejecta, indicating a confined dense environmental formation around the progenitor of SN 2020hvf. The findings imply that SN 2020hvf may originate from a super-Chandrasekhar-mass white dwarf, and further investigations are needed to understand the explosion mechanisms and progenitor of this peculiar supernova.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
Yuu Niino, Mamoru Doi, Shigeyuki Sako, Ryou Ohsawa, Noriaki Arima, Ji-an Jiang, Nozomu Tominaga, Masaomi Tanaka, Di Li, Chen-Hui Niu, Chao-Wei Tsai, Naoto Kobayashi, Hidenori Takahashi, Sohei Kondo, Yuki Mori, Tsutomu Aoki, Ko Arimatsu, Toshihiro Kasuga, Shin-ichiro Okumura
Summary: This study conducted optical and radio observations of repeating fast radio burst (FRB) 20190520B, and found no corresponding optical emission. The research suggests that current radio-optical spectral energy distributions (SEDs) and certain theoretical models can be ruled out for bright FRBs with a radio fluence of 5 Jy ms or greater.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Ataru Tanikawa, Gen Chiaki, Tomoya Kinugawa, Yudai Suwa, Nozomu Tominaga
Summary: The study examines whether metal-free stars, or Population III stars, can be the dominant origin of merging binary black holes and extremely metal-poor stars. It finds that the abundance pattern of extremely metal-poor stars imposes constraints on the mass range of Population III stars, while the observed black hole merger rate requires a Pop III star formation efficiency 10 times higher than predicted.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2022)
Article
Astronomy & Astrophysics
Haining Li, Wako Aoki, Tadafumi Matsuno, Qianfan Xing, Takuma Suda, Nozomu Tominaga, Yuqin Chen, Satoshi Honda, Miho N. Ishigaki, Jianrong Shi, Jingkun Zhao, Gang Zhao
Summary: We conducted a study analyzing the abundances of over 20 elements in 385 very metal-poor stars using data from the LAMOST survey and Subaru Telescope. This study provides important insights into the evolutionary stages and abundance trends of these stars and also reported new outliers and updates to previous findings.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Ji-an Jiang, Naoki Yasuda, Keiichi Maeda, Nozomu Tominaga, Mamoru Doi, Zeljko Ivezic, Peter Yoachim, Kohki Uno, Takashi J. Moriya, Brajesh Kumar, Yen-Chen Pan, Masayuki Tanaka, Masaomi Tanaka, Kenichi Nomoto, Saurabh W. Jha, Pilar Ruiz-Lapuente, David Jones, Toshikazu Shigeyama, Nao Suzuki, Mitsuru Kokubo, Hisanori Furusawa, Satoshi Miyazaki, Andrew J. Connolly, D. K. Sahu, G. C. Anupama
Summary: In this Letter, the discovery of an ultraluminous fast-evolving transient in rest-frame UV wavelengths, MUSSES2020J, is reported and the possible physical mechanisms powering this extreme transient are discussed.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
M. G. Dainotti, B. De Simone, K. M. Islam, K. Kawaguchi, T. J. Moriya, T. Takiwaki, N. Tominaga, A. Gangopadhyay
Summary: This study investigates the relationships among gamma-ray bursts, afterglows, and associated supernova properties. A new correlation is found, suggesting that brighter optical plateaus are accompanied by larger peak times of supernovae.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Tilman Hartwig, Miho N. Ishigaki, Chiaki Kobayashi, Nozomu Tominaga, Ken'ichi Nomoto
Summary: By analyzing extremely metal-poor stars in the Milky Way, scientists have revealed the nature of the first stars. They classify these stars into mono- or multi-enriched using data-driven methods and find that the majority of extremely metal-poor stars are likely multi-enriched, suggesting that the first stars were born in small clusters.
ASTROPHYSICAL JOURNAL
(2023)
