Article
Astronomy & Astrophysics
Takashi J. Moriya, Yuichi Harikane, Akio K. Inoue
Summary: The rate of general relativistic instability supernovae (GRSNe) at 10≤z≤15 is constrained to be less than about 8 x 10(-7) Mpc(-3) yr(-1) for the first time using early JWST deep field data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
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
B. Novosyadlyj, Yu. Kulinich, B. Melekh, V. Shulga
Summary: This study examines the formation and destruction of the first molecules during the Dark Ages and Cosmic Dawn, evaluating the luminosity of protogalaxy clumps (halos) in molecular lines. The impact of photodissociation processes on molecules like H-2 and HD is significant before full reionization, while the number density of helium hydride ions HeH+ shows complicated dependences on halo kinetic temperature and models of the first light. The brightness temperature evolution of individual halos in rotational lines of certain molecules does not exceed microkelvin, but detection could provide important insights into physical processes during the formation of the first stars and galaxies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Philippa S. Cole, Joseph Silk
Summary: The production and existence of primordial black holes can impact the primordial power spectrum and matter power spectrum, potentially leading to observable effects on the 21 cm power spectrum. It is crucial to include the contribution from primordial fluctuations in predicting the 21 cm signal in order to avoid underestimation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Multidisciplinary Sciences
Guido Roberts-Borsani, Tommaso Treu, Wenlei Chen, Takahiro Morishita, Eros Vanzella, Adi Zitrin, Pietro Bergamini, Marco Castellano, Adriano Fontana, Karl Glazebrook, Claudio Grillo, Patrick L. Kelly, Emiliano Merlin, Themiya Nanayakkara, Diego Paris, Piero Rosati, Lilan Yang, Ana Acebron, Andrea Bonchi, Kit Boyett, Marusa Bradac, Gabriel Brammer, Tom Broadhurst, Antonello Calabro, Jose M. Diego, Alan Dressler, Lukas J. Furtak, Alexei V. Filippenko, Alaina Henry, Anton M. Koekemoer, Nicha Leethochawalit, Matthew A. Malkan, Charlotte Mason, Amata Mercurio, Benjamin Metha, Laura Pentericci, Justin Pierel, Steven Rieck, Namrata Roy, Paola Santini, Victoria Strait, Robert Strausbaugh, Michele Trenti, Benedetta Vulcani, Lifan Wang, Xin Wang, Rogier A. Windhorst
Summary: In the early universe, sources of ultraviolet photons played a crucial role in ionizing intergalactic hydrogen, making the universe transparent to UV radiation. Fainter galaxies that are surrounded by neutral gas were believed to dominate the photon budget. By using the James Webb Space Telescope and gravitational lensing, the ultra-faint galaxy JD1 was spectroscopically confirmed at a redshift of z = 9.79, showing a compact and complex morphology with low stellar mass and subsolar metallicity.
Article
Astronomy & Astrophysics
Mihir Kulkarni, Eli Visbal, Greg L. Bryan
Summary: This study constrains the critical dark matter halo mass (M (crit)) for Population III stars as a function of various factors using cosmological simulations, providing a useful fit for semi-analytical models of early galaxy formation. The results show that the Lyman-Werner flux, baryon-dark matter streaming, redshift, and their combined effects have different impacts on M (crit).
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Hyunbae Park, Paul R. Shapiro, Kyungjin Ahn, Naoki Yoshida, Shingo Hirano
Summary: Recent studies have shown that recombination in small-scale gas clouds can affect the history of cosmic reionization, and the streaming velocity has a significant impact on local reionization history, especially as the ionizing efficiency of galaxies decreases.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Tanja Rindler-Daller, Katherine Freese, Richard H. D. Townsend, Luca Visinelli
Summary: This study investigates the properties and pulsation modes of dark stars, showing that acoustic modes in smaller dark stars are excited by mechanisms in layers with partially ionized hydrogen or helium. It also reveals that mass-loss rates potentially induced by pulsations are negligible compared to accretion rates.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Anna T. P. Schauer, Simon C. O. Glover, Ralf S. Klessen, Paul Clark
Summary: Population III star formation occurs in small dark matter minihaloes with specific conditions for H-2 cooling. The minimum mass scale for this formation is influenced by baryon streaming relative to dark matter and photodissociation of H-2 by a high redshift LW background. Results from high resolution cosmological simulations show that these effects are additive and impact M-min and M-ave.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Yuxiang Qin, J. Stuart B. Wyithe, Pascal A. Oesch, Garth D. Illingworth, Ecaterina Leonova, Simon J. Mutch, Rohan P. Naidu
Summary: This study investigates the Ly alpha IGM transmission and environment of bright galaxies during the epoch of reionization. It reveals that brighter galaxies are less affected by damping-wing absorption, while the transmission of fainter galaxies depends on UV luminosity. The brightest sources are located in the largest ionized regions, leading to a lower incidence of Ly alpha detection in fainter galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Dominic Anstey, Eloy de Lera Acedo, Will Handley
Summary: The study found that the 21 cm high-order waterline absorption line signal is susceptible to distortions from foregrounds, proposing a new method to model the foregrounds to adapt to chromatic distortions. Using Bayesian algorithm and evidence comparison allows reliable detection of the 21 cm signal.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
James E. Davies, Rupert A. C. Croft, Tiziana Di-Matteo, Bradley Greig, Yu Feng, J. Stuart B. Wyithe
Summary: The study uses BLUETIDES simulation to investigate the measurement of ionized regions around bright galaxies at the beginning of reionization. They find that with proper foreground subtraction, a 5 sigma detection of these regions can be made with 30 images around some of the brightest galaxies in the simulation. Additionally, the study shows that reducing foreground contamination in Fourier space can significantly improve the detection of ionized regions at redshift z=9.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Boyuan Liu, Volker Bromm
Summary: The study reveals that a portion of Pop III binary remnants from early galaxy formation will be gravitationally pulled into nuclear star clusters for mergers, creating massive black holes, with a peak merger rate density observed at higher redshifts. These merger events are mainly hosted by low-mass nuclear star clusters, leading to a high detection rate in third-generation gravitational wave detectors.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Boyuan Liu, Saiyang Zhang, Volker Bromm
Summary: In this study, we use cosmological hydrodynamic zoom-in simulations and semi-analytical models to investigate the effects of primordial black holes (PBHs) on the formation of the first stars. We find that the presence of PBHs does not significantly alter the standard model of star formation in molecular-cooling minihaloes, but it does shift star formation to larger haloes and accelerates structure formation at larger scales. Additionally, the accretion of Lyman-Werner photons from PBHs in atomic-cooling haloes may facilitate the formation of direct-collapse black holes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Keir K. Rogers, Hiranya Peiris
Summary: The study presents a general framework for obtaining robust bounds on the nature of dark matter using cosmological N-body simulations and Lyman-alpha forest data. They construct an emulator of hydrodynamical simulations, which is a flexible and accurate model for predicting the response of the Lyman-alpha forest flux power spectrum to different dark matter models, the state of the intergalactic medium, and the primordial power spectrum. The framework can be optimized for the analysis of many other dark matter candidates and demonstrates a powerful approach for robust and computationally efficient inference from the cosmic large-scale structure.
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
Computer Science, Cybernetics
Yuko Ikkatai, Tilman Hartwig, Naohiro Takanashi, Hiromi M. Yokoyama
Summary: This study investigates public attitudes toward AI ethics using four scenarios and identifies variations in opinions depending on the scenario. Age is significantly related to the themes across the scenarios, while gender and understanding of AI are differently related depending on the themes and scenarios. Thorough explanation of the eight themes is necessary, and the Octagon measurement may aid in understanding societal perception and potential issues surrounding rapidly permeating AI technologies.
INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION
(2022)
Article
Computer Science, Artificial Intelligence
Tilman Hartwig, Yuko Ikkatai, Naohiro Takanashi, Hiromi M. Yokoyama
Summary: The development of an AI ethics scale is important for understanding public attitudes towards AI research ethics and promoting its application in society. This study investigated public attitudes towards AI ethics in Japan and the US, finding that country and age are informative factors. The proposed scale, consisting of 13 questions, can be simplified to three, covering ethics, tradition, and policies.
Article
Astronomy & Astrophysics
Mattis Magg, Itamar Reis, Anastasia Fialkov, Rennan Barkana, Ralf S. Klessen, Simon C. O. Glover, Li-Hsin Chen, Tilman Hartwig, Anna T. P. Schauer
Summary: The study developed a flexible semi-analytical model to track the formation of the first stars and the transition from primordial to metal-enriched star formation. It was found that the recovery time has a strong impact on the redshift at which the transition to metal-enriched star formation occurs, leaving a distinct imprint in the 21-cm signal.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Masataka Aizawa, Kojiro Kawana, Kazumi Kashiyama, Ryou Ohsawa, Hajime Kawahara, Fumihiro Naokawa, Tomoyuki Tajiri, Noriaki Arima, Hanchun Jiang, Tilman Hartwig, Kotaro Fujisawa, Toshikazu Shigeyama, Ko Arimatsu, Mamoru Doi, Toshihiro Kasuga, Naoto Kobayashi, Sohei Kondo, Yuki Mori, Shin-ichiro Okumura, Satoshi Takita, Shigeyuki Sako
Summary: We conducted a wide-field survey for M-dwarf flares using the Tomoe Gozen camera mounted on the Kiso Schmidt telescope with a cadence of one frame per second. We detected 22 flares and found that their light curves differ from those observed in previous studies. These flares represent the bright end of fast optical flares for M dwarfs and are common in magnetically active M dwarfs. Our analysis suggests that the flare light curves can be explained by the chromospheric compression model, and these flares could be a major contamination source for future searches of fast optical transients of unknown types.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2022)
Article
Astronomy & Astrophysics
Tilman Hartwig, Mattis Magg, Li-Hsin Chen, Yuta Tarumi, Volker Bromm, Simon C. O. Glover, Alexander P. Ji, Ralf S. Klessen, Muhammad A. Latif, Marta Volonteri, Naoki Yoshida
Summary: A-SLOTH is the first public code that connects the formation of the first stars and galaxies to observables. It is based on dark matter merger trees and applies analytical methods to simulate the formation of metal-free and metal-poor stars and the transition between them. A-SLOTH is calibrated based on six observables and can be used to constrain the properties of the first stars and high-z galaxies, predict the properties of the oldest and most metal-poor stars in the Milky Way, serve as a subgrid model for larger cosmological simulations, and predict next-generation observables of the early universe.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Shafqat Riaz, Tilman Hartwig, Muhammad A. Latif
Summary: The first stars have not been detected yet, but the upcoming JWST observations may soon reveal their presence. This study uses a semianalytical model to investigate the contribution of Population III stars to high-redshift galaxies, finding that they are most abundant in low-mass halos and less common in high-mass halos. However, Population III-dominated galaxies are too faint to be directly detected with JWST.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
Li-Hsin Chen, Tilman Hartwig, Ralf S. Klessen, Simon C. O. Glover
Summary: This study develops a new analysis method that compares multidimensional observables to a theoretical model using unsupervised clustering algorithms and the Fisher-Freeman-Halton test. Applying the method to observed and simulated satellites, it is found that the fiducial model does not reproduce the mean stellar metallicity well. An improvement to the physical model increases the number of dark matter merger trees with a p-value > 0.01. The method can be easily extended to higher-dimensional data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Betul Uysal, Tilman Hartwig
Summary: Several studies have shown the influence of relative streaming velocity (SV) on structure formation. For the first time, we constrained the local value of SV when the Milky Way formed. Our investigation found that SV delays star formation at high redshift, but has no effect on the total stellar mass or satellites of the Milky Way at redshift z = 0.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Chris Nagele, John D. Silverman, Tilman Hartwig, Junyao Li, Connor Bottrell, Xuheng Ding, Yoshiki Toba
Summary: In this study, optical i-band images of 3096 SDSS quasars and galaxies were analyzed using the Hyper Suprime-Cam Subaru Strategic Program. The presence of nuclear activity was found to be associated with more pronounced components, such as arcs, rings, and bars, suggesting the importance of secular processes and possibly mergers in activating or sustaining black hole growth.
ASTROPHYSICAL JOURNAL
(2023)
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)
Article
Astronomy & Astrophysics
Nina S. Sartorio, A. Fialkov, T. Hartwig, G. M. Mirouh, R. G. Izzard, M. Magg, R. S. Klessen, S. C. O. Glover, L. Chen, Y. Tarumi, D. D. Hendriks
Summary: The properties of X-ray binaries (XRBs) arising from zero metallicity stars and their dependence on the initial mass function (IMF) of primordial stars are explored in this study. The results show that the IMF has a strong effect on the number and X-ray production efficiency of XRBs. Scaling relations between XRBs and their X-ray emission with the local star formation rate are also presented. The findings provide insights for improving X-ray feedback prescriptions in numerical simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Kaitlin C. Rasmussen, Joseph Zepeda, Timothy C. Beers, Vinicius M. Placco, Eric Depagne, Anna Frebel, Sarah Dietz, Tilman Hartwig
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
John D. Silverman, Shenli Tang, Khee-Gan Lee, Tilman Hartwig, Andy Goulding, Michael A. Strauss, Malte Schramm, Xuheng Ding, Rogemar A. Riffel, Seiji Fujimoto, Chiaki Hikage, Masatoshi Imanishi, Kazushi Iwasawa, Knud Jahnke, Issha Kayo, Nobunari Kashikawa, Toshihiro Kawaguchi, Kotaro Kohno, Wentao Luo, Yoshiki Matsuoka, Yuichi Matsuda, Tohru Nagao, Masamune Oguri, Yoshiaki Ono, Masafusa Onoue, Masami Ouchi, Kazuhiro Shimasaku, Hyewon Suh, Nao Suzuki, Yoshiaki Taniguchi, Yoshiki Toba, Yoshihiro Ueda, Naoki Yasuda
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Yuta Tarumi, Tilman Hartwig, Mattis Magg
ASTROPHYSICAL JOURNAL
(2020)