562 citations · 2.8k across the 51 of their papers we have counts for
27 papers · 1 filter
Formation of Heavy Seed Black Holes and Little Red Dots-like Compact Clusters in Metal-enriched Star-forming Regions
Sunmyon Chon, Shingo Hirano, Ke-Jung Chen +1
The origin of supermassive black holes (SMBHs) in the early Universe remains uncertain. While the classical direct-collapse scenario requires pristine gas exposed to intense Lyman-…
Pebbles to Gems: Intermediate-mass black holes in the first star clusters
Benedetta Mestichelli, Manuel Arca Sedda, Marta Volonteri +9
The rapid assembly of supermassive black holes (SMBHs) observed at requires efficient seeding mechanisms in the early Universe. Population III (Pop. III) star clusters…
Towards A Universal Analytical Model of Population III Star Formation: A Bridge Between Cosmological Scales and Protostars
James Gurian, Boyuan Liu, Donghui Jeong +4
We construct an analytical model of Population III star formation that connects the cosmological radiation background to sub-AU protostellar disk fragmentation, a dynamic range ina…
Formation of first star clusters under the supersonic gas flow -- III. Environmental trends and halo-to-halo scatter in the Pop III IMF
Shingo Hirano, Yusuke Sakai, Hideyuki Umeda
The first generations of stars ionised and enriched their host galaxies and seeded the growth of massive black holes. Models often assume that Pop III stellar masses in different m…
Dark Matter Density Profile Around a Newborn First Star
Shingo Hirano, Naoki Yoshida
Ambient dark matter (DM) around binary black holes can imprint characteristic signatures on gravitational waves emitted from their merger. The exact signature depends sensitively o…
An Analytic Model of Gravitational Collapse Induced by Radiative Cooling: Instability Scale, Infall Velocity, and Accretion Rate
James Gurian, Boyuan Liu, Donghui Jeong +3
We present an analytic description of the spherically symmetric gravitational collapse of radiatively cooling gas clouds, which illustrates the mechanism by which radiative cooling…
Towards a universal analytical model for Population III star formation: interplay between feedback and fragmentation
Boyuan Liu, James Gurian, Kohei Inayoshi +4
JWST has brought us new insights into Cosmic Dawn with tentative detection of the unique signatures of metal-free Population III (Pop III) stars, such as strong HeII emission, extr…
Low-mass Pop III star formation due to the HD-cooling induced by weak Lyman-Werner radiation
Sho Nishijima, Shingo Hirano, Hideyuki Umeda
Lyman-Werner (LW) radiation photodissociating molecular hydrogen (H) influences the thermal and dynamical evolution of the Population III (Pop III) star-forming gas cloud. The…
Secondary outflow driven by the protostar Ser-emb 15 in Serpens
Asako Sato, Kazuki Tokuda, Masahiro N. Machida +6
We present the detection of a secondary outflow associated with a Class I source, Ser-emb 15, in the Serpens Molecular Cloud. We reveal two pairs of molecular outflows consisting o…
Early Structure Formation from Primordial Density Fluctuations with a Blue, Tilted Power Spectrum: High-Redshift Galaxies
Shingo Hirano, Naoki Yoshida
Recent observations by the James Webb Space Telescope (JWST) discovered unexpectedly abundant luminous galaxies at high redshift, posing possibly a severe challenge to popular gala…
Formation of first star clusters under the supersonic gas flow -- I. Morphology of the massive metal-free gas cloud
Shingo Hirano, Youcheng Shen, Sho Nishijima +2
We performed simulations of the first star formation with initial supersonic gas flows relative to the dark matter at the cosmic recombination era. Increasing the initial stre…
Crescent-Shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA
Naoto Harada, Kazuki Tokuda, Hayao Yamasaki +6
We report on an Atacama Large Millimeter/submillimeter Array (ALMA) study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12CO (J=2-1) imag…
Exponentially amplified magnetic field eliminates disk fragmentation around the Population III protostar
Shingo Hirano, Masahiro N. Machida
One critical remaining issue to unclear the initial mass function of the first (Population III) stars is the final fate of secondary protostars formed in the accretion disk, specif…
FAUST III. Misaligned rotations of the envelope, outflow, and disks in the multiple protostellar system of VLA 16232417
Satoshi Ohashi, Claudio Codella, Nami Sakai +69
We report a study of the low-mass Class-0 multiple system VLA 1623AB in the Ophiuchus star-forming region, using HCO (), CS (), and CCH () lines as…
Supermassive Star Formation in Magnetized Atomic-Cooling Gas Clouds: Enhanced Accretion, Intermittent Fragmentation, and Continuous Mergers
Shingo Hirano, Masahiro N. Machida, Shantanu Basu
The origin of supermassive black holes (with ) in the early universe (redshift ) remains poorly understood. Gravitational collapse of a massive…
The Birth of a Massive First-Star Binary
Kazuyuki Sugimura, Tomoaki Matsumoto, Takashi Hosokawa +2
We study the formation of massive Population III binary stars using a newly developed radiation hydrodynamics code with the adaptive mesh refinement and adaptive ray-tracing method…
Titans of the Early Universe: The Prato Statement on the Origin of the First Supermassive Black Holes
Tyrone E. Woods, Bhaskar Agarwal, Volker Bromm +30
In recent years, the discovery of massive quasars at z~7 has provided a striking challenge to our understanding of the origin and growth of supermassive black holes in the early Un…
Baryon-dark matter scattering and first star formation
Shingo Hirano, Volker Bromm
The recent detection of the sky-averaged 21-cm cosmological signal indicates a stronger absorption than the maximum allowed value based on the standard model. One explanation for t…
Angular momentum transfer in primordial discs and the rotation of the first stars
Shingo Hirano, Volker Bromm
We investigate the rotation velocity of the first stars by modelling the angular momentum transfer in the primordial accretion disc.Assessing the impact of magnetic braking, we con…
Metal-poor star formation triggered by the feedback effects from Pop III stars
Gen Chiaki, Hajime Susa, Shingo Hirano
Metal enrichment by the first-generation (Pop III) stars is the very first step of the matter cycle in the structure formation and it is followed by the formation of extremely meta…
Formation of the first star clusters and massive star binaries by fragmentation of filamentary primordial gas clouds
Shingo Hirano, Naoki Yoshida, Yuya Sakurai +1
We perform a set of cosmological simulations of early structure formation with incorporating baryonic streaming motions. We present a case where a significantly elongated gas cloud…
Formation of Intermediate-Mass Black Holes through Runaway Collisions in the First Star Clusters
Yuya Sakurai, Naoki Yoshida, Michiko S. Fujii +1
We study the formation of massive black holes in the first star clusters. We first locate star-forming gas clouds in proto-galactic haloes of in c…
Formation and survival of Population III stellar systems
Shingo Hirano, Volker Bromm
The initial mass function of the first, Population III (Pop III), stars plays a vital role in shaping galaxy formation and evolution in the early Universe. One key remaining issue…
Cosmological Simulations of Early Blackhole Formation: Halo Mergers, Tidal Disruption, and the Conditions for Direct Collapse
Sunmyon Chon, Shingo Hirano, Takashi Hosokawa +1
Gravitational collapse of a massive primordial gas cloud is thought to be a promising path for the formation of supermassive blackholes in the early universe. We study conditions f…