collaborators

6 papers

astro-ph.GA2025

Identification of 40 gravitationally magnified stars in a galaxy at redshift of 0.725

Yoshinobu Fudamoto, Fengwu Sun, Jose M. Diego +44

Strong gravitational magnifications enable to detect faint background sources, resolve their internal structures, and even identify individual stars in distant galaxies. Highly mag…

astro-ph.CO2024

Constraints on primordial black holes from the observed number of Icarus-like ultrahigh magnification events

Hiroki Kawai, Masamune Oguri

Icarus is an individual star observed near the macro-critical curve of the MACS J1149 cluster, with the magnification factor estimated to be an order of thousands. Since microlense…

astro-ph.CO2024

Analytic model for the statistics of ultra-high magnification events

Hiroki Kawai, Masamune Oguri

Highly magnified individual stars such as Icarus and Earendel have recently been observed near critical curves of galaxy clusters with Hubble Space Telescope (HST) observations. Th…

astro-ph.CO2024

Modeling the core-halo mass relation in fuzzy dark matter halos

Hiroki Kawai, Ayuki Kamada, Kohei Kamada +1

Fuzzy dark matter (FDM) is an intriguing candidate alternative to the standard cold dark matter (CDM). The FDM model predicts that dark halos have characteristic core structures ge…

astro-ph.CO2024

Dark Matter distinguished by skewed microlensing in the "Dragon Arc"

Tom Broadhurst, Sung Kei Li, Amruth Alfred +18

Microlensed stars recently discovered by JWST & HST follow closely the winding critical curve of A370 along all sections of the ``Dragon Arc" traversed by the critical curve. These…

astro-ph.CO2024

Analytic approach to astrometric perturbations of critical curves by substructures

Katsuya T. Abe, Hiroki Kawai, Masamune Oguri

Astrometric perturbations of critical curves in strong lens systems are thought to be one of the most promising probes of substructures down to small-mass scales. While a smooth ma…