arXiv subjects

Taiki Bessho

Publications and source records attributed to Taiki Bessho.

4 recordsLinked to original sources

arXiv2026

Assessing the Impact of Source Confusion for GREX-PLUS based on Deep JWST NIRCam Imaging

We investigate the effects of source confusion expected in observations with GREX-PLUS, a JAXA L-class space infrared telescope mission candidate with a wide-field infrared camera covering 2-8 um with a field of view of 0.50 deg$^2$. For the deep imaging band near 4 um, we calculate the GREX-PLUS PSF and ghost based on the latest optical design, and consider two representative imaging performance cases with PSF FWHM values of 0.9 and 1.2 arcsec. We construct simulated GREX-PLUS images at different depths by convolving JWST NIRCam imaging data from JADES, GLASS, CEERS, and COSMOS-Web with the PSF+ghost kernel. Comparing the limiting magnitudes estimated from random aperture photometry using the same aperture sizes, we find that the simulated GREX-PLUS images are shallower than the original JWST images, with larger deviations for deeper original JWST images. This likely reflects unresolved faint sources and extended PSF+ghost wings from bright sources, which elevate background fluctuations in blank regions. Nevertheless, the limiting magnitudes continue to improve with increasing integration time down to ~27 mag, without a clear plateau at depths comparable to the planned GREX-PLUS deep survey, although the improvement becomes progressively less efficient toward longer integrations. Based on Monte Carlo simulations, we estimate detection completeness and correct the number counts for magnitude bias and incompleteness, finding that confusion-induced blending can reduce the completeness even at magnitudes well above the nominal 5-sigma depth. The completeness-corrected number counts agree well with the JWST-based number counts down to around the detection limit. Overall, our results suggest that statistical studies of faint galaxies remain feasible for GREX-PLUS; however, survey planning should account for less efficient depth improvement toward longer integrations due to source confusion.

astro-ph.GA↗

arXiv2024

First Result for Dark Matter Search by WINERED

The identity of dark matter has been a mystery in astronomy, cosmology, and particle theory for about a century. Bessho, Ikeda, and Yin (2022), three of the current authors, proposed using the state-of-the-art infrared spectrographs, including WINERED at $6.5$m Magellan Clay telescope and NIRSpec at James Webb Space Telescope, as efficient detectors for the indirect detection of dark matter with the mass around eV by measuring the line photons from the dark matter two body decays. Applying this concept, we have performed spectrographic observations of dwarf spheroidal galaxies (dSphs) Leo V and Tucana II using WINERED by utilizing an object-sky-object nodding observation technique for background subtraction. We present the first result from this dark matter search. Employing zero consistent flux data after the sky subtraction, we have established one of the most stringent limits to date on dark matter decaying into line photons in the mass range of $1.8-2.7\,$eV. Our data can also be applied to constrain other spectra of photons from the dSphs.

astro-ph.CO↗

arXiv2022

Indirect Detection of eV Dark Matter via Infrared Spectroscopy

Infrared spectroscopy has been developed significantly. In particular, infrared photons can be measured with high spectral and angular resolution in state-of-art spectrographs. They are sensitive to monochromatic photons due to the decay and annihilation of particles beyond the Standard Model, such as dark matter (DM), while insensitive to background photons that form a continuous spectrum. In this paper, we study the indirect detection of the DM decaying into infrared light using infrared spectrographs. In particular, we show that serious thermal and astrophysical noises can be overcome. As concrete examples, the Warm INfrared Echelle spectrograph to Realize Extreme Dispersion and sensitivity (WINERED) installed at the Magellan Clay 6.5m telescope and Near-Infrared Spectrograph (NIRSpec) at the James Webb Space Telescope (JWST) are discussed. We show that a few hours of measurements of a faint dwarf spheroidal galaxy with WINERED (NIRSpec-like spectrograph) in the Magellan telescope (JWST) can probe an axion-like particle DM in the mass range $m_\phi=1.8 - 2.7\,$eV ($0.5-4\,$eV) with a photon coupling $g_{\phi\gamma\gamma}\gtrsim 10^{-11}{\rm GeV}^{-1}$. Complemental approaches, taking advantage of the high resolutions, such as the measurement of the Doppler shift of the signal photon lines and the possible search of the DM decay around the Milky Way galaxy center with Infrared Camera and Spectrograph (IRCS) at 8.2m Subaru telescope, are also presented.

hep-ph↗

arXiv2016

Topological Membranes, Current Algebras and H-flux - R-flux Duality based on Courant Algebroids

We construct a topological sigma model and a current algebra based on a Courant algebroid structure on a Poisson manifold. In order to construct models, we reformulate the Poisson Courant algebroid by supergeometric construction on a QP-manifold. A new duality of Courant algebroids which transforms H-flux and R-flux is proposed, where the transformation is interpreted as a canonical transformation of a graded symplectic manifold.

hep-th↗