8 papers
Production of High Energy Neutrinos in the Coronae of Ultraluminous X-ray Sources
Norita Kawanaka, Shigeo S. Kimura
We investigate the possibility of high-energy neutrino production in coronae associated with ultraluminous X-ray sources (ULXs) as super-Eddington accreting black holes. Adopting t…
Diffusive or Ballistic? Distributions and Spectra of PeV Cosmic Rays around Microquasars
Yutaka Fujita, Rohta Takahashi, Norita Kawanaka
In the standard Galactic cosmic-ray (CR) paradigm, protons are accelerated up to ~1 PeV by Galactic sources. While supernova remnants (SNRs) have been traditionally considered as t…
Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) XXII. Chandra observations of narrow-line quasar candidates at z>6
K. Iwasawa, R. Gilli, F. Vito +13
We report on Chandra X-ray observations of four narrow-line quasar candidates at z~6, selected from the SHELLQs project, based on the Subaru Hyper Suprime-Cam survey. These objects…
Hadronic origin of the very high-energy gamma-ray emission from the low-luminosity AGN in NGC 4278
Asahi Shoji, Yutaka Fujita, Norita Kawanaka +2
The Large High Altitude Air Shower Observatory has detected very high-energy (VHE) gamma rays from NGC 4278, which is known to host a low-luminosity active galactic nucleus (AGN).…
Re-examination of the CO absorption line in the M87 nucleus
Norita Kawanaka, Hiroshi Nagai, Yutaka Fujita
We analyzed the archival ALMA data of the nuclear region of M87 and evaluate the molecular gas content from the CO(2--1) absorption line. We found an enigmatic variability in the a…
Precision spectral measurements of Chromium and Titanium from 10 to 250 GeV and sub-Iron to Iron ratio with the Calorimetric Electron Telescope on the ISS
O. Adriani, Y. Akaike, K. Asano +77
The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray (CR) iron and sub-iron events over a…