2,938 research outputs found
Probing the Cosmic X-ray and MeV Gamma-ray Background Radiation through the Anisotropy
While the cosmic soft X-ray background is very likely to originate from
individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV
gamma-ray background is not fully understood. It is expected that Seyferts
including Compton thick population may explain the cosmic hard X-ray
background. At MeV energy range, Seyferts having non-thermal electrons in
coronae above accretion disks or MeV blazars may explain the background
radiation. We propose that future measurements of the angular power spectra of
anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to
deciphering these backgrounds and the evolution of active galactic nuclei
(AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of
AGNs exists. We show that e-ROSITA will clearly detect the correlation signal
of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to
measure the bias parameter of AGNs at both bands. Once the future hard X-ray
all sky satellites achieve the sensitivity better than 10^{-12} erg/cm^2/s at
10-30 keV or 30-50 keV - although this is beyond the sensitivities of current
hard X-ray all sky monitors - angular power spectra will allow us to
independently investigate the fraction of Compton-thick AGNs in all Seyferts.
We also find that the expected angular power spectra of Seyferts and blazars in
the MeV range are different by about an order of magnitude, where the Poisson
term, so-called shot noise, is dominant. Current and future MeV instruments
will clearly disentangle the origin of the MeV gamma-ray background through the
angular power spectrum.Comment: 14 pages, 8 figures, accepted for publication in Ap
Probing the birth of fast rotating magnetars through high-energy neutrinos
We investigate the high-energy neutrino emission expected from newly born
magnetars surrounded by their stellar ejecta. Protons might be accelerated up
to 0.1-100 EeV energies possibly by, e.g., the wave dissipation in the winds,
leading to hadronic interactions in the stellar ejecta. The resulting PeV-EeV
neutrinos can be detected by IceCube/KM3Net with a typical peak time scale of a
few days after the birth of magnetars, making the characteristic soft-hard-soft
behavior. Detections would be important as a clue to the formation mechanism of
magnetars, although there are ambiguities coming from uncertainties of several
parameters such as velocity of the ejecta. Non-detections would also lead to
useful constraints on the scenario.Comment: 5 pages, 3 figures, accepted for publication in PR
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