A5087675760- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Particle Detector Development and Performance
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Nuclear Physics and Applications
- Dark Matter and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Radiation Detection and Scintillator Technologies
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Advanced Semiconductor Detectors and Materials
- Advanced X-ray and CT Imaging
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Calibration and Measurement Techniques
- Distributed and Parallel Computing Systems
- Geophysics and Gravity Measurements
- Radiation Therapy and Dosimetry
- Atomic and Subatomic Physics Research
- Spacecraft Design and Technology
Hiroshima University of Economics
2024
Hiroshima University
2014-2023
Eötvös Loránd University
2019-2022
Konkoly Observatory
2019-2022
Hungarian Academy of Sciences
2019-2022
Research Centre for Astronomy and Earth Sciences
2020-2021
University of Palermo
2020-2021
Trieste Astronomical Observatory
2021
Camelot Biomedical Systems (Italy)
2021
Czech Academy of Sciences, Institute of Physics
2021
We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because instrument does not have an onboard magnet, we distinguish two species by exploiting Earth's shadow, which is offset in opposite directions for charges due to magnetic field. estimate subtract proton background using different methods that produce consistent results. report electron-only spectrum, positron-only fraction between 20 GeV 200 GeV. confirm rises energy 20-100 range. The...
The Hard X-ray Detector (HXD) on board Suzaku covers a wide energy range from 10 keV to 600 by combination of silicon PIN diodes and GSO scintillators. HXD is designed achieve an extremely low in-orbit back ground based new techniques, including the concept well-type active shield counter. With effective area 142 cm^2 at 20 273 cm2 150 keV, background level sea reached ~1x10^{-5} cts s^{-1} cm^{-2} keV^{-1} 30 for PI N diodes, ~2x10^{-5} 100 ~7x10^{-6} 200 phoswich Tight shielding results in...
The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of emission towards Galactic centre (GC) in high-energy gamma-rays. This paper describes analysis data taken during first 62 months mission energy range 1-100 GeV from a $15^\circ \times 15^\circ$ region about direction GC, and implications for interstellar emissions produced by cosmic ray (CR) particles interacting with gas radiation fields inner Galaxy point sources detected. Specialised models (IEMs) are...
Abstract The in-orbit performance and calibration of the Hard X-ray Detector (HXD) on board astronomy satellite Suzaku are described. Its basic performances, including a wide energy bandpass 10–600 keV, resolutions $\sim 4 \,\mathrm{keV}$ (FWHM) at 40 keV 11\%$ 511 high background rejection efficiency, have been confirmed by extensive calibrations. long-term gains PIN-Si diodes stable within 1% for half year, those scintillators decreased 5–20%. residual non-X-ray HXD is lowest among past...
The light emitted by stars and accreting compact objects through the history of Universe is encoded in intensity extragalactic background (EBL). Knowledge EBL important to understand nature star formation galaxy evolution, but direct measurements are lim- ited Galactic other foreground emissions. Here we report an absorption feature seen combined spectra a sample gamma-ray blazars out redshift z$\sim$1.6. This caused attenuation gamma rays at optical UV frequencies, allowed us measure flux...
Abstract Suzaku Hard X-ray Detector (HXD) achieved the lowest background level than any other previously or currently operational missions sensitive in energy range of 10–600 keV, by utilizing PIN photodiodes and GSO scintillators mounted BGO active shields to reject particle Compton-scattered events as much possible. Because it does not have an imaging capability nor rocking mode for monitor, sensitivity is limited reproducibility non (NXB) model. We modeled HXD NXB, which varies with time...
Nearby clusters and groups of galaxies are potentially bright sources high-energy gamma-ray emission resulting from the pair-annihilation dark matter particles. However, no significant has been detected so far in first 11 months observations with Fermi Large Area Telescope. We interpret this non-detection terms constraints on particle properties. In particular for leptonic annihilation final states masses greater than ~200 GeV, inverse Compton scattering CMB photons is expected to dominate...
GRB110721A was observed by the Fermi Gamma-ray Space Telescope using its two instruments Large Area (LAT) and Burst Monitor (GBM). The burst consisted of one major emission episode which lasted for ~24.5 seconds (in GBM) had a peak flux 5.7\pm0.2 x 10^{-5} erg/s/cm^2. time-resolved spectrum is best modeled with combination Band function blackbody spectrum. energy component initially 15\pm2 MeV, highest value ever detected in GRB. This measurement made possible combining GBM/BGO data LAT Low...
The Fermi Large Area Telescope (LAT) observed two bright X-class solar flares on 2012 March 7, and detected gamma-rays up to 4 GeV. We both during the impulsive temporally-extended emission phases, with above 100 MeV lasting for approximately 20 hours. Accurate localization of gamma-ray production site(s) coincide active region from which X-ray emissions associated these originated. Our analysis >100 shows a relatively rapid monotonic decrease in flux first hour phase, much slower, almost...
We present the detections of 19 solar flares detected in high-energy gamma rays (above 100 MeV) with Fermi Large Area Telescope (LAT) during its first four years operation. Interestingly, all are associated fairly fast Coronal Mass Ejections (CMEs) and not powerful X-ray flares. then describe detailed temporal, spatial spectral characteristics two long-lasting events: 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying gamma-ray emission over 13 hours, June M2.5...
Suzaku has, for the first time, enabled hard X-ray variability of Seyfert 1 galaxy MCG-6-30-15 to be measured. The in 14-45 keV band, which is dominated by a strong reflection hump, quenched relative that at few keV. This directly demonstrates whole spectrum much less variable than power-law continuum. broadband spectral can decomposed into two components - highly and constant as previously inferred from other observations 2-10 band. high iron abundance give rise broad line, requires inner...
We systematically analyzed the high-quality Suzaku data of 88 Seyfert galaxies. obtained a clear relation between absorption column density and equivalent width 6.4 keV line above 10$^{23}$ cm$^{-2}$, suggesting wide-ranging $10^{23-24.5}$ cm$^{-2}$ with similar solid Fe abundance 0.7--1.3 solar for 2 The EW 1 galaxies are typically 40--120 eV, existence Compton-thick matter like torus $>10^{23}$ angle $(0.15-0.4)*4pi$, no difference neutral is visible An absorber lower $10^{21-23}$...
We present a generalized analytic formalism for the inverse Compton X-ray emission from hydrogen-poor supernovae and apply this framework to SN 2011fe using Swift X-Ray Telescope (XRT), UVOT, Chandra observations. characterize optical properties of in bands find them be broadly consistent with "normal" Ia, however, no source is detected by either XRT or Chandra. constrain progenitor system mass-loss rate (3σ c.l.) wind velocity vw = 100 km s−1. Our result rules out symbiotic binary...
ABSTRACT We report the Fermi Large Area Telescope detection of extended γ -ray emission from lobes radio galaxy Fornax A using 6.1 years Pass 8 data. After Centaurus A, this is now second example an source attributed to a galaxy. Both flat disk morphology and following were preferred over point-source description, core contribution was constrained be <?CDATA $\lt 14$?> % total flux. alignment elongation with demonstrated by rotating template. found no significant evidence for variability on...
One of the most prominent, yet controversial associations derived from ensemble prompt-phase observations gamma-ray bursts (GRBs) is apparent correlation in source frame between peak energy (Epeak) νF(ν) spectrum and isotropic radiated energy, Eiso. Since GRBs have Epeak above range (15–150 keV) Burst Alert Telescope (BAT) on Swift, determining accurate values for large numbers Swift has been difficult. However, by combining data Swift/BAT Suzaku Wide-band All-Sky Monitor (WAM), which covers...
We present a detailed analysis of the GeV gamma-ray emission toward supernova remnant (SNR) G8.7−0.1 with Large Area Telescope (LAT) on board Fermi Gamma-ray Space Telescope. An investigation relationship between and TeV unidentified source HESS J1804−216 provides us an important clue diffusion process cosmic rays if particle acceleration operates in SNR. The is extended most positional coincidence SNR lesser part located outside western boundary G8.7−0.1. region overlaps spatially connected...
The GOES M2-class solar flare, SOL2010-06-12T00:57, was modest in many respects yet exhibited remarkable acceleration of energetic particles. flare produced an ~50 s impulsive burst hard X- and \gamma-ray emission up to at least 400 MeV observed by the Fermi GBM LAT experiments. remarkably similar X-ray high-energy time profiles suggest that most particles were accelerated energies >300 with a delay ~10 from mildly relativistic electrons, but some reached these as little ~3 s. line fluence...
The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space routinely detects highly dust-absorbed, reddened, and MeV-peaked flat spectrum radio quasar PKS 1830-211 (z=2.507). Its apparent isotropic gamma-ray luminosity (E>100 MeV) averaged over $\sim$ 3 years of observations peaking 2010 October 14/15 at 2.9 X 10^{50} erg s^{-1}, makes it among brightest high-redshift blazars. No published model with a single lens can account for all observed characteristics this complex system. Based...
The brightest gamma-ray burst ever observed, long-duration GRB 221009A, was detected by GRBAlpha nano-satellite without saturation. We present light curves of the prompt emission in 13 energy bands, from 80 keV to 950 keV, and perform a spectral analysis calculate peak flux isotropic-equivalent luminosity. Since satellite's attitude information is not available for time this GRB, more than 200 incident directions were probed order find median luminosity its systematic uncertainty. found that...
The hard X-ray detector (HXD-II) is one of the three scientific instruments onboard Japanese astronomy satellite Astro-E2 scheduled to be launched in 2005. This mission very unique a point having lower background than any other past missions 10-600 keV range. In HXD-II, large and thick BGO crystals are used as active shields for particle gamma-ray main detector. They have wide field view ~2pi effective area 400 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
We report on a systematic investigation of the gamma-ray properties 120 hard X-ray-selected Seyfert galaxies classified as `radio-quiet' objects, utilizing three-year accumulation Fermi-LAT data. Our sample is selected using Swift-BAT 58-month catalog, restricting analysis to bright sources with average X-ray fluxes F(14-195 keV) > 2.5x10-11 erg cm-2 s-1 at high Galactic latitudes (|b|>10 deg). In order remove `radio-loud' objects from sample, we use `hard radio loudness parameter', Rrx,...
We construct an X-ray spectral model of reprocessing by a torus in active galactic nucleus (AGN) with Monte Carlo simulation framework MONACO. Two geometries smooth and clumpy cases are considered compared. In order to reproduce Compton shoulder accurately, MONACO includes not only free electron scattering but also bound scattering. Raman Reyleigh treated, cross sections dependent on chemical states hydrogen helium included. Doppler broadening turbulence velocity can be implemented. Our...
ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage and exquisite resolution. The Soft Gamma-ray Detector (SGD) one of will feature wide band (40-600 keV) at a background level 10 times better than current on orbit. SGD complimentary ASTRO-H's Hard Imager covering range 5-80 keV. achieves low by combining Compton camera scheme narrow field-of-view active shield where kinematics utilized reject backgrounds. in realized as hybrid...
The fastest-rotating magnetar 1E 1547.0-5408 was observed in broad-band X-rays with Suzaku for 33 ks on 2009 January 28-29, 7 days after the onset of its latest bursting activity. After removing burst events, absorption-uncorrected 2-10 keV flux persistent emission measured XIS as 5.7e-11 ergs cm-2 s-1, which is 1-2 orders magnitude higher than 2006 and 2007 when source less active. also detected significantly HXD >10 up to at least ~110 keV, an even 1.3e-10 s-1 20-100 keV. pulsation 70 a...
Abstract The Suzaku Wide-band All-sky Monitor (WAM) consists of thick BGO anti-coincidence shields the Hard X-ray Detectors (HXD). It views about half sky and has a geometrical area 800 cm$^2$ per sdide an effective 400 cm$^2$, even at 1 MeV. Hence, WAM can provide unique opportunities to detect high-energy emission from GRBs solar flares in sub-MeV MeV range. detected more than 100 since its launch. This paper describes in-flight performance HXD/WAM during initial two years operations,...