Search Publications
Alternative Explanations for Extreme Supersolar Iron Abundances Inferred from the Energy Spectrum of Cygnus X-1
Gandhi, Poshak; Yamaoka, Kazutaka; Fürst, Felix +11 more
Here we study a 1-200 keV energy spectrum of the black hole binary Cygnus X-1 taken with NuSTAR and Suzaku. This is the first report of a NuSTAR observation of Cyg X-1 in the intermediate state, and the observation was taken during the part of the binary orbit where absorption due to the companion’s stellar wind is minimal. The spectrum includes a…
Spatial Distribution of the Milky Way Hot Gaseous Halo Constrained by Suzaku X-Ray Observations
Nakashima, Shinya; Inoue, Yoshiyuki; Kataoka, Jun +3 more
The formation mechanism of the hot gaseous halo associated with the Milky Way is still under debate. We report new observational constraints on the gaseous halo using 107 lines of sight of the Suzaku X-ray observations at 75° < l < 285° and | b| > 15^\circ with a total exposure of 6.4 Ms. The gaseous halo spectra are represented by a sing…
Evidence for a Neutral Iron Line Generated by MeV Protons from Supernova Remnants Interacting with Molecular Clouds
Koyama, Katsuji; Uchida, Hiroyuki; Nobukawa, Masayoshi +6 more
Supernova remnants (SNRs) have been prime candidates for Galactic cosmic-ray accelerators. When low-energy cosmic-ray protons (LECRp) collide with interstellar gas, they ionize neutral iron atoms and emit the neutral iron line (Fe I Kα) at 6.40 keV. We search for the iron K-shell line in seven SNRs from the Suzaku archive data of the Galactic plan…
Suzaku Observations of Heavily Obscured (Compton-thick) Active Galactic Nuclei Selected by the Swift/BAT Hard X-Ray Survey
Tanimoto, Atsushi; Ueda, Yoshihiro; Kawamuro, Taiki +3 more
We present a uniform broadband X-ray (0.5-100.0 keV) spectral analysis of 12 Swift/Burst Alert Telescope selected Compton-thick ({log}{N}{{H}}/{{cm}}-2≥slant 24) active galactic nuclei (CTAGNs) observed with Suzaku. The Suzaku data of three objects are published here for the first time. We fit the Suzaku and Swift spectra wit…
The Transition from Young to Middle-aged Supernova Remnants: Thermal and Nonthermal Aspects of SNR N132D
Miller, Eric D.; Katsuda, Satoru; Terada, Yukikatsu +8 more
Supernova remnants (SNRs) are the primary candidate of Galactic cosmic-ray accelerators. It is still an open issue when and how young SNRs, which typically exhibit strong synchrotron X-rays and GeV and TeV gamma rays, undergo the state transition to middle-aged SNRs dominated by thermal X-rays and GeV gamma rays. SNR N132D in the Large Magellanic …
X-Ray and GeV Gamma-Ray Variability of the Radio Galaxy NGC 1275
Fukazawa, Yasushi; Itoh, Ryosuke; Takahashi, Hiromitsu +6 more
We analyzed Suzaku/XIS data (2006-2015) and Fermi/LAT data (2008-2015) of the gamma-ray emitting radio galaxy NGC 1275. Correlated brightening of the nucleus in both the X-ray and GeV gamma-ray energy bands was found for the period 2013-2015. This is the first evidence of correlated variability between these two energy bands for NGC 1275. We also …
Chandrasekhar and Sub-Chandrasekhar Models for the X-Ray Emission of Type Ia Supernova Remnants. I. Bulk Properties
Yamaguchi, Hiroya; Auchettl, Katie; Badenes, Carles +9 more
Type Ia supernovae originate from the explosion of carbon-oxygen white dwarfs in binary systems, but the exact nature of their progenitors remains elusive. The bulk properties of Type Ia supernova remnants, such as the radius and the centroid energy of the Fe Kα blend in the X-ray spectrum, are determined by the properties of the supernova ejecta …
An Empirical Correlation of T max-M WD of Dwarf Novae and the Average White Dwarf Mass in Cataclysmic Variables in the Galactic Bulge
Li, Xiang-Dong; Bao, Tong; Xu, Xiao-jie +4 more
The mean white dwarf (WD) mass in the Galactic bulge cataclysmic variables (CVs) was measured by applying the shock temperature-WD mass correlation of magnetic cataclysmic variables (mCVs) to the Galactic bulge X-ray emission (GBXE) spectra. However, the resulting mean WD mass is lower than that of the local CVs. This discrepancy could be explaine…
Diffuse X-Ray Emission from the Northern Arc of Loop I Observed with Suzaku
Nakashima, Shinya; Inoue, Yoshiyuki; Kataoka, Jun +4 more
After discovery of the Fermi bubbles, giant structures observed from radio to X-ray monitoring have been widely discussed as possible evidence of past activities in the Galactic center (GC). We report here on the analysis of all the Suzaku archival data pointing around the giant-scale Loop I arc. The diffuse X-ray emission from the northern Loop I…
X-Ray Observations of Magnetar SGR 0501+4516 from Outburst to Quiescence
Ng, C. -Y.; Mong, Y. -L.
Magnetars are neutron stars having extreme magnetic field strengths. Study of their emission properties in quiescent state can help understand effects of a strong magnetic field on neutron stars. SGR 0501+4516 is a magnetar that was discovered in 2008 during an outburst, which has recently returned to quiescence. We report its spectral and timing …