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…
Enrichment of the Hot Intracluster Medium: Observations
Yamaguchi, H.; Simionescu, A.; Kaastra, J. S. +7 more
Four decades ago, the firm detection of an Fe-K emission feature in the X-ray spectrum of the Perseus cluster revealed the presence of iron in its hot intracluster medium (ICM). With more advanced missions successfully launched over the last 20 years, this discovery has been extended to many other metals and to the hot atmospheres of many other ga…
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…
Super-Eddington accretion on to the neutron star NGC 7793 P13: Broad-band X-ray spectroscopy and ultraluminous X-ray sources
Harrison, F. A.; Ptak, A.; Stern, D. +8 more
We present a detailed, broad-band X-ray spectral analysis of the ultraluminous X-ray source (ULX) pulsar NGC 7793 P13, a known super-Eddington source, utilizing data from the XMM-Newton, NuSTAR and Chandra observatories. The broad-band XMM-Newton+NuSTAR spectrum of P13 is qualitatively similar to the rest of the ULX sample with broad-band coverage…
X-Ray and Gamma-Ray Observations of the Fermi Bubbles and NPS/Loop I Structures
Nakashima, Shinya; Inoue, Yoshiyuki; Kataoka, Jun +3 more
The Fermi bubbles were possibly created by large injections of energy into the Galactic Center (GC), either by an active galactic nucleus (AGN) or by nuclear starburst more than ~10 Myr ago. However, the origin of the diffuse gamma-ray emission associated with Loop I, a radio continuum loop spanning across 100° on the sky, is still being debated. …
X-ray study of the double radio relic Abell 3376 with Suzaku
Urdampilleta, I.; Kaastra, J. S.; Mernier, F. +5 more
We present an X-ray spectral analysis of the nearby double radio relic merging cluster Abell 3376 (z = 0.046), observed with the Suzaku XIS instrument. These deep (∼360 ks) observations cover the entire double relic region in the outskirts of the cluster. These diffuse radio structures are amongst the largest and arc-shaped relics observed in comb…
Multiple cyclotron line-forming regions in GX 301-2
Pottschmidt, K.; Natalucci, L.; Kretschmar, P. +6 more
We present two observations of the high-mass X-ray binary GX 301-2 with NuSTAR, taken at different orbital phases and different luminosities. We find that the continuum is well described by typical phenomenological models, like a very strongly absorbed NPEX model. However, for a statistically acceptable description of the hard X-ray spectrum we re…
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 …