Search Publications
SGRs and AXPs as Rotation-Powered Massive White Dwarfs
Malheiro, Manuel; Rueda, Jorge A.; Ruffini, Remo
SGR 0418+5729 is a ``Rosetta Stone'' for deciphering the energy source of Soft Gamma Ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs). We present a model based on canonical physics and astrophysics for SGRs and AXPs powered by massive highly magnetized rotating white dwarfs (WDs), in total analogy with pulsars powered by rotating neutron st…
Recombining Plasma and Hard X-Ray Filament in the Mixed-Morphology Supernova Remnant W 44
Yamaguchi, Hiroya; Uchida, Hiroyuki; Fukui, Yasuo +6 more
We report on new features of the typical mixed-morphology supernova remnant W 44. In X-ray spectra obtained with Suzaku, radiative recombination continua of highly ionized atoms were detected for the first time. The spectra are well reproduced by a thermal plasma in a recombining phase. The best-fit parameters suggest that the electron temperature…
X-Ray Observations of the Supernova Remnant W28 with Suzaku. I. Spectral Study of the Recombining Plasma
Koyama, Katsuji; Sawada, Makoto
We present Suzaku results of the mixed-morphology supernova remnant W 28. The X-ray spectra of the central region of W 28 exhibit many bright emission lines from highly ionized atoms. An optically thin thermal plasma in collisional ionization equilibrium, either of single temperature or multi temperatures, failed to reproduce the data with line-li…
X-Ray View of the Shock Front in the Merging Cluster Abell 3376 with Suzaku
Fukazawa, Yasushi; Nakazawa, Kazuhiro; Ohashi, Takaya +3 more
We report on a Suzaku measurement of the shock feature associated with the western radio relic in the merging cluster A 3376. The temperature profile is characterized by an almost flat radial shape with kT ∼ 4 keV within 0.5r200 and a rise by about 1 keV inside the radio relic. Across the relic region (0.6-0.8r200), the tempe…
Suzaku Observations of the Hydra A Cluster out to the Virial Radius
Sato, Kosuke; Fukazawa, Yasushi; Nakazawa, Kazuhiro +12 more
We report on Suzaku observations of the northern half of the Hydra A cluster out to ∼ 1.4 Mpc, reaching the virial radius. There are the first Suzaku observations of a medium-size (kT ∼ 3 keV) cluster out to the virial radius. Two observations were conducted, north-west and north-east offsets, which continue in a filament direction and a void dire…
Properties of the Intracluster Medium of Abell 3667 Observed with Suzaku XIS
Nakazawa, Kazuhiro; Ohashi, Takaya; Kaastra, Jelle +4 more
We observed the northwest region of the cluster of galaxies Abell 3667 with the Suzaku XIS instrument. The temperature and surface brightness of the intracluster medium were measured up to the virial radius (r200 ∼ 2.3 Mpc). The radial temperature profile is flatter than the average profile for other clusters until the radius reaches th…
Data-Oriented Diagnostics of Pileup Effects on the Suzaku XIS
Dotani, Tadayasu; Katsuda, Satoru; Enoto, Teruaki +11 more
We present the results of a systematic study of pileup phenomena seen in the X-ray Imaging Spectrometer, an X-ray CCD instrument, onboard the Suzaku observatory. Using a data set of observed sources in a wide range of brightness and spectral hardness, we characterized the pileup fraction, spectral hardening, and grade migration as a function of th…
Accretion Geometry of the Low-Mass X-Ray Binary Aquila X-1 in the Soft and Hard States
Makishima, Kazuo; Nakazawa, Kazuhiro; Takahashi, Hiromitsu +4 more
The neutron-star Low-Mass X-ray Binary Aquila X-1 was observed seven times in total with the Suzaku X-ray observatory from September 28 to October 30 in 2007, in the decaying phase of an outburst. In order to constrain the flux-dependent accretion geometry of this source over wider energy bands than employed in most previous studies, the present s…
A Variable Partial Covering Model for the Seyfert 1 Galaxy MCG -6-30-15
Ebisawa, Ken; Inoue, Hajime; Miyakawa, Takehiro
We propose a simple spectral model for the Seyfert 1 Galaxy MCG -6-30-15 that can explain most of the 1-40 keV spectral variation by a change of the partial covering fraction, similar to that proposed by Miller, Turner, and Reeves (2008, A&A, 483, 437). Our spectral model is composed of three continuum components: (1) a direct power-law compon…
Star Formation and AGN Activity in Galaxies Classified Using the 1.6 µm Bump and PAH Features at z = 0.4-2
Goto, Tomotsugu; Oyabu, Shinki; Ohyama, Youichi +17 more
We studied the star-formation and AGN activity of massive galaxies in the redshift range