Search Publications
Black hole spin of Cygnus X-1 determined from the softest state ever observed
Done, Chris; Fukazawa, Yasushi; Takahashi, Hiromitsu +3 more
We show the softest ever spectrum from Cyg X-1, detected in 2013 with Suzaku. This has the weakest high-energy Compton tail ever seen from this object, so should give the cleanest view of the underlying disk spectrum, and hence the best determination of black hole spin from disk continuum fitting. Using the standard model of a disk with simple non…
Suzaku observations of the outskirts of the galaxy cluster Abell 3395, including a filament toward Abell 3391
Ohashi, Takaya; Takizawa, Motokazu; Fujita, Yutaka +4 more
The results of Suzaku observations of the outskirts of Abell 3395, including a large-scale structure filament toward Abell 3391, are presented. We measured temperature and abundance distributions from the southern outskirt of A 3395 to the north at the virial radius, where a filament structure has been found in the former X-ray and Sunyaev-Zel'dov…
Localized recombining plasma in G166.0+4.3: A supernova remnant with an unusual morphology
Uchida, Hiroyuki; Nobukawa, Masayoshi; Tsuru, Takeshi Go +4 more
We observed the Galactic mixed-morphology supernova remnant G166.0+4.3 with Suzaku. The X-ray spectrum in the western part of the remnant is well represented by a one-component ionizing plasma model. The spectrum in the northeastern region can be explained by two components. One is an Fe-rich component with electron temperature kT_e = 0.87_{-0.03}…
A systematic X-ray study of the dwarf novae observed with Suzaku
Tsujimoto, Masahiro; Hayashi, Takayuki; Wada, Qazuya +1 more
X-ray behavior of the dwarf novae (DNe) outside the quiescent state has not been fully understood. We thus assembled 21 data sets of the 15 DNe observed by the Suzaku satellite by the end of 2013, which include spectra taken during not only the quiescence, but also the transitional, outburst, and super-outburst states. Starting with the traditiona…
Discovery of a keV-X-ray excess in RX J1856.5-3754
Yoneyama, Tomokage; Hayashida, Kiyoshi; Nakajima, Hiroshi +2 more
RX J1856.5-3754 is the brightest and nearest (∼120 pc) source among thermally emitting isolated neutron stars. Its spectra observed with XMM-Newton and Chandra satellites are well-fitted with the two-temperature (kT∞ ∼ 32 and 63 eV) blackbody model. Fitting ten sets of the data from Suzaku XIS 0, XIS 1, XIS 3, and XMM-Newton EPIC-pn wit…
Search for the warm-hot intergalactic medium around A 2744 using Suzaku
Finoguenov, Alexis; Akamatsu, Hiroki; Ota, Naomi +2 more
We present the results from Suzaku satellite observations of the surrounding region of a galaxy cluster, A 2744, at z = 0.3. To search for oxygen emission lines from the warm-hot intergalactic medium (WHIM), we analyzed X-ray spectra from two northeastern regions 2.2-3.3 and 3.3-4.4 Mpc from the center of the cluster, which offers the first test o…
A hard-to-soft state transition of Aquila X-1 observed with Suzaku
Yamaoka, Kazutaka; Makishima, Kazuo; Nakazawa, Kazuhiro +3 more
The recurrent soft X-ray transient Aquila X-1 was observed with Suzaku for a gross duration of 79.9 ks, on 2011 October 21 when the object was in a rising phase of an outburst. During the observation, the source exhibited a clear spectral transition from the hard state to the soft state, on a time scale of ∼30 ks. Across the transition, the 0.8-10…
Suzaku Wide-band All-sky Monitor (WAM) observations of GRBs and SGRs
Yamaoka, Kazutaka; Fukazawa, Yasushi; Hanabata, Yoshitaka +29 more
We will review results for gamma-ray bursts (GRBs) and soft gamma repeaters (SGRs), obtained from the Suzaku Wide-band All-sky Monitor (WAM) which operated for about 10 years from 2005 to 2015. The WAM is a BGO (bismuth germanate: Bi4Ge3O12) lateral shield for the Hard X-ray Detector (HXD), used mainly for rejectin…
Study of the progenitor of the magnetar 1E 2259+586 through Suzaku observations of the associated supernova remnant CTB 109
Enoto, Teruaki; Makishima, Kazuo; Nakano, Toshio +4 more
We present a study of the progenitor of the magnetar 1E 2259+586, from Suzaku observations of the associated supernova remnant CTB 109. The Suzaku spectra, either spatially integrated or spatially resolved, were successfully described by a two-component plasma model, which reconfirms a previous Chandra result on the northwestern part of this remna…
Suzaku observations of spectral variations of the ultra-luminous X-ray source Holmberg IX X-1
Makishima, Kazuo; Nakazawa, Kazuhiro; Kobayashi, Shogo B.
Observations of the ultra-luminous X-ray source (ULX) Holmberg IX X-1 were carried out with Suzaku twice, once on 2012 April 13 and then on 2012 October 24, with exposures of 180 ks and 217 ks, respectively. The source showed a hard power-law shaped spectrum with a mild cutoff at ∼8 keV, which is typical of ULXs when they are relatively dim. On bo…