Search Publications
Suzaku Observations of the Cold Front in A3667: A Nonequilibrium Ionization State of the Intracluster Medium
Kohmura, Takayoshi; Uchida, Yuusuke; Shishido, Mona
We present a systematic study of the thermodynamic properties of the intracluster medium (ICM), including the plasma conditions in the ICM, in the merging galaxy cluster A3667 using Suzaku. We analyze the X-ray spectra of the ICM between the northwestern and the southeastern radio relics across a prominent cold front in A3667 to search for the ICM…
Pulse-profile Modeling and Spin–Orbit Alignment in a Suzaku Sample of Accreting X-Ray Binary Pulsars
Paul, Biswajit; Laycock, Silas G. T.; Pradhan, Pragati +2 more
We report pulse-profile modeling of a sample of 23 X-ray binary pulsars observed with the Suzaku X-ray satellite. These pulsars have spin periods ranging from 0.7 to 9400 s, and their X-ray emission is powered by the accretion from their stellar companions. We fitted each individual pulse profile with the Polestar geometric model, which accounts f…
Black Hole Spin Measurements in LMC X-1 and Cyg X-1 Are Highly Model Dependent
Zdziarski, Andrzej A.; Szanecki, Michał; Dewangan, Gulab +4 more
The black hole spin parameter, a *, was measured to be close to its maximum value of 1 in many accreting X-ray binaries. In particular, a * ≳ 0.9 was found in a number of studies of LMC X-1. These measurements were claimed to take into account both statistical and systematic uncertainties. We perform new measurements using a …
Discovery of a Second Eclipsing, Bursting Neutron Star Low-mass X-Ray Binary in the Globular Cluster Terzan 6
Bahramian, Arash; Homan, Jeroen; Heinke, Craig O. +4 more
We have analyzed Chandra and Suzaku observations of the globular cluster Terzan 6, made when the recurrent transient GRS 1747–312 was in quiescence. Our analysis reveals the presence of a second eclipsing, bursting neutron star low-mass X-ray binary in the central regions of the cluster, in addition to GRS 1747–312. The new source, which we name T…
Possible Supercritical Accretion on the Ultraluminous X-Ray Source in the Metal-poor Galaxy I Zw 18
Yoneyama, Tomokage; Matsumoto, Hironori; Noda, Hirofumi +2 more
We present an analysis of X-ray observations of the ultraluminous X-ray source (ULX) in I Zw 18 based on archival data taken with Chandra, XMM-Newton, and Suzaku. This ULX is considered to be an intermediate-mass black hole candidate simply because it is in the lowest-metallicity environment among ULXs, where the formation of heavy black holes is …
Further Evidence for the 9 s Pulsation in LS 5039 from NuSTAR and ASCA
Enoto, Teruaki; Makishima, Kazuo; Takahashi, Tadayuki +2 more
The present study aims to reinforce the evidence for the ~9 s pulsation in the gamma-ray binary LS 5039, derived from a Suzaku observation in 2007 and a NuSTAR observation in 2016. Through a reanalysis of the NuSTAR data incorporating the orbital Doppler correction, the 9.0538 s pulsation was confirmed successfully even in the 3-10 keV range, wher…
New Constraints on the Spin of the Black Hole Cygnus X-1 and the Physical Properties of its Accretion Disk Corona
Krawczynski, H.; Beheshtipour, B.
We present a new analysis of NuSTAR and Suzaku observations of the black hole Cygnus X-1 in the intermediate state. The analysis is performed using kerrC, a new model for analyzing spectral and spectropolarimetric X-ray observations of black holes. kerrC builds on a large library of simulated black holes in X-ray binaries. The model accounts for t…
RXTE Observation of the Nonthermal Emission from the Early Stage Merger in A1750
Henriksen, Mark J.
We make the first observation-based calculation of the energy that goes into cosmic ray protons versus cosmic ray electrons in shock acceleration during structure formation. We find a ratio of energy in cosmic ray protons to energy in cosmic ray electrons of 0.86. This value, calculated from the nonthermal X-ray component reported here from RTXE a…
Discovery of 40.5 ks Hard X-Ray Pulse-phase Modulations from SGR 1900+14
Suzuki, H.; Enoto, T.; Makishima, K. +4 more
X-ray timing properties of the magnetar SGR 1900+14 were studied, using the data taken with Suzaku in 2009 and NuSTAR in 2016, for a time lapse of 114 and 242 ks, respectively. On both occasions, the object exhibited the characteristic two-component spectrum. The soft component, dominant in energies below ~5 keV, showed a regular pulsation, with a…
Are Compton-thin AGNs Globally Compton Thin?
Yukita, M.; Ptak, A.; LaMassa, S. +2 more
We select eight nearby active galactic nuclei (AGNs) which, based on previous work, appear to be Compton-thin in the line of sight. We model with MYTORUS their broadband X-ray spectra from 20 individual observations with Suzaku, accounting self-consistently for Fe Kα line emission, as well as direct and scattered continuum from matter with finite …