Search Publications
Revisiting the Suzaku spectrum of the Galactic SNR W 49B: Non-detection of iron K-shell charge-exchange emission and refined ejecta-mass ratios of iron-group elements
Sato, Toshiki; Sawada, Makoto; Maeda, Keiichi +1 more
The origin of the recombining plasma in several Galactic SNRs has been debated. A plausible mechanism would be a rapid cooling in the past, by either an adiabatic or a conductive process. A recent spectral study of W 49B reported a possible charge-exchange emission due to collisions between the shock-heated ejecta and cold clouds, which could be d…
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…
An X-ray study of changing-look active galactic nuclei
Titarchuk, Lev; Seifina, Elena; Mishin, Egor
A significant number of changing-look active galactic nuclei (CL AGNs) have been identified to date. In this work, we study what happens to the X-ray spectrum during CL events. We use the example of the nearby CL Seyfert named NGC 1566, which has been observed by Swift, NuSTAR, XMM-Newton, and Suzaku. We applied the Comptonization model to describ…
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 …
The X-ray rise and fall of the symbiotic recurrent nova system T CrB
Sacchi, Andrea; Toalá, Jesús A.; González-Martín, Omaira +1 more
We present the analysis of publicly available NuSTAR, Suzaku, and XMM-Newton observations of the symbiotic recurrent nova T CrB covering the 2006.77-2022.66 yr period. The X-ray spectra are analysed by adopting a model that includes a reflection component produced by the presence of a disc that mimics the accretion disc and the immediate surroundi…
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…
Long-term X-ray temporal and spectral study of a Seyfert galaxy Mrk 6
Naik, Sachindra; Jana, Arghajit; Kumari, Neeraj +3 more
We present a long-term X-ray study of a nearby Active Galactic Nucleus Mrk 6, utilizing observations from XMM-Newton, Suzaku, Swift, and NuSTAR observatories, spanning 22 years from 2001 to 2022. From timing analysis, we estimated variance, normalized variance, and fractional rms amplitude in different energy bands.The temporal study shows fractio…
Detection of the neutral iron line from the supernova remnant W 49 B with Suzaku
Katsuda, Satoru; Nobukawa, Masayoshi; Nobukawa, Kumiko K. +2 more
Recent studies of supernova remnants (SNRs) have revealed that some SNRs exhibit a neutral iron line emission at 6.4 keV. This line has been proposed to originate from the interaction of high-energy particles formed in the SNR shell with the surrounding cold matter. We searched for the neutral iron line emission in the SNR W 49 B. Significant dete…
Observational clues to the magnetic evolution of magnetars
Enoto, Teruaki; Makishima, Kazuo; Uchida, Nagomi
Utilizing four archival X-ray data sets taken with the Hard X-ray Detector onboard Suzaku, timing studies were performed on three magnetars, 1E 1841-045 (observed in 2006), SGR 0501+4516 (2008), and 1RXS J170849.0-400910 (2009 and 2010). Their pulsations were reconfirmed, typically in an energy range of 12-50 keV. The 11.783 s pulses of 1E 1841-04…