Search Publications
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…
X-ray flux and spectral variability of the blazar OJ 287 with Suzaku
Gupta, Alok C.; Wiita, Paul J.; Xu, Haiguang +4 more
We present analyses of Suzaku XIS light curves and spectra of the BL Lac object OJ 287 with observations positioned primarily around proposed recurrent optical outbursts. The first two observations were performed in 2007 April 10-13 (epoch 1) and 2007 November 7-9 (epoch 2) that, respectively, correspond to a low and a high optical state and which…
Multi-epoch X-ray spectral analysis of Centaurus A: Revealing new constraints on iron emission line origins
Tanimoto, Atsushi; Bamba, Aya; Hagino, Kouichi +3 more
We conduct X-ray reverberation mapping and spectral analysis of the radio galaxy Centaurus A to uncover its central structure. We compare the light curve of the hard X-ray continuum from Swift Burst Alert Telescope observations with that of the Fe K
Separating the Spectral Counterparts in NGC 1275/Perseus Cluster in X-Rays
Fedorova, Elena; Zadorozhna, Lidiia; Tugay, Anatolii +3 more
We present a model-independent method for separating the spectral counterparts of the active galactic nucleus (AGN) NGC 1275 from the surrounding emission of the Perseus cluster, as observed by Suzaku/XIS cameras. The Perseus cluster emission extends to higher energies than typically observed in AGN environments, reaching up to 9–10 keV. This nece…
Suzaku observation of an iron K-shell line in the spiral galaxy NGC 6946
Yamauchi, Shigeo; Inaba, Azusa; Anraku, Yumiko
An emission line at ~6.7 keV is attributable to an He-like iron K-shell transition, which indicates existence of a thin thermal plasma with a temperature of several keV. Using Suzaku archival data, we searched for the iron K-line from the spiral galaxy NGC 6946, and found it at 6.68 ± 0.07 keV at the 3.1σ level in the central $r\le {2.^{\prime }5}…