Search Publications
A Multi-faceted View of the X-Ray Spectral Variability in Seyfert Galaxy Ark 120
Kang, Jia-Lai; Wang, Jun-Xian; Ren, Lu-Xin
Utilizing a range of techniques including multi-band light curves, softness ratio analysis, structure functions, rms spectra, cross-correlation functions, and ratios of spectra from different intervals, we present a comprehensive study of the complex X-ray spectral variability in Seyfert 1 galaxy Ark 120, through re-analyzing its six XMM-Newton ob…
Long Term X-Ray Spectral Variations of the Seyfert-1 Galaxy Mrk 279
Jeena, K.; Misra, Ranjeev; Akhila, K. +1 more
We present the results from a long term X-ray analysis of Mrk 279 during the period 2018–2020. We use data from multiple missions – AstroSat, NuSTAR and XMM-Newton, for the purpose. The X-ray spectrum can be modeled as a double Comptonization along with the presence of neutral Fe Kα line emission, at all epochs. We determined the source's X-ray fl…
A Possible X-ray Quasi-periodic Oscillation in the Narrow-line Seyfert 1 Galaxy Mrk 142
Zhong, Xiao-Gu; Wang, Jian-Cheng; Chen, Yong-Yun +1 more
A possible quasi-periodic oscillation (QPO) at frequency 7.045 × 10‑5 Hz is found in the narrow-line Seyfert 1 galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April 11. We find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by…
Possible Detection of a Flare-associated Coronal Mass Ejection on an M-dwarf
Wang, J.
We here report a probable detection of a stellar coronal mass ejection (CME) in active M dwarf KIC 8093473 by performing an analysis on its time resolved X-ray spectra observed by the XMM-Newton satellite. Compared to the value at the quiescent state and the interstellar one, our spectral modeling returns a marginal (and probably evolving) excess …
NGC 4117: A New Compton-thick AGN Revealed by Broadband X-Ray Spectral Analysis
Mohanadas, Pavithra; Annuar, Adlyka
In this paper, we present the broadband (0.5-195 keV) X-ray spectral analysis for one of the newly detected AGNs in the Swift-BAT 105 month Hard X-ray Survey Catalog, NGC 4117. According to our ongoing research on low luminosity AGNs from the Swift-BAT 105 month catalog, we examine whether they are indeed low luminosity or heavily obscured AGNs. O…
Possible Origin of a Newly Discovered GeV Gamma-Ray Source Fermi J1242.5+3236
Mo, Xiu-Rong; Luo, Ming-Hong; Tan, Hong-Bin +2 more
Based on the first 13.4 yr of Fermi science data in the energy range from 300 MeV to 500 GeV, we discovered a bright GeV gamma-ray source with a ~5.64σ detection, named Fermi J1242.5+3236, which has an offset of about 0.°0996 from a nearby star-forming galaxy NGC 4631. When using the 12 yr' data, the detection significance of Fermi J1242.5+3236 is…
Optical and X-Ray Studies of Marginal Contact Binary RW Dor Using TESS and XMM-Newton Observatories
Sriram, K.; Mamatha Rani, G.
Marginal short-period contact binaries are important to understand as they pose a different physical scenario than the predicted theoretical model based on the thermal relaxation oscillation mechanism due to their shallow degree of contact. Here we present the optical and X-ray studies of a contact binary source RW Dor using the Transiting Exoplan…
Analysis of X-Ray Emission from OB Stars. IV. About X-Ray Emission from Inhomogeneous Winds of OB Stars
Ryspaeva, Elizaveta; Kholtygin, Alexander
We study the origin of X-ray emission from OB stars due to collisions of stellar winds and/or inhomogeneities in the winds. The low-resolution X-ray spectra of a big sample of OB stars were fitted by both the stationary APEC/MEKAL models and by this model with an additional PSHOCK component describing the nonstationary X-ray emission. These spectr…
An Improved Pair Method to Probe the Dust Extinction Law
Gao, Jian; Ren, Yi; Wang, Yuxi +1 more
Dust extinction law is crucial to recover the intrinsic energy distribution of celestial objects and infer the characteristics of interstellar dust. Based on the traditional pair method, an improved pair method is proposed to model the dust extinguished spectral energy distribution (SED) of an individual star. Instead of the mathematically paramet…
Probing the Variation of Reverberation Lags along with X-Ray Flux in the AGN Mrk 704
Sriram, K.; Choi, C. S.; Agrawal, Vivek K. +2 more
Understanding the variation of lags with respect to the X-ray flux is important to explore the geometry of the inner region of the accretion disk in AGNs. We performed frequency-lag, energy-lag and spectral studies for two sets of observations, in order to investigate the variations in lags with respect to X-ray flux in the AGN source Mrk 704 usin…