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Browsing IIAP Publications by Title

Browsing IIAP Publications by Title

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  • Singh, V; Shastri, P (American Institute of Physics, 2008-08)
    We study the systematics of the X-ray emission from Seyfert nuclei in the frame work of unification. In order to do this rigorously a sample with types 1 and 2 matched in orientation-independent parameters is studied. The ...
  • Priyanka Rani; Stalin, C. S; Rakshit, S (Oxford University Press on behalf of the Royal Astronomical Society, 2017-04)
    We present results of a systematic study of flux variability on hourly time-scales in a large sample of active galactic nuclei (AGN) in the 3−79 keV band using data from Nuclear Spectroscopic Telescope Array. Our sample ...
  • Ghosh, K. K; Soundararajaperumal, S (University of Chicago Press, 1992-10)
    Results of the detailed X-ray (0.1-10 keV) spectral analysis of the Seyfert 1 galaxy, MGC 2-58-22, are presented based on the Exosat observations on 1984 November 16-26. X-ray spectra of this source were obtained from the ...
  • Pal, Indrani; Stalin, C. S; Chatterjee, Rwitika; Agrawal, Vivek K (Indian Academy of Sciences, 2023-12)
    X-ray polarimetry is a powerful tool to probe the geometry of the hot X-ray corona in active galactic nuclei (AGN). Here, we present our results on the characterisation of the X-ray polarization of the radio-quiet Seyfert-type ...
  • Ghosh, K. K; Soundararajaperumal, S (Blackwell Publishing, 1992-11)
    A spectra analysis of eight Seyfert galaxies shows that while seven have soft excesses in their spectra, with no low-energy absorption, ESO 140-G43 exhibits low energy absorption, and may have weak soft excess that is ...
  • Pal, Indrani; Stalin, C. S; Parker, M. L; Agrawal, Vivek K; Marchesi, S (Oxford University Press on behalf of Royal Astronomical Society, 2022-12)
    We present the timing and spectral analysis of the Compton Thick Seyfert 2 active galactic nuclei NGC 1068 observed using NuSTAR and XMM–Newton. In this work for the first time we calculated the coronal temperature (⁠kTekTe⁠) ...
  • Singh, V; Shastri, P; Risaliti, G (EDP Sciences, 2011-08)
    Context. The unification scheme of Seyfert galaxies predicts that the observed differences between types 1 and 2 Seyfert galaxies are solely due to the differing orientations of the toroidal-shaped obscuring material around ...
  • Ghosh, K. K; Soundararajaperumal, S (European Southern Observatory, 1993-06)
    X-ray (0.1-10 keV) spectra of NGC 4593 were obtained with EXOSAT on seven epochs between 1984 and 1986 using the low and medium energy detectors. Detailed results of the spectral analysis of the seven spectra (obtained ...
  • Ghosh, K. K; Sondararajaperumal, S (The American Astronomical Society, 1991-10)
    Results are presented of observations of the broad-line radio galaxy, 3C 390.3 that were made with Exosat on several occasions between 1984 and 1986 using low- (LE) and medium-energy (ME) detectors. Detailed findings of ...
  • Ghosh, K. K; Soundararajaperumal, S; Kalai Selvi, M; Sivarani, T (EDP Sciences, 1992-02)
    Results of the X-ray (0.1-10 keV) spectral analysis of the Seyfert I galaxy, NGC 3783, which was observed with EXOSAT on three epochs between 1983 and 1985, are presented here. No low energy absorption, intrinsic to the ...
  • Ghosh, K. K; Soundararajaperumal, S (EDP Sciences, 1991-12)
    A study of the X-ray (0.1-10 keV) spectrum from the radio-loud quasar, PKS 1217 + 023 is presented. This quasar was observed with Exosat on two epochs in January 29 and May 14, 1984. The data were obtained from the Exosat ...
  • Ghosh, K. K; Soundararajaperumal, S (Blackwell Publishing, 1992-02)
    Exosat observations (0.1-10 keV) of the radio-loud quasar 1928 + 73, which displays superluminal motion, were made at four epochs between 1983/283 and 1984/009, and spectra of this source are obtained from the Exosat ...
  • Mohan, Prashanth; Mangalam, A (IOP Publishing, 2014-08-20)
    We present theoretical models of X-ray variability attributable to orbital signatures from an accretion disk including emission region size, quasi-periodic oscillations (QPOs), and its quality factor Q, and the emergence ...
  • Chitnis, V. R; Pendharkar, J. K; Bose, D; Agrawal, V. K; Rao, A. R; Misra, R (Institute of Physics, 2009-06)
    We investigate the X-ray variability characteristics of hard X-ray-selected active galactic nuclei (AGNs)—based on Swift/Burst Alert Telescope—in the soft X-ray band using the Rossi X-ray Timing Explorer/All-Sky Monitor ...
  • Joshi, Ravi; Gopal Krishna; Yang, Xiaolong; Shi, Jingjing; Yu, Si-Yue; Wiita; Paul J.; Ho, Luis C.; Wu, Xue-Bing; An, Tao; Wang, Ran; Subramanian, S; Yesuf, Hassen (IOP Publishing, 2019-12)
    In pursuit of clues to the origin of “ winged ” or X-shaped radio galaxies ( XRGs ) we investigate the parent galaxies of a large sample of 106 XRGs for optical – radio axes alignment, interstellar medium, black ...
  • Yang, Xiaolong; Ji, Jialu; Joshi, Ravi; Yang, Jun; An, Tao; Wang, Ran; Ho, Luis C; Roberts, David H; Saripalli, Lakshmi (IOP Publishing, 2022-07-01)
    X-shaped radio galaxies (XRGs) are those that exhibit two pairs of unaligned radio lobes (main radio lobes and wings). One of the promising models for the peculiar morphology is jet reorientation. To clarify this, we ...
  • Ni, Qingling; Brand, W. N; Chen, Chien-Ting; Luo, Bin; Nyland, Kristina; Yang, Guang; Zou, Fan; Aird, James; Alexander, David M; Bauer, Franz Erik; Lacy, Mark; Lehmer, Bret D; Mallick, Labani; Salvato, Mara; Schneider, Donald P; Tozzi, Paolo; Traulsen, Iris; Vaccari, Mattia; Vignali, Cristian; Vito, Fabio; Xue, Yongquan; Banerji, Manda; Chow, Kate; Comastri, Andrea; Del Moro, Agnese; Gilli, Roberto; Mullaney, James; Paolillo, Maurizio; Schwope, Axel; Shemmer, Ohad; Sun, Mouyuan; Timlin III, John D; Trump, Jonathan R (IOP Publishing, 2021-09)
    We present the X-ray point-source catalogs in two of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields, W-CDF-S (4.6 deg2) and ELAIS-S1 (3.2 deg2), aiming to fill the gap between deep pencil-beam ...
  • Kameswara Rao, N; Ashok, N. M; Kulkarni, P. V (Indian Academy of Sciences, 1980-09)
    Infrared observations obtained six years apart of the R CrB type star XX Cam do not show any infrared excess, unlike all other members of the class. The observed colours match a 7000 K black body energy distribution quite ...
  • Mallik, D. C. V; Mallik, S. G. V (Indian Academy of Sciences, 1985-09)
    Nucleosynthetic yields and production rates of He and heavy elements are derived using recent revisions in O star counts and the stellar models of Maeder (1981). The current production rates and yields are significantly ...
  • Subramaniam, A; Sagar, R (The European Southern Observatory, 1995-05)
    We compare the observed colour-magnitude diagrams (CMD) and the main sequence luminosity functions (LFs) of four Large Magellanic Cloud (LMC) star clusters namely, NGC 1711, NGC 2004, NGC 2164 and NGC 2214 with the synthetic ...

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