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Browsing by Subject "galaxies: active"

Browsing by Subject "galaxies: active"

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  • Accretion disc sizes from continuum reverberation mapping of AGN selected from the ZTF survey 
    Jha, Vivek Kumar; Joshi, Ravi,et.al. (Monthly Notices of the Royal Astronomical Society, 2022-04)
    We present the accretion disc-size estimates for a sample of 19 active galactic nuclei (AGNs) using the optical g-, r-, and i-band light curves obtained from the Zwicky Transient Facility survey. All the AGNs have reliable ...
  • BL Lac object OJ 287: exploring a complete spectrum of issues concerning relativistic jets and accretion 
    Kushwaha, Pankaj (Journal Astrophysical Astronomy, 2022-11)
    BL Lacertae (BL Lac) object OJ 287 is one of the most dynamic blazars across the directly accessible observational windows: spectral, timing, polarization and imaging. Apart from behaviors, considered the characteristics ...
  • A comparative study of the physical properties for a representative sample of Narrow and Broad-line Seyfert galaxies 
    Jha, Vivek Kumar; Chand, Hum; Ojha, Vineet; Omar, Amitesh; Rastogi, Shantanu (Monthly Notices of the Royal Astronomical Society, 2022-03)
    We present a comparative study of the physical properties of a homogeneous sample of 144 Narrow line Seyfert 1 (NLSy1) and 117 Broad-line Seyfert 1 (BLSy1) galaxies. These two samples are in a similar luminosity and ...
  • An empirical relation to estimate host galaxy stellar light from AGN spectra 
    Jalan, Priyanka; Rakshit, Suvendu; Woo, Jong-Jak; Kotilainen, Jari; Stalin, C. S. (Monthly Notices of the Royal Astronomical Society Letters, 2023-05)
    Measurement of black hole mass for low-z (z≤ 0.8) Active Galactic Nuclei (AGNs) is difficult due to the strong contribution from host galaxy stellar light necessitating detailed spectral decomposition to estimate the AGN ...
  • Evidence of jet-induced optical microvariability in radio-loud narrow-line Seyfert 1 galaxies 
    Ojha, Vineet; Jha, Vivek Kumar; Chand, Hum; Singh, Veeresh (Monthly Notices of the Royal Astronomical Society, 2022-08)
    To quantify the role of radio jets for Intra-Night Optical Variability (INOV) in radio-loud narrow-line Seyfert 1 (RLNLSy1) galaxies, we report the first systematic comparative INOV study of 23 RLNLSy1 galaxies, with 15 ...
  • Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and γ -ray brightness levels 
    Raiteri, C. M. , et.al.; Gaur, H.; Gupta, A. C.; Kishore, S.; Wani, K. (Monthly Notices of the Royal Astronomical Society, 2023-12)
    In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and γ -ray bands. We present optical photometric and polarimetric data acquired by the ...
  • Host galaxy properties of quasi-periodically erupting X-ray sources 
    Wevers, T.; Pasham, D. R.; Jalan, P.; Rakshit, S.; Arcodia, R. (Astronomy & Astrophysics, 2022-03)
    Quasi-periodic X-ray eruptions (QPEs) are a recently discovered phenomenon, the nature of which remains unclear. Based on their discovery in active galactic nuclei (AGNs), explanations related to an AGN accretion disk or ...
  • Intra-night optical variability study of a non-jetted narrow-line Seyfert 1 galaxy: SDSS J163401.94+480940.1 
    Ojha, Vineet (Journal of Astrophysics & Astronomy, 2022-05)
    SDSS J163401.94þ480940.1 is a non-jetted radio-loud narrow-line Seyfert 1 (NLSy1) galaxy. Optical monitoring of this object was carried out in two intra-night sessions each 3 h with 3.6-m DOT. Intra-night optical ...
  • Intranight optical variability of blazars and radio-quiet quasars using the ZTF survey 
    Negi, Vibhore; Krishna, Gopal; Joshi, Ravi; Chand, Hum; Wiita, Paul J.; Navaneeth, P. K.; Singh, Ravi S. (Monthly Notices of the Royal Astronomical Society, 2023-07)
    We explore the potential of the ongoing Zwicky Transient Facility (ZTF) survey for studying intranight optical variability (INOV) of active galactic nuclei (AGNs), in particular for picking rare events of large INOV ...
  • Intranight optical variability of low-mass active galactic nuclei: a pointer to blazar-like activity 
    Krishna, Gopal, et.al.; Chand, Krishan (Monthly Notices of the Royal Astronomical Society Letters, 2023-01)
    This study aims to characterize, for the first time, intranight optical variability (INOV) of low-mass active galactic nuclei (LMAGNs) which host a black hole (BH) of mass MBH ∼ 106M , i.e. even less massive than the ...
  • Intranight optical variability of TeV blazars with parsec-scale jets dominated by slow-moving radio knots 
    Negi, Vibhore; Krishna, Gopal; Chand, Hum; Britzen, Silke (Monthly Notices of the Royal Astronomical Society, 2023-09)
    BL Lac objects detected at TeV energies preferentially belong to the subclass called ‘high-frequency-peaked’ BL Lacs (HBLs). Parsec-scale radio jetsin these TeV-HBLs often show dominant,slow-moving radio knotsthat are at ...
  • Intranight variability of ultraviolet emission from powerful blazars 
    Chand, Krishan; Krishna, Gopal; Omar, Amitesh; Chand, Hum; Mishra, Sapna; Bisht, P. S.; Britzen, S. (Monthly Notices of the Royal Astronomical Society Letters, 2022-03)
    We report the first study to characterize intranight variability of the blazar class from the perspective of (rest-frame) ultraviolet (UV) emission. For this, we carried out intranight optical monitoring of 14 flat-spectrum ...
  • Investigating the origin of optical flares from the TeV blazar S4 0954+65 
    Pandey, Ashwani; Bachev, Rumen; Czerny, Bo˙zena; Wiita, Paul J.; Gupta, Alok C.; Strigachev, Anton; Popowicz, Adam (Astronomy & astrophysics, 2023-11)
    Aims. We aim to investigate the extreme variability properties of the TeV blazar S4 0954+65 using optical photometric and polarisation observations carried out between 2017 and 2023 using three ground-based telescopes. Methods. ...
  • LOFAR discovery of rare large FR I jets in the low-luminosity radio galaxy NGC 5322 
    Omar, Amitesh (Monthly Notices of the Royal Astronomical Society Letters, 2022-11)
    The discovery of faint Fanaroff–Riley type I (FR I) radio jets in the elliptical galaxy NGC 5322 is reported here using the 144-MHz image from Data Release 2 of the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS). ...
  • Multi-wavelength characterization of Fermi blazars of uncertain type 
    Paliya, Vaidehi S. (Journal of Astrphysics and Astronomy, 2022-06)
    One of the major challenges in the research of jetted active galactic nuclei (AGN) is the completeness of the source catalogs released using the c-ray data taken from the Fermi-large area telescope (LAT). There are about ...
  • Multiband cross-correlated radio variability of the blazar 3C 279 
    Mohana A, Krishna; Gupta, Alok C.; Marscher, Alan P.; Sotnikova, Yulia V.; Jorstad, S. G.; Wiita, Paul J.; Cui, Lang; Aller, Margo F.; Aller, Hugh D.; Kovalev, Yu. A.; Kovalev, Y. Y.; Liu, Xiang; Mufakharov, T. V.; Popkov, A. V.; Mingaliev, M. G.; Erkenov, A. K.; Nizhelsky, N. A.; Tsybulev, P. G.; Tsybulev, P. G.; Zhao, Wei; Weaver, Z. R.; Morozova, D. A. (Monthly Notices of the Royal Astronomical Society, 2024-01)
    We present the results of our study of cross-correlations between long-term multiband observations of the radio variability of the blazar 3C 279. More than a decade (2008–2022) of radio data were collected at seven different ...
  • Multiband optical variability of the TeV blazar PG 1553 + 113 in 2019 
    Dhiman, Vinit; Gupta, Alok C. ,et.al.; Gaur, Haritma (Monthly Notices of the Royal Astronomical Society, 2023-02)
    We report the flux and spectral variability of PG 1553 + 113 on intra-night (IDV) to short-term time-scales using BVRI data collected over 91 nights from 28 February to 8 November 2019 employing 10 optical telescopes: ...
  • Multiband optical variability on diverse time-scales of the TeV blazar TXS 0506 + 056, the first cosmic neutrino source 
    Dhiman, Vinit; Gupta, Alok C.; Bachev, Rumen; Wiita, Paul J.; Cellone, Sergio A.; Strigachev, A.; Gaur, Haritma; Darriba, A.; Bisen, D. P.; Locatelli, G.; Mammana, L. A.; Semkov, E. (Monthly Notices of the Royal Astronomical Society, 2024-01)
    We report the first extensive optical flux and spectral variability study of the TeV blazar TXS 0506 + 056 on intranight to long-term time-scales using BVRI data collected over 220 nights between 2017 January 21 to 2022 ...
  • On the origin of core radio emissions from black hole sources in the realm of relativistic shocked accretion flow 
    Das, Santabrata ,et.al.; Rakshit, Suvendu (Monthly Notices of the Royal Astronomical Society, 2022-08)
    We study the relativistic, inviscid, advective accretion flow around the black holes and investigate a key feature of the accretion flow, namely the shock waves. We observe that the shock-induced accretion solutions are ...
  • The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics 
    Raiteri, C. M. , et.al.; Dhiman, V.; Gaur, H.; Gupta, A. C.; Kushwaha, P.; Tripathi, T. (Monthly Notices of the Royal Astronomical Society, 2023-06)
    In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical data in the BVRI bands acquired at 36 ...

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