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Browsing by Subject "galaxies: active"

Browsing by Subject "galaxies: active"

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  • Are narrow-line seyfert 1 galaxies powered by low-mass black holes? 
    Viswanath, G; Stalin, C. S; Rakshit, S; Kurian, K. S; Ujjwal, K.; Gudennavar, S. B; Kartha, S. S (IOP Publishing, 2020-03)
    Are Narrow-line Seyfert 1 Galaxies Powered by Low-mass Black Holes? Gayathri Viswanath 1 , C. S. Stalin 2 , Suvendu Rakshit 3 , Kshama S. Kurian 2 , K. Ujjwal 1 , Shivappa B. Gudennavar 1 , and Sreeja S. ...
  • Changing look AGN Mrk 590: broad-line region and black hole mass from photometric reverberation mapping 
    Amit Kumar Mandal; Schramm, Malte; Rakshit, Suvendu; Stalin, C. S; Vijarnwannaluk, Bovornpratch; Rujopakarn, Wiphu; Poshyachinda, Saran; Kouprianov, Vladimir V; Haislip, Joshua B; Reichar, Daniel E; Sagar, R; Mathew, Blesson (Oxford University Press on behalf of Royal Astronomical Society, 2021-12)
    We present the results of photometric reverberation mapping observations on the changing look active galactic nucleus Mrk 590 at z = 0.026. The observations were carried out from 2018 July to December using broad-band B-, ...
  • Dust reverberation mapping of Z229–15 
    Mandal, A. K; Rakshit, S; Stalin, C. S; Wylezalek, D; Patig, M. K; Sagar, R; Mathew, B; Muneer, S; Pal, I (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    We report results of the dust reverberation mapping (DRM) on the Seyfert 1 galaxy Z229–15 at z = 0.0273. Quasi-simultaneous photometric observations for a total of 48 epochs were acquired during the period 2017 July to ...
  • Long term γ-ray variability of blazars 
    Rajput, Bhoomika; Stalin, C. S; Rakshit, S (EDP Sciences, 2020-02)
    We used the data from the Fermi Gamma-ray Space Telescope to characterise the γ-ray flux variability of blazars on month-like time scales. Our sample consists of 1120 blazars of which 481 are flat spectrum radio quasars ...
  • Mid-infrared variability of γ-ray emitting blazars 
    Anjum, A; Stalin, C. S; Rakshit, S; Gudennavar, S. B; Durgapal, A (Oxford University Press on behalf of the Royal Astronomical Society, 2020-05)
    Using data from the Wide-field Infrared Survey Explorer, we studied the mid-infrared (mid-IR) 3.4 μm (W1-band) and 4.6 μm (W2-band) flux variability of γ-ray emitting blazars. Our sample consists of 460 flat spectrum radio ...
  • A model for relativistic disk emission, flow and variability 
    Mohan, Prashanth; Mangalam, A (Astronomical Society of India, 2015-04)
    Orbiting features near a black hole can cause variability in optical/UV and X-ray bands with quasi-periodic signatures. The variable flux is derived in Kerr geometry including the following relativistic effects: light ...
  • Multi-band behaviour of the TeV blazar PG 1553+113 in optical range on diverse timescales 
    Agarwal, A; Mihov, B; Andruchow, I; Cellone, S. A; Anupama, G. C; Agrawal, V; Zola, S; Slavcheva, L; Slavcheva-Mihova, L; Ozdonmez, A; Ege, Ergun; Raj, A; Mammana, L; Zibecchi, L; Fernandez-Lajus, E (EDP Sciences, 2021-01)
    Context. The TeV BL Lac object PG 1553+113 is one of the primary candidates for a binary supermassive black hole system. Aims. We study the flux and spectral variability of PG 1553+113 on intra-night to long-term ...
  • Multiband optical variability of 3C 279 on diverse time scales 
    Aditi Agarwal; Cellone, Sergio A; Andruchow, I; Mammana, Luis; Singh, Mridweeka; Anupama, G. C; Mihov, B; Raj, A; eva-Mihova, L; Ozdonmez, Aykut; Ege, Ergun (Oxford University Press on behalf of the Royal Astronomical Society, 2019-09)
    We have monitored the flat spectrum radio quasar, 3C 279, in the optical B, V, R, and I passbands from 2018 February to 2018 July for 24 nights, with a total of 716 frames, to study flux, colour, and spectral variability ...
  • A multifrequency study of the large radio galaxies 3C46 and 3C452 
    Nandi, S; Pirya, A; Pal, S; Konar, C; Saikia, D. J; Singh, M (Wiley-Blackwell, 2010-05)
    We present low-frequency observations starting from ∼150 MHz with the Giant Metrewave Radio Telescope, and high-frequency observations with the Very Large Array of two large radio galaxies 3C46 and 3C452. These observations ...
  • Multiwavelength study of different flaring and low-activity states of blazar 4C+21.35 
    Bhattacharya, D; Krishna Mohana, A; Bhattacharyya, S; Bhatt, N; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    Blazars, a class of active galactic nuclei, emit over the entire accessible electromagnetic spectrum and modelling of their broad-band spectral energy distribution (SED) is the key to constrain the underlying emission ...
  • A multiwavelength study of the dual nuclei in Mrk 212 
    Rubinur, K; Kharb, P; Das, M; Rahna, P. T; Honey, M; Paswan, A; Vaddi, S; Murthy, J (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    We present radio observations of the galaxy merger remnant Mrk 212 with the Karl G. Jansky Very Large Array (VLA) and the upgraded Giant Meter Radio Telescope (uGMRT). Mrk 212 has two previously known radio sources associated ...
  • Narrow-line Seyfert 1 galaxies in Sloan Digital Sky Survey: a new optical spectroscopic catalogue 
    Paliya, Vaidehi S; Stalin, C. S; Dominguez, Alberto; Saikia, D. J (Oxford University Press on behalf of Royal Astronomical Society, 2024-01)
    Narrow-line Seyfert 1 (NLSy1) galaxies are an enigmatic class of active galactic nuclei (AGN) that exhibit peculiar multiwavelength properties across the electromagnetic spectrum. For example, these sources have allowed ...
  • Optical and GeV flux variations in Fermi blazars 
    Stalin, C. S (Astronomical Society of India, 2015-04)
    A large fraction of γ-ray emitting blazars show correlated flux variations in the optical and γ-ray bands with little or no time lag. However, in a minority of them, uncorrelated optical and γ-ray flux variations are seen. ...
  • Properties of radio-loud quasars in the Sloan Digital Sky Survey 
    Gaur, H; Gu, M; Ramya, S; Guo, H (EDP Sciences, 2019-11)
    We present a study of a sample of 223 radio-loud quasars (up to redshift < 0.3) in order to investigate their spectral properties. Twenty-six of these radio-loud quasars are identified as flat-spectrum radio quasars (FSRQs), ...
  • Spectral ageing analysis and dynamical analysis of the double-double radio galaxy J1548–3216 
    Machalski, J; Jamrozy, M; Konar, C (EDP Sciences, 2010-02)
    Context. Determining ages of the outer and the inner lobes of so-called double-double radio galaxies (DDRGs) is crucial for understanding the active cycles of galactic nuclei, the phases of interruption of the jet flow, ...
  • Stochastic modeling of multiwavelength variability of the classical BL Lac Object OJ 287 on timescales ranging from decades to hours 
    Goyal, A; Stawarz, L; Zola, S; Marchenko, V; Soida, M; Nilsson, K; Ciprini, S; Baran, A; Ostrowski, M; Wiita, P. J; Gopal-Krishna; iemiginowska, A; Sobolewska, M; Jorstad, S; Marscher, A; Aller, M. F; Aller, H. D; Hovatta, T; Caton, D. B; Reichart, D; Matsumoto, K; Sadakane, K; Gazeas, K; Kidger, M; Piirola, V; Jermak, H; Alicavus, F; Baliyan, K. S; Baransky, A; Berdyugin, A; Blay, P; Boumis, P; Boyd, D; Bufan, Y; Campas Torrent, M; Campos, F; Carrillo Gomez, J; Dalessio, J; Debski, B; Dimitrov, D; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Gafton, E; Garcia, F; Godunova, V; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Haque, S; Harmanen, J; Hudec, R; Hurst, G; Ivarsen, K. M; Joshi, A; Kagitani, M; Karaman, N; Karjalainen, R; Kaur, N; Koziel-Wierzbowska, D; Kuligowska, E; Kundera, T; Kurowski, S; Kvammen, A; LaCluyze, A. P; Lee, B. C; Liakos, A; Lozano de Haro, J; Moore, J. P; Mugrauer, M; Naves Nogues, R; Neely, A. W; Ogloza, W; Okano, S; Pajdosz, U; Pandey, J. C; Perri, M; Poyner, G; Provencal, J; Pursimo, T; Raj, A; and 29 co-authors (IOP Publishing, 2018-08-20)
    We present the results of our power spectral density analysis for the BL Lac object OJ 287, utilizing the Fermi-LAT survey at high-energy γ-rays, Swift-XRT in X-rays, several ground-based telescopes and the Kepler satellite ...
  • Unravelling the nuclear dust morphology of NGC 1365: a two-phase polar–RAT model for the ultraviolet to infrared spectral energy distribution 
    Swain, Subhashree; Shalima, P; Latha, K. V. P (Oxford University Press on behalf of Royal Astronomical Society, 2024-01)
    We present a 3D radiative transfer model for the spectral energy distribution (SED) of NGC 1365, which is a ‘changing look’ Seyfert 1.8 type active galactic nucleus (AGN). The SED from the ultraviolet (UV) to the infrared ...

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