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Browsing by Author "Gopal-Krishna"

Browsing by Author "Gopal-Krishna"

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  • A physically-motivated perspective of Fanaroff–Riley classification of radio galaxies 
    Gopal-Krishna; Wiita, Paul J; Joshi, Ravi; Patra, Dusmanta (Indian Academy of Sciences, 2023-06)
    A small subset of extragalactic double radio sources, termed HYbrid MOrpholgy Radio Sources (HYMORS), is distinguished by a very unusual, hybrid morphology in terms of Fanaroff–Riley (FR) classification. In HYMORS, one ...
  • Polarimetric and spectroscopic study of radio quiet weak emission line quasars 
    Kumar, P; Chand, H; Srianand, R; Stalin, C. S; Petitjean, P; Gopal-Krishna (Oxford University Press on behalf of the Royal Astronomical Society, 2018-10)
    A small subset of optically selected radio-quiet quasars showing weak or no emission lines may turn out to be the elusive radio-quiet BL Lac objects, or simply be radio-quiet QSOs with a still-forming/shielded broad line ...
  • Prolonged intranight optical quiescence of the classical BL Lac object PKS 0735+178 
    Goyal, A; Gopal-Krishna; Anupama, G. C; Sahu, D. K; Sagar, R; Britzen, S; Karazous, M; Aller, M. F; Aller, H. D (Astronomical Society of the Pacific, 2009-09)
    We report our extensive intranight optical monitoring of the well known low-energy peaked (LBL) BL Lac object PKS 0735+178. This long-term follow-up consists of R-band monitoring for a minimum duration of ˜ 4 hours, on 17 ...
  • The Radio Source Projected Near the Absorption-Line QSO PHL 5200 
    Gopal-Krishna (Astronomical Society of India, 1978-12)
    Some recently discovered properties of the radio source 4C - 05.93 are summarised. Their relevance to the observed absorption-line spectrum of the QSO PHL 5200, which is located onl 1 arcmin away from the radio source, is ...
  • Rapid optical variability of TeV blazars 
    Gopal-Krishna; Goyal, A; Joshi, S; Karthick, C; Sagar, R; Wiita, P. J; Anupama, G. C; Sahu, D. K (Wiley-Blackwell, 2011-09)
    In this first systematic attempt to characterize the intranight optical variability (INOV) of TeV-detected blazars, we have monitored a well-defined set of nine TeV blazars on total 26 nights during 2004–10. In this R- or ...
  • A search for intra-night optical variability in radio-quiet QSOs 
    Gopal-Krishna; Sagar, R; Witta, P. J (Royal Astronomical Society, 1993-06-15)
    We report results from a new program, using the 2.34-m Vainu Bappu Telescope, to search for intra-night optical variability in five QSOs which are radio-quiet but optically bright and luminous. Our limited data show mild ...
  • Spectral index variation across X-shaped radio galaxies 
    Patra, Dusmanta; Joshi, Ravi; Gopal-Krishna (Oxford University Press on behalf of Royal Astronomical Society, 2023-09)
    The formation mechanism of the enigmatic subclass of radio galaxies, called ‘X-shaped radio galaxies’ (XRGs), or ‘winged’ radio galaxies, which account for ∼10 per cent of the radio galaxy population, can be effectively ...
  • Stellar Disruption by Supermassive Black Holes and the Quasar Radio Loudness Dichotomy 
    Gopal-Krishna; Mangalam, A; Wiita, P. J (The American Astronomical Society, 2008-06-10)
    The origin of the dichotomy of radio loudness among quasars can be explained using recent findings that the mass of the central supermassive black hole (SMBH) in extended radio-loud quasars is systematically a few times ...
  • 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 ...
  • Testing the mechanisms for optical micro-variability of powerful active galactic nuclei 
    Gopal-Krishna; Sagar, R; Wiita, P. J (Astronomical Society of India, 1993)
    We present the first results of a new type of observational program being carried out using the 2.34m Vainu Bappu Telescope at Kavalur. This program involves intra-night optical monitoring of radio quiet but optically ...
  • The twin radio galaxy TRG J104454+354055 
    Gopal-Krishna; Joshi, Ravi; Patra, Dusmanta; Yang, Xiaolong; Ho, Luis C; Wiita, Paul J; Omar, Amitesh (Oxford University Press on behalf of Royal Astronomical Society, 2022-07)
    We report observations of a bright dumb-bell system of galaxies (z = 0.162) with the upgraded Giant Metrewave Radio Telescope (uGMRT), which show that each member of this gravitationally bound pair of galaxies hosts bipolar ...
  • Unusual optical quiescence of the classical BL Lac object PKS 0735+178 on intranight time scale 
    Goyal, A; Gopal-Krishna; Anupama, G. C; Sahu, D. K; Sagar, R; Britzen, S; Karouzos, M; Aller, M. F; Aller, H. D (Wiley Blackwell, 2009-07)
    We present the result of our extensive intranight optical monitoring of the well known low-energy peaked BL Lac (LBL) object PKS 0735+178. This long-term follow-up consists of $R$-band monitoring for a minimum duration of ...

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