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Browsing IIAP Publications by Subject "Quasars: general"

Browsing IIAP Publications by Subject "Quasars: general"

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  • Appearance versus disappearance of broad absorption line troughs in quasars 
    Mishra, Sapna; Vivek, M; Chand, Hum; Joshi, Ravi (Oxford University Press on behalf of the Royal Astronomical Society, 2021-07)
    We present a new set of 84 broad absorption line (BAL) quasars (1.7 < zem < 4.4) exhibiting an appearance of C IV BAL troughs over 0.3–4.8 rest-frame years by comparing the Sloan Digital Sky Survey Data Release (SDSSDR)-7, ...
  • Authenticating the presence of a relativistic massive black hole binary in OJ 287 using Its general relativity centenary flare: improved orbital parameters 
    Dey, L; Valtonen, M. J; Gopakumar, A; Zola, S; Hudec, R; Pihajoki, P; Ciprini, S; Matsumoto, K; Sadakane, K; Kidger, M; Nilsson, K; Mikkola, S; Sillanpaa, A; Takalo, L. O; Lehto, H. J; Berdyugin, A; Piirola, V; Jermak, H; Baliyan, K. S; Pursimo, T; Caton, D. B; Alicavus, F; Baransky, A; Blay, P; Boumis, P; Boyd, D; Campas Torrent, M; Campos, F; Carrillo Gomez, J; Chandra, S; Chavushyan, V; Dalessio, J; Debski, B; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Gafton, E; Ganesh, S; Garcia, F; Gazeas, K; Godunova, V; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Harmanen, J; Hurst, G; Janik, J; Jelinek, M; Joshi, A; Kagitani, M; Karjalainen, R; Kaur, N; Keel, W. C; Kouprianov, V. V; Kundera, T; Kurowski, S; Kvammen, A; LaCluyze, A. P; Lee, B. C; Liakos, A; Lindfors, E; Lozano de Haro, J; Mugrauer, M; Naves Nogues, R; Neely, A. W; Nelson, R. H; Ogloza, W; Okano, S; Pajdosz-Smierciak, U; Pandey, J. C; Perri, M; Poyner, G; Provencal, J; Raj, A; and 27 co-authors (IOP Publishing, 2018-10-10)
    Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the ...
  • Does black hole spin play a key role in the FSRQ/BL Lac dichotomy? 
    Bhattacharya, D; Sreekumar, P; Mukhopadhyay, B; Tomar, I (IOP Publishing, 2016-04)
    Blazars are characterized by large intensity and spectral v ariations across the electromagnetic spectrum It is believed that jets emerging from them are almo st aligned with the line-of-sight. The major- ity of ...
  • Evidence of underdeveloped torus and broad-line region of weak emission line quasars based on their spectral energy distribution 
    Kumar, Ritish; Chand, Hum; Joshi, Ravi (Oxford University Press on behalf of Royal Astronomical Society, 2023-03)
    To unravel the dominant cause of the weak emission line in a subset of optically selected radio-quiet 'weak emission line quasars' (WLQs), we have investigated the possibility of an underdeveloped broad line region (BLR). ...
  • Frequency-dependent core shifts and parameter estimation for the blazar 3C 454.3 
    Mohan, Prashanth; Agarwal, A; Mangalam, A; Gupta, A. C; Wiita, P. J; Volvach, A. E; Aller, M. F; Aller, H. D; Gu, M. F; Lahteenmaki, A; Tornikoski, M; Volvach, L. N (Oxford University Press on behalf of the Royal Astronomical Society, 2015-09-11)
    We study the core shift effect in the parsec-scale jet of the blazar 3C 454.3 using the 4.8– 36.8 GHz radio light curves obtained from three decades of continuous monitoring. From a piecewise Gaussian fit to each flare, ...
  • From nearby low luminosity AGN to High Redshift Radio Galaxies: science interests with square kilometre array 
    Kharb, P; Lal, D. V; Singh, V; Bagchi, J; Ishwara-Chandra, C. H; Hota, A; Konar, C; Wadadekar, Yogesh; Shastri, P; Mousumi Das; Baliyan, K; Nath, B. B; M. Pandey-Pommier (Springer, 2016-12)
    We present detailed science cases that a large fraction of the Indian AGN community is interested in pursuing with the upcoming Square Kilometre Array (SKA). These interests range from understanding low luminosity active ...
  • Gamma-Ray Blazars within the first 2 billion years 
    Ackermann, M; Ajello, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Becerra Gonzalez, J; Bellazzini, R; Bissaldi, E; Blandford, R. D; Bloom, E. D; Bonino, R; Bottacini, E; Bregeon, J; Bruel, P; Buehler, R; Buson, S; Cameron, R. A; Caragiulo, M; Caraveo, P. A; Cavazzut, E; Cecchi, C; Cheung, C. C; Chiang, J; Chiaro, G; Ciprini, S; Conrad, J; Costantin, D; Costanza, F; Cutini, S; D'Ammando, F; de Palma, F; Desiante, R; Digel, S. W; Di Lalla, N; Di Mauro, M; Di Venere, L; Domi­nguez, A; Drell, P. S; Favuzzi, C; Fegan, S. J; Ferrara, E. C; Finke, J; Focke, W. B; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Giordano, F; Giroletti, M; Green, D; Grenier, I. A; Guillemo, L; Guiriec, S; Hartmann, D. H; Hays, E; Marcotulli, L; Horan, D; Jogler, T; Johannesson, G; Johnson, A. S; Kuss, M; Mura, G. La; Larsson, S; Latronico, L; Li, J; Longo, F; Mazziotta, M. N; Loparco, F; Lovellette, M. N; Lubrano, P; Magill, J. D; Maldera, S; Manfreda, A; Michelson, P. F; Mirabal, N; Mitthumsiri, W; Mizuno, T; Monzani, M. E|; Morselli, A; Moskalenko, I. V; Negro, M; Rando, R; Nuss, E; Ohsugi, T; Ojha, R; Omodei, N; Orienti, M; Orlando, E; Ormes, J. F; Paliya, V. S; Paneque, D; Perkins, J. S; Rani, B; Persic, M; Pesce-Rollins, M; Piron, F; Porter, T. A; Principe, G; Raino, S; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Roman, R. W; Sgro, C; Simone, D; Siskind, E. J; Spada, F; Spandre, G; Spinelli, P; Stalin, C. S; 12 others (IOP Publishing, 2017-03-01)
    The detection of high-redshift ($z\,\gt 3$) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and ...
  • Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxies in the Sloan Digital Sky Survey 
    Paliya, Vaidehi S; Ajello, M; Rakshit, S; Amit Kumar; Stalin, C. S; Kaur, A; Hartmann, D (IOP Publishing, 2018-01)
    The detection of signi fi cant γ -ray emission from radio-loud narrow-line Seyfert 1 ( NLSy1s ) galaxies enables us to study jets in environments different than those in blazars. However, due to the small number ...
  • H0 from ten well-measured time delay lenses 
    Rathna Kumar, S; Stalin, C. S; Prabhu, T. P (EDP Sciences, 2015-08)
    In this work, we present a homogeneous curve-shifting analysis using the difference-smoothing technique of the publicly available light curves of 24 gravitationally lensed quasars, for which time delays have been reported ...
  • Intra-night optical variability monitoring of c-ray emitting blazars 
    Pandian, K Subbu Ulaganatha; Natarajan, A; Stalin, C. S; Pandey, Ashwani; Muneer, S; Natarajan, B (Indian Academy of Sciences, 2022-12)
    We present the results obtained from our campaign to characterize the intra-night optical variability properties of blazars detected by the Fermi large area telescope. This involves R-band monitoring observations of a ...
  • Intra-night Optical Variability Monitoring of Fermi Blazars: First Results from 1.3 m J. C. Bhattacharya Telescope 
    Paliya, Vaidehi S; Stalin, C. S; Ajello, M; Kaur, A (IOP Publishing, 2017-08)
    We report the first results obtained from our campaign to characterize the intra-night-optical variability (INOV) properties of Fermi detected blazars, using the observations from the recently commissioned 1.3 m J. ...
  • Intra-night optical variability of core dominated radio quasars: the role of optical polarization 
    Goyal, A; Gopal-Krishna; Wiita, P. J; Anupama, G. C; Sahu, D. K; Sagar, R; Joshi, S (EDP Sciences, 2012-08)
    Context. Rapid variations in optical flux are seen in many quasars and all blazars. The amount of variability in different classes of active galactic nuclei has been studied extensively but many questions remain unanswered. ...
  • Intra-night optical variability of misaligned active galaxies 
    Bhattacharya, Debbijoy; Gulati, S; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2019-03)
    The majority of the γ-ray sources detected by the Fermi Gamma-ray Space Telescope belong to the blazar class of active galactic nuclei (AGNs). In addition to blazars, a minority of non-blazar AGNs is also found to be γ-ray ...
  • Intra-night optical variability of misaligned active galaxies 
    Bhattacharya, Debbijoy; Gulati, S; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2019-03)
    The majority of the γ-ray sources detected by the Fermi Gamma-ray Space Telescope belong to the blazar class of active galactic nuclei (AGNs). In addition to blazars, a minority of non-blazar AGNs is also found to be γ-ray ...
  • Intranight optical variability of blazars and radio-quiet quasars using the ZTF survey 
    Negi, Vibhore; Gopal-Krishna; Joshi, Ravi; Chand, Hum; Wiita, Paul J; Navaneeth, P. K; Singh, Ravi S (Oxford University Press on behalf of 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 γ -ray-loud narrow-line Seyfert 1 galaxies 
    Paliya, Vaidehi S; Stalin, C. S; Kumar, Brijesh; Kumar, Brajesh; Bhatt, V. K; Pandey, S. B; Yadav, K. S (Oxford University Press on behalf of the Royal Astronomical Society, 2013-01-21)
    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope has detected γ-ray emission in about half a dozen narrow-line Seyfert 1 (NLSy1) galaxies. This indicates the presence of relativistic jets in these ...
  • Multi-epoch intranight optical monitoring of eight radio-quiet BL Lac candidates 
    Kumar, P; Gopal-Krishna; Stalin, C. S; Chand, H; Srianand, R; Petitjean, P (Oxford University Press on behalf of the Royal Astronomical Society, 2017-10)
    For a new sample of eight weak-line quasars (WLQs) we report a sensitive search in 20 intranight monitoring sessions, for blazar-like optical flux variations on hour-like and longer time-scale (day/month/year-like). The ...
  • A multiwavelength study of three hybrid blazars 
    Stanley, E. C; Kharb, P; Lister, M. L; Marshall, H. L; O'Dea, C; Baum, S (IOP Publishing, 2015-07-01)
    We present multiwavelength imaging observations of PKS 1045−188, 8C 1849+670, and PKS 2216−038, three radio-loud active galactic nuclei from the MOJAVE-Chandra Sample that straddle the Fanaroff-Riley (FR) boundary between ...
  • NuSTAR, Swift, and GROND observations of the flaring MeV blazar PMN J0641-0320 
    Ajello, M; Ghisellini, G; Paliya, Vaidehi S; Kocevski, D; Tagliaferri, G; Madejski, G; Rau, A; Schady, P; Greiner, J; Massaro, F; Balokovic, M; Buhler, R; Giomi, M; Marcotulli, L; D'Ammando, F; Stern, D; Boggs, S. E; Christensen, F. E; Craig, W. W; Hailey, C. J; Harrison, F. A; Zhang, W. W (IOP Publishing, 2016-07-20)
    MeV blazars are a sub-population of the blazar family, exhibiting larger-than-average jet powers, accretion luminosities, and black hole masses. Because of their extremely hard X-ray continua, these objects are best studied ...
  • Optical flux and colour variability of blazars in the ZTF survey 
    Negi, Vibhore; Joshi, Ravi; Chand, Krishan; Chand, Hum; Wiita, Paul; Ho, Luis C; Singh, Ravi S (Oxford University Press on behalf of Royal Astronomical Society, 2022-02)
    We investigate the temporal and colour variability of 897 blazars, comprising 455 BL Lacertae objects (BL Lacs) and 442 Flat Spectrum Radio Quasars (FSRQs), selected from the Roma-BZCAT catalogue, using the multiband light ...

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