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Browsing by Subject "Galaxies: Active"

Browsing by Subject "Galaxies: Active"

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  • Active Galactic Nuclei and Galaxy Formation 
    Chokshi, A (The American Astronomical Society, 1997-12)
    It is proposed that early jet-induced activity around active galactic nuclei (AGNs) is responsible for triggering large-scale star formation in protogalaxies and results in the formation of giant ellipticals and spheroids ...
  • Active galaxies and their importance: results from imaging them in the UV 
    Shastri, P (Astronomical Society of India, 2007-06)
    The current phenomenology of active galaxies is briefly outlined. Their significance in the larger context of galaxy formation and evolution is de- scribed. Recent ultraviolet imaging results are then summarized in the ...
  • Active nucleus in a post-starburst galaxy: KUG 1259+280 
    Dewangan, G. C; Singh, K. P; Mayya, Y. D; Anupama, G. C (The Royal Astronomical Society, 2000-10)
    We report the discovery of an active nucleus in a post-starburst galaxy, KUG 1259+280, based on its X-ray and optical characteristics. The X-ray source in KUG 1259+280 was detected during a search for ultrasoft sources in ...
  • Further evidence for intra-night optical variability of radio-quiet quasars 
    Goyal, Arti; Gopal-Krishna; Sagar, R; Anupama, G. C; Sahu, D. K (Astronomical Society of India, 2007-06)
    Although well established for BL Lac objects and radio-loud quasars, the occurrence of intra-night optical variability (INOV) in radio-quiet quasars is still debated, primarily since only a handful of INOV events with good ...
  • Intranight optical variability in optically selected QSOs 
    Gopal-Krishna; Sagar, R; Wiita, J. Paul (Blackwell Publishing, 1995-06)
    We report results from a continuing programme to search for intranight optical variability in one radio-moderate and six radio-quiet (but all optically bright and luminous) quasi-stellar objects, using the 2.34-m Vainu ...
  • O VI Asymmetry and an Accelerated Outflow in an Obscured Seyfert: FUSE and HST STIS Spectroscopy of Mrk 533 
    Shastri, P; Murthy, J; Whittle, Mark; Wills, B. J (The American Astronomical Society, 2006-07-20)
    We present far-ultraviolet spectra of the Seyfert 2 galaxy Mrk 533 obtained with FUSE. These spectra show narrow asymmetrical O VI λλ1032,1038 emission lines with stronger wings shortward of the peak wavelength, but the ...
  • Obscured and powerful AGN and starburst activities at z ~ 3.5 
    Polletta, M; Omont, A; Berta, S; Bergeron, J; Stalin, C. S; Petitjean, P; Giorgetti, M; Trinchieri, G; Srianand, R; McCracken, H. J; Pei, Y; Dannerbauer, H (EDP Sciences, 2008-12)
    Aims. Short phases of coeval powerful starburst and AGN activity during the lifetimes of the most massive galaxies are predicted by various models of galaxy formation and evolution. In spite of their recurrence and high ...
  • On the injection spectrum of relativistic electrons in high-redshift radio galaxies 
    Gopal-Krishna; Mhaskey, Mukul; Mangalam, A (IOP Publishing, 2012-01-01)
    We point out that the remarkable linearity of the ultra-steep radio spectra of high redshift radio galaxies re ects a previously reported general trend for powerful radio galaxies, according to which the spectral curvature ...
  • Optical and radio variability of the BL Lacertae object AO 0235+16: A possible 5-6 year periodicity 
    Raiteri, C. M; Villata, M; Aller, H. D; Aller, M. F; Heidt, J; Kurtanidze, O. M; Lanteri, L; Maesano, M; Massaro, E; Montagni, F; Nesci, R.; Nilsson, K; Nikolashvili, M. G; Nurmi, P; Ostorero, L; Pursimo, T; Rekola, R; Sillanpää, A; Takalo, L. O; Teräsranta, H; Tosti, G; Balonek, T. J; Feldt, M; Heines, A; Heisler, C; Hu, J.; Kidger, M; Mattox, J. R; McGrath, E. J; Pati, A. K; Robb, R; Sadun, A. C; Shastri, P; Wagner, S. J; Wei, J; Wu, X (E D P Sciences, 2001-10)
    The BL Lacertae object AO 0235+16 is well known for its extreme optical and radio variability. New optical and radio data have been collected in the last four years by a wide international collaboration, which confirm the ...
  • Optical Variability of BL Lacertae during the Major Outburst of 1997 
    Ghosh, K. K; Ramsey, B. D; Sadun, A. C; Soundararajaperumal, S; Wang, J (The American Astronomical Society, 2000-07)
    We have undertaken an investigation of recent flux variability in BL Lac. We present optical observations taken over 22 nights documenting major as well as minor outbursts. This has been combined, for purposes of multifrequency ...
  • Optical Variability of Blazars 
    Ghosh, K. K; Ramsey, B. D; Sadun, A. C; Soundararajaperumal, S (The American Astronomical Society, 2000-03)
    In this paper we show the results of our monitoring the flux variability of 15 blazars, within the redshift range of 0.07-2.06, all with a visual magnitude range between 14 and 20 mag. Because blazars have displayed ...
  • Pc-scale study of radio galaxies and BL Lacs 
    Kharb, P; Shastri, P; Gabuzda, D. C (Elsevier, 2003-10)
    We study two aspects of the differences between Active Galactic Nuclei (AGN) of the two Fanaroff-Riley types in order to investigate the causes of the F-R divide. We: (a) contrast the properties of the optical cores in ...
  • Simultaneous MITSuME g'RCIC monitoring of S5 0716+714 
    Stalin, C. S; Kawabata, K. S; Uemura, M; Yoshida, M; Kawai, N; Yanagisawa, K; Shimizu, Y; Kuroda, D; Nagayama, S; Toda, H (Blackwell Publishing, 2009-11)
    We present the results of our intra-night optical flux monitoring observations of S5 0716+714 done simultaneously in g',RC and IC filters. The observations were done using the Multicolor Imaging Telescopes for Survey and ...
  • Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. X. Variability of Fairall 9 from Optical Data 
    Santos-Lleo, M; Chatzichristou, E; de Oliveira, C. M; Winge, C; Alloin, D; Peterson, B. M; Rodriguez-Pascual, P. M; Stirpe, G. M; Beers, T; Bragaglia, A; Claeskens, J. F; Federspiel, M; Giannuzzo, E; Gregorio-Hetem, J; Mathys, G; Salamanca, I; Stein, P; Stenholm, B; Wilhelm, R; Zanin, C; Albrecht, P; Calderon, J; Caretta, C. A; Carranza, G; da Costa, R. D. D; Diaz, R; Dietrich, M; Dottori, H; Elizalde, F; Goldes, G; Ghosh, K. K; Maia, M. A. G; Paolantonio, S; de Oliveira Filho, R. I; Rodriguez-Ardila, A; Schmitt, H. R; Soundararajaperumal, S; de Souza, R. E; Willmer, C. N. A; Zheng, W (American Astronomical Society, 1997-10)
    The results of an optical monitoring campaign on the active nucleus in the luminous Seyfert 1 galaxy Fairall 9 are presented. This campaign was undertaken in parallel with ultraviolet spectroscopic monitoring with the IUE ...
  • Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XII. Ground-based Monitoring of 3C 390.3 
    Dietrich, M; Peterson, B. M; Albrecht, P; Altmann, M; Barth, A. J; Bennie, P. J; Bertram, R.; Bochkarev, N. G; Bock, H; Braun, J. M; Burenkov, A; Collier, S; Fang, L. Z; Francis, O. P; Filippenko, A. V; Foltz, C. B; Gaessler, W; Gaskell, C. M; Geffert, M; Ghosh, K. K; Hilditch, R. W; Honeycutt, R. K; Horne, K; Huchra, J. P; Kaspi, S; Kuemmel, M; Leighly, K. M; Leonard, D. C; Malkov, Yu. F; Mikhailov, V; Miller, H. R; Morrill, A. C; Noble, J; O'Brien, P. T; Oswalt, T. D; Pebley, S. P; Pfeiffer, M; Pronik, V. I; Qian, B. C; Robertson, J. W; Robinson, A.; Rumstay, K. S; Schmoll, J; Sergeev, S. G; Sergeeva, E. A; Shapovalova, A. I; Skillman, D. R; Snedden, S. A; Soundararajaperumal, S; Stirpe, G. M; Tao, J; Turner, G. W; Wagner, R. M; Wagner, S. J; Wei, J. Y; Wu, H.; Zheng, W; Zou, Z. L (The American Astronomical Society, 1998-04)
    Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-1995 are presented. The broadband fluxes (B, V, R, and I), the spectrophotometric optical continuum flux F lambda (5177 A), and the integrated ...
  • 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 ...
  • Very large baseline array observations of Mrk 6: probing the jet–lobe connection 
    Kharb, P; O'Dea, C. P; Baum, S. A; Hardcastle, M. J; Dicken, D; Croston, J. H; Mingo, B; Noel-Storr, J (Oxford University Press on behalf of the Royal Astronomical Society, 2014-06-01)
    We present the results of high-resolution VLBI (very long baseline interferometry) observations at 1.6 and 4.9 GHz of the radio-loud Seyfert galaxy, Mrk 6. These observations are able to detect a compact radio core in this ...
  • The WEBT campaign to observe AO 0235+16 in the 2003-2004 observing season. Results from radio-to-optical monitoring and XMM-Newton observations 
    Raiteri, C. M; Villata, M; Ibrahimov, M. A; Larionov, V. M; Kadler, M; Aller, H. D; Aller, M. F; Kovalev, Y. Y; Lanteri, L; Nilsson, K; Papadakis, I. E; Pursimo, T; Romero, G. E; Teräsranta, H; Tornikoski, M; Arkharov, A. A; Barnaby, D; Berdyugin, A; Böttcher, M; Byckling, K; Carini, M. T; Carosati, D; Cellone, S. A; Ciprini, S; Combi, J. A; Crapanzano, S; Crowe, R; di Paola, A; Dolci, M; Fuhrmann, L; Gu, M; Hagen-Thorn, V. A; Hakala, P; Impellizzeri, V; Jorstad, S; Kerp, J; Kimeridze, G. N; Kovalev, Yu. A; Kraus, A; Krichbaum, T. P; Kurtanidze, O. M; Lähteenmäki, A; Lindfors, E; Mingaliev, M. G; Nesci, R; Nikolashvili, M. G; Ohlert, J; Orio, M; Ostorero, L; Pasanen, M; Pati, A. K; Poteet, C; Ros, E; Ros, J. A; Shastri, P; Sigua, L. A; Sillanpää, A; Smith, N; Takalo, L. O; Tosti, G.; Vasileva, A; Wagner, S. J; Walters, R; Webb, J. R; Wills, W; Witzel, A; Xilouris, E (EDP Sciences, 2005-07)
    A multiwavelength campaign to observe the BL Lac object AO 0235+16 (z=0.94) was set up by the Whole Earth Blazar Telescope (WEBT) collaboration during the observing seasons 2003-2004 and 2004-2005, involving radio, near-IR ...
  • X-Ray variability of active galactic nuclei in the soft and hard X-Ray bands 
    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 ...

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