Now showing items 1-12 of 12

    • Discovery of Candidate H2O Disk Masers in Active Galactic Nuclei and Estimations of Centripetal Accelerations 

      Greenhill, Lincoln Jared; Kondratko, Paul T.; Moran, James M.; Tilak, Avanti (IOP Publishing, 2009)
      Based on spectroscopic signatures, about one-third of known H2O maser sources in active galactic nuclei (AGNs) are believed to arise in highly inclined accretion disks around central engines. These “disk maser candidates” ...
    • The Discovery of H2O Maser Emission in Seven AGN and at High Velocities in the Circinus Galaxy 

      Greenhill, Lincoln Jared; Kondratko, P. T.; Lovell, J. E. J.; Kuiper, T. B. H.; Moran, James M.; Jauncey, D. L.; Baines, G. P. (IOP Publishing, 2002)
      We report the discovery of H2O maser emission at 1.35 cm wavelength in seven active galactic nuclei (at distances up to < 80 Mpc) during a survey conducted at the 70-m diameter antenna of the NASA Deep Space Network near ...
    • Discovery of Water Maser Emission in Eight AGNs with 70 m Antennas of NASA’s Deep Space Network 

      Kondratko, P. T.; Greenhill, Lincoln Jared; Moran, James M.; Lovell, J. E. J.; Kuiper, T. B. H.; Jauncey, D. L.; Cameron, L. B.; Gomez, J. F.; Garcia‐Miro, C.; Moll, E.; de Gregorio‐Monsalvo, I.; Jimenez‐Bailon, E. (IOP Publishing, 2006)
      We report the discovery of water maser emission in eight active galactic nuclei (AGN) with the 70-m NASA Deep Space Network (DSN) antennas at Tidbinbilla, Australia and Robledo, Spain. The positions of the newly discovered ...
    • Discovery of Water Maser Emission in Five AGNs and a Possible Correlation Between Water Maser and Nuclear 2–10 keV Luminosities 

      Kondratko, Paul T.; Greenhill, Lincoln Jared; Moran, James M. (IOP Publishing, 2006)
      We report the discovery of water maser emission in five active galactic nuclei (AGN) with the 100-m Green Bank Telescope (GBT). The positions of the newly discovered masers, measured with the VLA, are consistent with the ...
    • Evidence for a Geometrically Thick Self‐Gravitating Accretion Disk in NGC 3079 

      Kondratko, Paul T.; Greenhill, Lincoln Jared; Moran, James M. (IOP Publishing, 2005)
      We have mapped, for the first time, the full velocity extent of the water maser emission in NGC 3079. The largely north-south distribution of emission, aligned with a kpc-scale molecular disk, and the segregation of blue- ...
    • A Green Bank Telescope Search for Water Masers in Nearby Active Galactic Nuclei 

      Braatz, J. A.; Henkel, C.; Greenhill, Lincoln Jared; Moran, James M.; Wilson, A. S. (IOP Publishing, 2004)
      Using the Green Bank Telescope, we have conducted a survey for 1.3 cm water maser emission toward the nuclei of nearby active galaxies, the most sensitive large survey for H2O masers to date. Among 145 galaxies observed, ...
    • A Search for H 2 O Maser Emission in Southern Active Galactic Nuclei and Star‐forming Galaxies: Discovery of a Maser in the Edge‐on Galaxy IRAS F01063?8034 

      Greenhill, Lincoln Jared; Ellingsen, S.; Norris, R.; McGregor, P.; Gough, R.; Sinclair, M.; Rayner, D.; Phillips, C.; Herrnstein, J.; Moran, James M. (IOP Publishing, 2002)
      We report the cumulative results of five surveys for H2O maser emission at 1.35 cm wavelength in 131 active galactic nuclei (AGNs) and star-forming galaxies, conducted at the Parkes Observatory between 1993 and 1998. We ...
    • Stacked reverberation mapping 

      Fine, S.; Shanks, T.; Green, P.; Kelly, B. C.; Croom, S. M.; Webster, R. L.; Berger, Edo; Chornock, R.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Price, P. A. (Oxford University Press (OUP), 2013)
      Over the past 20 years reverberation mapping has proved one of the most successful techniques for studying the local (< 1 pc) environment of super-massive black holes that drive active galactic nuclei. Key successes of ...
    • Steps toward determination of the size and structure of the broad-line region in active nuclei. 7: Variability of the optical spectrum of NGC 5548 over years 

      Peterson, B. M.; Berlind, Perry; Bertram, R.; Bochkarev, N. G.; Bond, D.; Brotherton, M. S.; Busler, J. R.; Chuvaev, K. K.; Cohen, R. D.; Dietrich, M.; Elvis, Martin S.; Filippenko, A. V.; Foltz, C. B.; Garnavich, P. M.; Ho, L. C.; Horine, E.; Horne, K.; Huchra, J; Kollatschny, W.; Korista, K. T.; Malkan, M. A.; Matheson, T.; Mignoli, M.; Morris, S. L.; Nazarova, L.; Penfold, J.; Peters, J.; Pogge, R. W.; Pronik, V. I.; Rush, B.; Sergeev, S. G.; Shapovalova, A. I.; Shields, J. C.; Stirpe, G. M.; Tokarz, S.; Wagner, Rudolf; Weymann, R. J.; White, R. J.; Wilkes, Belinda Jane; Wills, D.; Wills, B. J.; Winge, C.; Younger, P. F. (IOP Publishing, 1994)
      We report on the results of a continuation of a large monitoring program of optical spectroscopy of the Seyfert 1 galaxy NGC 5548. The new observations presented here were obtained between 1990 December and 1992 October, ...
    • The variability of the spectrum of Arakelian 120. II - Evidence for a small broad line emitting region 

      Peterson, B. M.; Meyers, K. A.; Carpriotti, E. R.; Foltz, C. B.; Wilkes, Belinda Jane; Miller, H. R. (IOP Publishing, 1985)
      The results of four years of spectroscopic and photometric observations of the Seyfert galaxy Akn 120 are reported. The observations were carried out using the image dissector scanner attached to the Perkins 1.8-meter ...
    • A Warped Accretion Disk and Wide‐Angle Outflow in the Inner Parsec of the Circinus Galaxy 

      Greenhill, Lincoln Jared; Booth, R. S.; Ellingsen, S. P.; Herrnstein, J. R.; Jauncey, D. L.; McCulloch, P. M.; Moran, James M.; Norris, R. P.; Reynolds, J. E.; Tzioumis, A. K. (IOP Publishing, 2003)
      We present the first VLBI maps of H2O maser emission (λ1.3 cm) in the nucleus of the Circinus Galaxy, constructed from data obtained with the Australia Telescope Long Baseline Array. The maser emission traces a warped, ...
    • X-ray Luminosity and Absorption Column Fluctuations in the H2O Maser Galaxy NGC 4258 from Weeks to Years 

      Fruscione, Antonella; Greenhill, Lincoln Jared; Filippenko, Alexei V.; Moran, James M.; Herrnstein, James R.; Galle, Elizabeth (IOP Publishing, 2005)
      We report monitoring of the 0.3–10 keV spectrum of NGC 4258 with the the XMM-Newton Observatory at five epochs over 1.5 years. We also report reprocessing of an overlapping four-epoch series of archival Chandra observations ...