Astrophysical: Quasars

  • Publication
    A Study of the Correlation between the Amplification of the Fe Kα Line and the X-Ray Continuum of Quasars due to Microlensing
    The observed enhancement of the Fe Kα line in three gravitationally lensed QSOs (MG J0414+0534, QSO 2237+0305, and H1413+117) is interpreted in terms of...
  • Publication
    A sudden fade of OJ 287
    Optical and radio observations of the BL Lacertae object OJ 287 made early in 1989 show a sudden fade in both wavelength ranges. From January to early April the...
  • Publication
    A Survey of Extended Radio Jets in Active Galactic Nuclei with Chandra and the Hubble Space Telescope: First Results
    We present the first results from an X-ray and optical survey of a sample of radio jets in active galactic nuclei with Chandra and the Hubble Space Telescope...
  • Publication
    A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey. II. Discovery of Three Additional Quasars at z>6
    We present the discovery of three new quasars at z>6 in ~ 1300 deg2 of Sloan Digital Sky Survey imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3...
  • Publication
    A young, dusty, compact radio source within a Lyα halo
    We report here on the discovery of a red quasar, J004929.4+351025.7 at a redshift of z = 2.48, situated within a large Lyα emission-line halo. The radio...
  • Publication
    Absence of nuclear polycyclic aromatic hydrocarbon emission from a compact starburst: The case of the type-2 quasar Mrk 477
    Mrk 477 is the closest type-2 quasar, at a distance of 163 Mpc. This makes it an ideal laboratory for studying the interplay between nuclear activity and star...
  • Publication
    Absence of radio-bright dominance in a near-infrared selected sample of red quasars
    Context. The dichotomy between red and blue quasars is still an open question. It is debated whether red quasars are simply blue quasars that are observed at...
  • Publication
    Absorption signatures of warm-hot gas at low redshift: broad H I Lyα absorbers
    We investigate the physical state of H I absorbing gas at low redshift (z = 0.25) using a subset of cosmological, hydrodynamic simulations from the...
  • Publication
    Absorption signatures of warm-hot gas at low redshift: O VI
    We investigate the origin and physical properties of O VI absorbers at low redshift (z= 0.25) using a subset of cosmological, hydrodynamical simulations from...