General Relativistic MHD Jets (2009)
Magnetic fields connecting the immediate environs of rotating black holes to large distances appear to be the most promising mechanism for launching relativistic jets, an idea first developed by...
The Effects of Magnetic Fields and Inhomogeneities on Accretion Disk Spectra and Polarization (2009)
Davis, S. W., Blaes, O. M., Hirose, S., Krolik, J. H.
We present the results of one and three-dimensional radiative transfer calculations of polarized spectra emerging from snapshots of radiation magnetohydrodynamical simulations of the local vertical...
G. A. Kriss, B. R. Espey, J. H. Krolik, Z. Tsvetanov, W. Zheng, A. F. Davidsen
We observed the Seyfert 1 galaxy NGC 3516 twice during the flight of Astro-2 using the Hopkins Ultraviolet Telescope aboard the space shuttle Endeavour in March 1995. Simultaneous X-ray observations...
Making black holes visible: accretion, radiation, and jets (2007)
With the fundamental stress mechanism of accretion disks identified--correlated MHD turbulence driven by the magneto-rotational instability--it has become possible to make numerical simulations of...
Accretion and Ejection--The GR/MHD View (2006)
The inward flow of matter through accretion disks is driven by MHD turbulence. Global general relativistic MHD simulations shed quantitative light on this process, revealing a number of aspects of...
Penetrating the Deep Cover of Compton Thick Active Galactic Nuclei (2006)
Levenson, N. A., Heckman, T. M., Krolik, J. H., Weaver, K. A., Zycki, P. T.
We analyze observations obtained with the Chandra X-ray Observatory of bright Compton thick active galactic nuclei (AGNs), those with column densities in excess of 1.5 x 10^{24} cm^{-2} along the...
Magnetic pressure support and accretion disk spectra (2006)
Blaes, O. M., Davis, S. W., Hirose, S., Krolik, J. H., Stone, J. M.
Stellar atmosphere models of ionized accretion disks have generally neglected the contribution of magnetic fields to the vertical hydrostatic support, although magnetic fields are widely believed to...
Clavel, J., Schulz, B., Altieri, B., Barr, P., Alloin, D., ...
Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 micron spectrum....
Non-LTE Spectra of Accretion Disks Around Intermediate-Mass Black Holes (2005)
Hui, Y., Krolik, J. H., Hubeny, I.
We have calculated the structures and the emergent spectra of stationary, geometrically thin accretion disks around 100 and 1000 M_sun black holes in both the Schwarzschild and extreme Kerr metrics....
Photoionization Modeling and the K Lines of Iron (2004)
Kallman, T. R., Palmeri, P., Bautista, M. A., Mendoza, C., Krolik, J. H.
We calculate the efficiency of iron K line emission and iron K absorption in photoionized models using a new set of atomic data. These data are more comprehensive than those previously applied to the...
A selection of results from the general relativistic MHD accretion simulations described in the previous talk are presented. We find that the magnetic field strength increases sharply with decreasing...
Turner, N. J., Stone, J. M., Krolik, J. H., Sano, T.
We examine the small-scale dynamics of black hole accretion disks in which radiation pressure exceeds gas pressure. Local patches of disk are modeled by numerically integrating the equations of...
Extreme X-ray Iron Lines in Active Galactic Nuclei (2002)
Levenson, N. A., Krolik, J. H., Zycki, P. T., Heckman, T. M., Weaver, K. A., Awaki, H., ...
We analyze X-ray spectra of heavily obscured (N_H > 10^{24} cm^{-2}) active galaxies obtained with Chandra, concentrating on the iron K alpha fluorescence line. We measure very large equivalent...
Extreme BAL Quasars from the Sloan Digital Sky Survey (2001)
Hall, Patrick B., Gunn, J. E., Knapp, G. R., Narayanan, V. K., Strauss, M. A., Anderson, S. F., ...
The Sloan Digital Sky Survey has discovered a population of broad absorption line quasars with various extreme properties. Many show absorption from metastable states of FeII with varying...
Clavel, J., Schulz, B., Altieri, B., Barr, P., Alloin, D., ...
Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 micron spectrum....
Clavel, J., Schulz, B., Altieri, B., Barr, P., Alloin, D., ...
Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 micron spectrum....
Clavel, J., Schulz, B., Altieri, B., Barr, P., Alloin, D., ...
Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 micron spectrum....
Magnetized Accretion Inside the Marginally Stable Orbit around a Black Hole (1999)
Qualitative arguments are presented to demonstrate that the energy density of magnetic fields in matter accreting onto a black hole inside the marginally stable orbit is automatically comparable to...
O'Brien, P. T., Dietrich, M., Leighly, K., Alloin, D., Clavel, J., Crenshaw, D. M., ...
As part of an extensive multi-wavelength monitoring campaign, the International Ultraviolet Explorer satellite was used to observe the broad-line radio galaxy 3C 390.3 during the period 1994 December...
Dietrich, M., Leighly, K., Alloin, D., Clavel, J., Crenshaw, D. M., ...
As part of an extensive multi-wavelength monitoring campaign, the International Ultraviolet Explorer satellite was used to observe the broad-line radio galaxy 3C 390.3 during the period 1994 December...
A New Equilibrium for Accretion Disks Around Black Holes (1998)
Accretion disks around black holes in which the shear stress is proportional to the total pressure, the accretion rate is more than a small fraction of Eddington, and the matter is distributed...
What is the True Covering Factor of Absorbing Matter in BALQSOs? (1998)
Spectropolarimetry of Broad Absorption Line Quasars (BALQSO's) has demonstrated that the geometry of the absorbing material is far from spherically symmetric. Calculations of accretion disk spectra...
Spectral Tests of Models for Accretion Disks Around Black Holes (1998)
A critical review is presented of the current status of our understanding of the the spectral output of thermally-radiating accretion disks around black holes, with special attention to those around...
Far-UV Observations of NGC 4151 during the ORFEUS-SPAS II Mission (1997)
Espey, B. R., Kriss, G. A., Krolik, J. H., Zheng, W., Tsvetanov, Z., Davidsen, A. F.
We observed the Seyfert 1 galaxy NGC 4151 on eleven occasions at 1-2 day intervals using the Berkeley spectrometer during the ORFEUS-SPAS II mission in 1996 November. The mean spectrum covers...
Weaver, K. A., Krolik, J. H., Pier, E. A.
We report the detection with the Rossi X-ray Timing Explorer of a Compton reflection signature in the Seyfert galaxy MCG-5-23-16. RXTE also resolves the Fe K-alpha fluorescence line with FWHM ~48,000...
Wanders, I., Peterson, B.M., Alloin, D., Ayres, T.R., Clavel, J., Crenshaw, D.M., ...
From 1996 June 10 to July 29, the International Ultraviolet Explorer monitored the Seyfert 1 galaxy NGC 7469 continuously in an attempt to measure time delays between the continuum and emission-line...
HUT Observations of Time-Variable Absorption in NGC 4151 (1997)
We present the results of ultraviolet spectral monitoring of the Seyfert galaxy NGC 4151 performed by the Hopkins Ultraviolet Telescope during the Astro-2 mission. We show how the response of the...
Far-Ultraviolet Observations of NGC 3516 using the Hopkins Ultraviolet Telescope (1996)
Kriss, G. A., Espey, B. R., Krolik, J. H., Tsvetanov, Z., Zheng, W., Davidsen, A. F.
We observed the Seyfert 1 galaxy NGC 3516 twice during the flight of Astro-2 using the Hopkins Ultraviolet Telescope in March 1995. Simultaneous X-ray observations were performed with ASCA. Our...
ASCA Observations of the Composite Warm Absorber in NGC 3516 (1996)
Kriss, G. A., Krolik, J. H., Otani, C., Espey, B. R., Turner, T. J., Kii, T., ...
We obtained X-ray spectra of the Seyfert 1 galaxy NGC~3516 in March 1995 using ASCA. Simultaneous far-UV observations were obtained with HUT on the Astro-2 shuttle mission. The ASCA spectrum shows a...
HST Images of the Seyfert Galaxy NGC 5929 and Its Companion NGC 5930(1) (1993)
Bower, G.A., Wilson, A.S., Mulchaey, J.S., Miley, G.K., Heckman, T.M., Krolik, J.H.
HST Imaging of the Seyfert 2 Galaxy NGC 2110 (1993)
Mulchaey, J.S., Wilson, A.S., Bower, G.A., Heckman, T.M., Krolik, J.H., Miley, G.K.