What Is The Numerically Converged Amplitude of MHD Turbulence in Stratified Shearing Boxes? (2009)
Shi, Ji-Ming, Krolik, Julian H., Hirose, Shigenobu
We study the properties of the turbulence driven by the magnetorotational instability (MRI) in a stratified shearing box with outflow boundary conditions and an equation of state determined by...
Hirose, Shigenobu, Blaes, Omer, Krolik, Julian H.
We present the results of a series of radiation-MHD simulations of a local patch of an accretion disk, with fixed vertical gravity profile but with different surface mass densities and a broad range...
Host Galaxies of Luminous Type 2 Quasars at z ~ 0.5 (2009)
Liu, Xin, Zakamska, Nadia L., Greene, Jenny E., Strauss, Michael A., Krolik, Julian H., Heckman, Timothy M.
We present deep Gemini GMOS optical spectroscopy of nine luminous quasars at redshifts z ~ 0.5, drawn from the SDSS type 2 quasar sample. Our targets were selected to have high intrinsic luminosities...
GRMHD prediction of coronal variability in accreting black holes (2009)
Noble, Scott C., Krolik, Julian H.
On the basis of data from an energy-conserving 3D general relativistic MHD simulation, we predict the statistical character of variability in the coronal luminosity from accreting black holes. When...
Transport of Large Scale Poloidal Flux in Black Hole Accretion (2009)
Beckwith, Kris, Hawley, John F., Krolik, Julian H.
We report on a global, three-dimensional GRMHD simulation of an accretion torus embedded in a large scale vertical magnetic field orbiting a Schwarzschild black hole. This simulation investigates how...
X-ray Polarization from Black Holes in the Thermal State (2009)
Schnittman, Jeremy D., Krolik, Julian H.
We present new calculations of X-ray polarization from black hole accretion disks in the thermally-dominated state, using a Monte-Carlo ray-tracing code in full general relativity. In contrast to...
X-ray Polarization from Accreting Black Holes: II. The Thermal State (2009)
Schnittman, Jeremy D., Krolik, Julian H.
We present new calculations of X-ray polarization from black hole (BH) accretion disks in the thermally-dominated state, using a Monte-Carlo ray-tracing code in full general relativity. In contrast...
SDSSJ092712.65+294344.0: NGC 1275 at z=0.7? (2008)
Heckman, Timothy M., Krolik, Julian H., Moran, Sean M., Schnittman, Jeremy, Gezari, Suvi
SDSSJ092712.65+294344.0 was identified by the SDSS as a quasar, but has the unusual property of having two emission line systems offset by 2650 km/s. One of these contains the usual combination of...
Radiation-Dominated Disks Are Thermally Stable (2008)
Hirose, Shigenobu, Krolik, Julian H., Blaes, Omer
When the accretion rate is more than a small fraction of Eddington, the inner regions of accretion disks around black holes are expected to be radiation-dominated. However, in the alpha-model, these...
Direct calculation of the radiative efficiency of an accretion disk around a black hole (2008)
Noble, Scott C., Krolik, Julian H., Hawley, John F.
Numerical simulation of magnetohydrodynamic (MHD) turbulence makes it possible to study accretion dynamics in detail. However, special effort is required to connect inflow dynamics (dependent largely...
Mid-infrared spectra of optically selected type 2 quasars (2008)
Zakamska, Nadia L., Gomez, Laura, Strauss, Michael A., Krolik, Julian H.
Type 2 quasars are luminous Active Galactic Nuclei whose central engines are seen through large amounts of gas and dust. We present Spitzer spectra of twelve type 2 quasars selected on the basis of...
Detailed Atmosphere Model Fits to Disk-Dominated ULX Spectra (2008)
We have chosen 6 Ultra-Luminous X-ray sources from the {\it XMM-Newton} archive whose spectra have high signal-to-noise and can be fitted solely with a disk model without requiring any power-law...
The Infrared Afterglow of Supermassive Black Hole Mergers (2008)
Schnittman, Jeremy D., Krolik, Julian H.
We model the spectra and light curves of circumbinary accretion disks during the time after the central black holes merge. The most immediate effect of this merger is the dissipation of energy in the...
Radiation Pressure Supported AGN Tori with Hard X-Ray and Stellar Heating (2008)
Shi, Jiming, Krolik, Julian H.
The dynamics and structure of toroidal obscuration around AGN remain uncertain and controversial. In this paper we extend earlier work on the dynamical role of infrared radiation pressure by adding...
Measuring the Fraction of Obscured Quasars by the Infrared Luminosity of Unobscured Quasars (2008)
Treister, Ezequiel, Krolik, Julian H., Dullemond, Cornelis
Recent work has suggested that the fraction of obscured AGN declines with increasing luminosity, but it has been difficult to quantify this trend. Here, we attempt to measure this fraction as a...
Space density of optically-selected type 2 quasars (2008)
Reyes, Reinabelle, Zakamska, Nadia L., Strauss, Michael A., Green, Joshua, Krolik, Julian H., Shen, Yue, ...
Type 2 quasars are luminous active galactic nuclei (AGN) whose central regions are obscured by large amounts of gas and dust. In this paper, we present a catalog of type 2 quasars from the Sloan...
Measuring the fraction of obscured quasars by the infrared luminosity of unobscured quasars (2008)
Treister, Ezequiel, Krolik, Julian H., Dullemond, Cornelis
Recent work has suggested that the fraction of obscured AGNs declines with increasing luminosity, but it has been difficult to quantify this trend. Here we attempt to measure this fraction as a...
Global MHD Simulation of the Inner Accretion Disk in a Pseudo-Newtonian Potential (2007)
John F. Hawley, Julian H. Krolik
We present a detailed three dimensional magnetohydrodynamic (MHD) simulation describing the inner region of a disk accreting onto a black hole. To avoid the technical complications of general...
John F. Hawley, Julian H. Krolik
New three dimensional magnetohydrodynamic simulations of accretion disk dynamics in a pseudo-Newtonian Paczy'nski-Wiita potential are presented. These have finer resolution in the inner disk...
Beckwith, Kris, Hawley, John F., Krolik, Julian H.
Because the magneto-rotational instability is capable of exponentially amplifying weak preexisting magnetic fields, it might be hoped that the character of the magnetic field in accretion disks is...
Thermodynamics of an Accretion Disk Annulus with Comparable Radiation and Gas Pressure (2007)
Krolik, Julian H., Hirose, Shigenobu, Blaes, Omer
We explore the thermodynamic and global structural properties of a local patch of an accretion disk whose parameters were chosen so that radiation pressure and gas pressure would be comparable in...
Surface Structure in an Accretion Disk Annulus with Comparable Radiation and Gas Pressure (2007)
Blaes, Omer, Hirose, Shigenobu, Krolik, Julian H.
We have employed a 3-d energy-conserving radiation MHD code to simulate the vertical structure and thermodynamics of a shearing box whose parameters were chosen so that the radiation and gas...
AGN Obscuring Tori Supported by Infrared Radiation Pressure (2007)
Explicit 2-d axisymmetric solutions are found to the hydrostatic equilibrium, energy balance, and photon diffusion equations within obscuring tori around active galactic nuclei. These solutions...
The relationship between accretion disks and jets (2007)
John F. Hawley, Julian H. Krolik, Shigenobu Hirose
Recent results are reported from a program of large-scale numerical simulation of accretion and jet ows utilizing a code that computes 3-d MHD in full general relativity. We find that out ows arise...
Light Curves from an MHD Simulation of a Black Hole Accretion Disk (2006)
Schnittman, Jeremy D., Krolik, Julian H., Hawley, John F.
We use a relativistic ray-tracing code to calculate the light curves observed from a global general relativistic magneto-hydrodynamic simulation of an accretion flow onto a Schwarzschild black hole....
Estimating the Radiative Efficiency of Magnetized Accretion Disks Around Black Holes (2006)
Beckwith, Kris, Hawley, John F., Krolik, Julian H.
Simulations of black hole accretion have shown that magnetic stresses are present near and inside the innermost stable circular orbit (ISCO). This finding suggests that such flows may be more...
Zakamska, Nadia L., Strauss, Michael A., Krolik, Julian H., Ridgway, Susan E., Schmidt, Gary D., Smith, Paul S., ...
Type II quasars are luminous Active Galactic Nuclei whose centers are obscured by large amounts of gas and dust. In this paper we present 3-band HST images of nine type II quasars with redshifts 0.2...
The Weak Field Limit of the Magnetorotational Instability (2006)
Krolik, Julian H., Zweibel, Ellen G.
We investigate the behavior of the magneto-rotational instability in the limit of extremely weak magnetic field, i.e., as the ratio of ion cyclotron frequency to orbital frequency (X) becomes small....
Hosts of Type II Quasars: an HST Study (2006)
Zakamska, Nadia L., Strauss, Michael A., Krolik, Julian H., Ridgway, Susan E., Schmidt, Gary D., Smith, Paul S., ...
Type II quasars are luminous Active Galactic Nuclei whose centers are obscured by large amounts of gas and dust. In this contribution we present 3-band HST images of nine type II quasars with...
Magnetically Driven Jets in the Kerr Metric (2005)
Hawley, John F., Krolik, Julian H.
We compute a series of three-dimensional general relativistic magnetohydrodynamic simulations of accretion flows in the Kerr metric to investigate the properties of the unbound outflows that result....
Hirose, Shigenobu, Krolik, Julian H., Stone, James M.
(shortened) We calculate the vertical structure of a local patch of an accretion disk in which heating by dissipation of MRI-driven MHD turbulence is balanced by radiative cooling. Heating, radiative...
Active Galactic Nuclei in the Sloan Digital Sky Survey: II. Emission-Line Luminosity Function (2005)
Hao, Lei, Strauss, Michael A., Fan, Xiaohui, Tremonti, Christy A., Schlegel, David J., Heckman, Timothy M., ...
The emission line luminosity function of active galactic nuclei (AGN) is measured from about 3000 AGN included in the main galaxy sample of the Sloan Digital Sky Survey within a redshift range of $0
Active Galactic Nuclei in the Sloan Digital Sky Survey: I. Sample Selection (2005)
Hao, Lei, Strauss, Michael A., Tremonti, Christy A., Schlegel, David J., Heckman, Timothy M., Kauffmann, Guinevere, ...
We have compiled a large sample of low-redshift active galactic nuclei (AGN) identified via their emission line characteristics from the spectroscopic data of the Sloan Digital Sky Survey. Since...
Zakamska, Nadia L., Schmidt, Gary D., Smith, Paul S., Strauss, Michael A., Krolik, Julian H., Hall, Patrick B., ...
Active galactic nuclei in the sloan digital sky survey. I. Sample selection (2005)
Hao, Lei, Strauss, Michael A., Tremonti, Christy A., Schlegel, David J., Heckman, Timothy M., Kauffmann, Guinevere, ...
Active galactic nuclei in the sloan digital sky survey. II. Emission-line luminosity function (2005)
Hao, Lei, Strauss, Michael A., Fan, Xiaohui, Tremonti, Christy A., Schlegel, David J., Heckman, Timothy M., ...
Active Galactic Nuclei in the Sloan Digital Sky Survey. I. Sample Selection (2005)
Hao, Lei, Strauss, Michael A., Tremonti, Christy A., Schlegel, David J., Heckman, Timothy M., Kauffmann, Guinevere, ...
Candidate Type II Quasars from the SDSS: III. Spectropolarimetry Reveals Hidden Type I Nuclei (2004)
Zakamska, Nadia L., Schmidt, Gary D., Smith, Paul S., Strauss, Michael A., Krolik, Julian H., Hall, P. B., ...
We have conducted spectropolarimetry of 12 type II (obscured) quasar candidates selected from the spectroscopic database of the Sloan Digital Sky Survey based on their emission line properties....
Krolik, Julian H., Hawley, John F., Hirose, Shigenobu
This paper continues the analysis of a set of general relativistic 3D MHD simulations of accreting tori in the Kerr metric with different black hole spins. We focus on bound matter inside the initial...
The origin and nature of Ultra-Luminous X-ray sources (ULXs) is a contentious and controversial topic. There are ongoing debates about the masses of the objects responsible, their sources of mass for...
Magnetically Driven Accretion in the Kerr Metric III: Unbound Outflows (2004)
De Villiers, Jean-Pierre, Hawley, John F., Krolik, Julian H., Hirose, Shigenobu
We have carried out fully relativistic numerical simulations of accretion disks in the Kerr metric. In this paper we focus on the unbound outflows that emerge self-consistently from the accretion...
Candidate Type II Quasars from the Sloan Digital Sky Survey: II. From Radio to X-Rays (2004)
Zakamska, Nadia L., Strauss, Michael A., Heckman, Timothy M., Ivezic, Zeljko, Krolik, Julian H.
Type II quasars are luminous AGNs whose central engines and broad-line regions are obscured by intervening material; such objects only recently have been discovered in appreciable numbers. We study...
BL Lac X-ray Spectra: simpler than we thought (2004)
Perlman, Eric S., Daugherty, Timothy, Koratkar, Anuradha, Madejski, Grzegorz, Andersson, Karl, Krolik, Julian H., ...
We report results from {\it XMM-Newton} observations of thirteen X-ray bright BL Lacertae objects, selected from the {\it Einstein} Slew Survey sample. The spectra are generally well fit by power-law...
Magnetically Driven Accretion Flows in the Kerr Metric II: Structure of the Magnetic Field (2003)
Hirose, Shigenobu, Krolik, Julian H., De Villiers, Jean-Pierre, Hawley, John F.
We present a detailed analysis of the magnetic field structure found in general relativistic 3D MHD simulations of accreting tori in the Kerr metric with different black hole spins. Among the...
Type II Quasars from the SDSS (2003)
Zakamska, Nadia L., Strauss, Michael A., Krolik, Julian H., Heckman, Timothy M.
Type II quasars are suggested by unification models of Active Galactic Nuclei as luminous analogs of Seyfert 2 galaxies. A number of different methods have been used hitherto to discover type II...
Zakamska, Nadia L., Strauss, Michael A., Krolik, Julian H., Collinge, M. J., Hall, P. B., Hao, L., ...
Type II quasars are the long-sought luminous analogs of type II (narrow emission line) Seyfert galaxies, suggested by unification models of active galactic nuclei (AGN) and postulated to account for...
Magnetically Driven Accretion Flows in the Kerr Metric I: Models and Overall Structure (2003)
De Villiers, Jean-Pierre, Hawley, John F., Krolik, Julian H.
This is the first in a series of papers that investigate the properties of accretion flows in the Kerr metric through three-dimensional, general relativistic magnetohydrodynamic simulations of tori...
Reichard, Timothy A., Richards, Gordon T., Schneider, Donald P., Hall, Patrick B., Tolea, Alin, Krolik, Julian H., ...
We present a catalog of 224 broad absorption line quasars (BALQSOs) from the Sloan Digital Sky Survey's Early Data Release Quasar Catalog, including a relatively complete and homogeneous subsample of...
Broad Absorption Line Quasars in the Early Data Release from the Sloan Digital Sky Survey (2002)
Tolea, Alin, Krolik, Julian H., Tsvetanov, Zlatan
A new broad absorption line quasar (BAL) sample is derived from the first data released by the Sloan Digital Sky Survey. With 116 objects, it is the largest BAL sample yet assembled. Over the...
High Resolution X-ray Spectroscopy and the Nature of Warm Absorbers in AGN (2002)
Although soft X-ray absorption features in AGN were discovered almost ten years ago, the nature and location of the gas creating them has remained controversial. However, by making use of the...
Where is the Inner Edge of an Accretion Disk Around a Black Hole? (2002)
Krolik, Julian H., Hawley, John F.
What is meant by the "inner edge" of an accretion disk around a black hole depends on the property that defines the edge. We discuss four such definitions using data from recent high-resolution...
Unusual Broad Absorption Line Quasars from the Sloan Digital Sky Survey (2002)
Hall, Patrick B., Anderson, Scott F., Strauss, Michael A., York, Donald G., Richards, Gordon T., Fan, Xiaohui, ...
Sloan Digital Sky Survey: early data release (2002)
Stoughton, Chris, Lupton, Robert H., Bernardi, Mariangela, Blanton, Michael R., Burles, Scott M., Castander, Francisco J., ...
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of ≈ 106 galaxies,...
Sloan Digital Sky Survey: early data release (2002)
Stoughton, Chris, Lupton, Robert H., Bernardi, Mariangela, Blanton, Michael R., Burles, Scott M., Castander, Francisco J., ...
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of ≈ 106 galaxies,...
UV Imaging Polarimetry of the peculiar Seyfert 2 galaxy Mrk 477 (2001)
Kishimoto, Makoto, Kay, Laura E., Antonucci, Robert, Hurt, Todd W., Cohen, Ross D., Krolik, Julian H.
We present the results of UV imaging polarimetry of the Seyfert 2 galaxy Mrk 477 taken by the Faint Object Camera onboard the Hubble Space Telescope (HST). From a previous HST UV image (lambda ~...
Hawley, John F., Krolik, Julian H.
New three dimensional magnetohydrodynamic simulations of accretion disk dynamics in a pseudo-Newtonian Paczynski-Wiita potential are presented. These have finer resolution in the inner disk than any...
UV Imaging Polarimetry of the Seyfert 2 Galaxy Mrk 3 (2001)
Kishimoto, Makoto, Kay, Laura E., Antonucci, Robert, Hurt, Todd W., Cohen, Ross D., Krolik, Julian H.
We present UV imaging polarimetry data of the Seyfert 2 galaxy Mrk 3 taken by the Hubble Space Telescope. The polarized flux is found to be extended to ~1 kpc from the nucleus, and the position...
Blaes, Omer, Hubeny, Ivan, Agol, Eric, Krolik, Julian H.
We fit general relativistic, geometrically thin accretion disk models with non-LTE atmospheres to near simultaneous multiwavelength data of 3C~273, extending from the optical to the far ultraviolet....
Warm Absorbers in AGN: A Multi-Temperature Wind (2001)
Krolik, Julian H., Kriss, Gerard A.
Although soft X-ray absorption features in AGN were discovered almost ten years ago, the nature and location of the gas creating them has remained controversial. Guided by the results of recent...
X-ray Destruction of Dust Along the Line of Sight to Gamma-Ray Bursts (2001)
Fruchter, Andrew S., Krolik, Julian H., Rhoads, James E.
We show that if all gamma-ray bursts emit X-rays in a way similar to those observed by BeppoSax, much of the extinction along the line of sight in the host galaxy of the burst can be destroyed. Two...
Hubeny, Ivan, Blaes, Omer, Krolik, Julian H., Agol, E.
We extend our models of the vertical structure and emergent radiation field of accretion disks around supermassive black holes described in previous papers of this series. Our models now include both...
Magnetic Stresses at the Inner Edges of Accretion Disks Around Black Holes (2001)
For the past twenty-five years, nearly all analyses of accretion disk dynamics have assumed that stress inside the disk is locally proportional to pressure (the "alpha-model") and that this stress...
Systematic Errors in the Estimation of Black Hole Masses by Reverberation Mapping (2000)
The mass of the central black hole in many active galactic nuclei has been estimated on the basis of the assumption that the dynamics of the broad emission line gas are dominated by the gravity of...
Magnetic Extraction of Spin Energy from a Black Hole (2000)
Numerous variations have been proposed on the original suggestion by Blandford and Znajek that magnetic fields could be used to extract rotational energy from black holes. A new categorization of...
Global MHD Simulation of the Inner Accretion Disk in a Pseudo-Newtonian Potential (2000)
Hawley, John F., Krolik, Julian H.
We present a detailed three dimensional magnetohydrodynamic (MHD) simulation describing the inner region of a disk accreting onto a black hole. To avoid the technical complications of general...
Sincell, Mark W., Krolik, Julian H.
We present an improved calculation of the vertical structure and ultraviolet spectrum of a dissipative accretion disk in an AGN. We calculate model spectra in which the viscous stress is proportional...
Physical Characteristics of the Spectral States of Galactic Black Holes (1997)
Poutanen, Juri, Krolik, Julian H., Ryde, Felix
Using simple analytical estimates we show how the physical parameters characterizing different spectral states of the galactic black hole candidates can be determined using spectral data presently...
Thermal conduction in accretion disk coronae (1997)
Maciolek-Niedzwiecki, Andrzej, Krolik, Julian H., Zdziarski, Andrzej A.
We study the effects of thermal conduction in a hot, active corona above an accretion disk. We assume that all of the dissipative heating takes place in the corona. We find that the importance of...
Sincell, Mark W., Krolik, Julian H.
Motivated by recent work indicating that the UV continuum in AGN may be produced by reradiation of energy absorbed from X-rays irradiating an accretion disk, we present a calculation of the vertical...
A Unified View of How the Study of Emission Lines Furthers our Knowledge of AGN (1996)
A global view is given of how emission lines have been, and may in the future, be used to enhance our understanding of AGN. Lines from the microwave to the X-ray bands all contribute. Although we...
Self-Shielding of X-rays and Gamma-Rays in Compact Sources (1996)
Illarionov, Andrei F., Krolik, Julian H.
It is generally supposed that when the "compactness" $l \equiv L\sigma_T/(r m_e c^3)$ in photons above the pair-production threshold is large, few $\gamma$-rays can escape. We demonstrate that even...
Observable Properties of X-ray Heated Winds in AGN: Warm Reflectors and Warm Absorbers (1995)
Krolik, Julian H., Kriss, Gerard A.
When an AGN is obscured, the warm reflecting gas nearby can be seen by a combination of bremsstrahlung, intrinsic line emission, and reflection of the nuclear continuum, both by electron scattering...
The Inverse Compton Thermostat in Hot Plasmas Near Accreting Black Holes (1995)
Pietrini, Paola, Krolik, Julian H.
The hard X-ray spectra of accreting black holes systems are generally well-fit by thermal Comptonization models with temperatures $\sim 100$ keV. We demonstrate why, over many orders of magnitude in...
Interpolation of Irregularly Sampled Data Series - A Survey (1995)
. Many astronomical observations, including spectra and time series, consist of irregularly sampled data series, the analysis of which is more complicated than that of regularly spaced data sets....