Publications (101)
The Continuing Slow Decline of AG Pegasi
Scott J. Kenyon, Daniel Proga, Charles D. Keyes
We analyze optical and ultraviolet observations of the symbiotic binary AG Pegasi acquired during 1992-97. The bolometric luminosity of the hot component declined by a factor of 2-…
Dynamical thermal instability in highly supersonic outflows
Tim Waters, Daniel Proga, Randall Dannen +1
Acceleration can change the ionization of X-ray irradiated gas to the point that the gas becomes thermally unstable. Cloud formation, the expected outcome of thermal instability (T…
Magnetohydrodynamic simulations of the collapsar model for early and late evolution of gamma-ray bursts
Daniel Proga
I present results from magnetohydrodynamic (MHD) simulations of a gaseous envelope collapsing onto a black hole. These results support the notion that the collapsar model is one of…
Multiphase, non-spherical gas accretion onto a black hole
Paramita Barai, Daniel Proga, Kentaro Nagamine
(Abridged) We investigate non-spherical behavior of gas accreting onto a central supermassive black hole performing simulations using the SPH code GADGET-3 including radiative cool…
Three-Dimensional Simulations of Dynamics of Accretion Flows Irradiated by a Quasar
Ryuichi Kurosawa, Daniel Proga
We study the axisymmetric and non-axisymmetric, time-dependent hydrodynamics of gas that is under the influence of the gravity of a super massive black hole (SMBH) and the radiatio…
Magnetothermal disk winds in X-ray binaries: poloidal magnetic fields suppress thermal winds
Tim Waters, Daniel Proga
Magnetic, radiation pressure, and thermal driving are the three mechanisms capable of launching accretion disk winds. In X-ray binaries, radiation pressure is often not significant…
The effects of irradiation on the cloud evolution in active galactic nuclei
Daniel Proga, Yan-Fei Jiang, James Stone +2
We report on the first phase of our study of cloud irradiation. We study irradiation by means of numerical, two-dimensional time-dependent radiation-hydrodynamic simulations of a c…
Effects of Opacity Temperature Dependence on Radiatively Accelerated Clouds
Sergei Dyda, Daniel Proga, Christopher S Reynolds
We study how different opacity-temperature scalings affect the dynamical evolution of irradiated gas clouds using time-dependent, radiation-hydrodynamics (rad-HD) simulations. When…
CIV Emission and the Ultraviolet through X-ray Spectral Energy Distribution of Radio-Quiet Quasars
Nicholas E. Kruczek, Gordon T. Richards, S. C. Gallagher +6
In the restframe UV, two of the parameters that best characterize the range of emission-line properties in quasar broad emission-line regions are the equivalent width and the blues…
Discerning the physical origins of cosmological Gamma-ray bursts based on multiple observational criteria: the cases of z=6.7 GRB 080913, z=8.3 GRB 090423, and some short/hard GRBs
Bing Zhang, Bin-Bin Zhang, Francisco J. Virgili +10
(Abridged) The two high-redshift gamma-ray bursts, GRB 080913 at z=6.7 and GRB 090423 at z=8.3, recently detected by Swift appear as intrinsically short, hard GRBs. They could have…
The evolved B[e] star HD 87643 : observations and a radiation driven disk-wind model for B[e] stars
Rene Oudmaijer, Daniel Proga, Janet Drew +1
New high resolution spectroscopic and medium resolution spectropolarimetric data, complemented with optical broad and narrow band imaging, of the B[e] star HD 87643 are presented.…
AGN STORM 2: I. First results: A Change in the Weather of Mrk 817
Erin Kara, Missagh Mehdipour, Gerard A. Kriss +69
We present the first results from the ongoing, intensive, multi-wavelength monitoring program of the luminous Seyfert 1 galaxy Mrk 817. While this AGN was, in part, selected for it…
Effects of Radiation Field Geometry on Line Driven Disc Winds
Sergei Dyda, Daniel Proga
We study line driven winds for models with different radial intensity profiles: standard Shakura-Sunyaev radiating thin discs, uniform intensity discs and truncated discs where dri…
Non-Axisymmetric Line Driven Disc Winds I - Disc Perturbations
Sergei Dyda, Daniel Proga
We study mass outflows driven from accretion discs by radiation pressure due to spectral lines. To investigate non-axisymmetric effects, we use the Athena++ code and develop a new…
The late time evolution of Gamma-Ray Bursts: ending hyperaccretion and producing flares
Daniel Proga, Bing Zhang
We consider the properties of a hyperaccretion model for gamma-ray bursts (GRBs) at the late time when the mass supply rate is expected to decrease with time. We point out that the…
AGN STORM 2: V. Anomalous Behavior of the CIV Light Curve in Mrk 817
Y. Homayouni, Gerard A. Kriss, Gisella De Rosa +49
An intensive reverberation mapping campaign on the Seyfert 1 galaxy Mrk817 using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) revealed significant vari…
Time Variability of Low Angular Momentum Flows Accreting onto Black Holes: A Natural Mechanism For Radiation Flaring
Daniel Proga
We present results from our magnetohydrodynamical simulations of accretion flows onto black holes. Our main focus is the interplay between inflows and related outflows. We consider…
AGN STORM 2. XI. Spectroscopic reverberation mapping of the hot dust in Mrk 817
Hermine Landt, Benjamin D. Boizelle, Michael S. Brotherton +41
The AGN Space Telescope and Optical Reverberation Mapping 2 (STORM 2) campaign targeted Mrk 817 with intensive multi-wavelength monitoring and found its soft X-ray emission to be s…
Anisotropic winds from close-in extra-solar planets
James M. Stone, Daniel Proga
We present two-dimensional hydrodynamic models of thermally driven winds from highly irradiated, close-in extra-solar planets. We adopt a very simple treatment of the radiative hea…
X-ray/UV Campaign on the Mrk 279 AGN Outflow: Constraining Inhomogeneous Absorber Models
Nahum Arav, Jelle Kaastra, Gerard A. Kriss +3
We investigate the applicability of inhomogeneous absorber models in the formation of AGN outflow absorption-troughs. The models we explore are limited to monotonic gradients of ab…
The role of failed accretion disk winds in active galactic nuclei
Margherita Giustini, Daniel Proga
Both observational and theoretical evidence point at outflows originating from accretion disks as fundamental ingredients of active galactic nuclei (AGN). These outflows can have m…
Radiation-Driven Outflows in Active Galactic Nuclei
Daniel Proga, Ryuichi Kurosawa
We review the results from multi-dimensional, time-dependent simulations of gas dynamics in AGN. We will focus on two types of outflows powered by radiation emitted from the AGN ce…
On the Feedback Efficiency of Active Galactic Nuclei
Ryuichi Kurosawa, Daniel Proga, Kentaro Nagamine
(Abridged) We measure and analyze the energy, momentum, and mass feedback efficiencies due to radiation from AGN in relatively large scale outflows. Our measurements are based on t…
Clumpy AGN outflows due to thermal instability
Randall Dannen, Daniel Proga, Tim Waters +1
One of the main mechanisms that could drive mass outflows on parsec scales in AGN is thermal driving. The same X-rays that ionize and heat the plasma are also expected to make it t…
Irradiation of Astrophysical Objects - SED and Flux Effects on Thermally Driven Winds
Sergei Dyda, Randall Dannen, Tim Waters +1
We develop a general method for the self consistent calculation of the hydrodynamics of an astrophysical object irradiated by a radiation field with an arbitrary strength and spect…
Theory of Outflows in Cataclysmic Variables
Daniel Proga
We review the main results from line-driven (LD) models of winds from accretion disks in cataclysmic variables (CVs). We consider LD disk wind models in the hydrodynamic (HD) and m…
Reverberation Mapping of the Broad Line Region: application to a hydrodynamical line-driven disk wind solution
Tim Waters, Amit Kashi, Daniel Proga +3
The latest analysis efforts in reverberation mapping are beginning to allow reconstruction of echo images (or velocity-delay maps) that encode information about the structure and k…
Multiphase AGN winds from X-ray irradiated disk atmospheres
Tim Waters, Daniel Proga, Randall Dannen
The mechanism of thermal driving for launching mass outflows is interconnected with classical thermal instability (TI). In a recent paper, we demonstrated that as a result of this…
The MHD collapsar model for GRBs: an inflow produces an outflow
Daniel Proga
We present our recent results from numerical simulations of a magnetized flow in the vicinity of a black hole in the context of the collapsar model for GRBs. The simulations show t…
AGN STORM 2. III. A NICER view of the variable X-ray obscurer in Mrk 817
Ethan R. Partington, Edward M. Cackett, Erin Kara +44
The AGN STORM 2 collaboration targeted the Seyfert 1 galaxy Mrk 817 for a year-long multiwavelength, coordinated reverberation mapping campaign including HST, Swift, XMM-Newton, NI…
Thermal Disk Winds in X-ray Binaries: Realistic Heating and Cooling Rates Give Rise to Slow, but Massive Outflows
Nick Higginbottom, Daniel Proga, Christian Knigge +1
A number of X-ray binaries exhibit clear evidence for the presence of disk winds in the high/soft state. A promising driving mechanism for these outflows is mass loss driven by the…
SPH Simulations of Black Hole Accretion: A Step to Model Black Hole Feedback in Galaxies
Paramita Barai, Daniel Proga, Kentaro Nagamine
(Abridged) We test how accurately the smoothed particle hydrodynamics (SPH) numerical technique can follow spherically-symmetric Bondi accretion. Using the 3D SPH code GADGET-3, we…
Non-Axisymmetric Line Driven Disc Winds II - Full Velocity Gradient
Sergei Dyda, Daniel Proga
We study non-axisymetric features of 3D line driven winds in the Sobolev approximation, where the optical depth is calculated using the full velocity gradient. We find that non-axi…
Momentum Driving: which physical processes dominate AGN feedback?
Jeremiah P. Ostriker, Ena Choi, Luca Ciotti +2
The deposition of mechanical feedback from a supermassive black hole (SMBH) in an active galactic nucleus (AGN) into the surrounding galaxy occurs via broad-line winds which must c…
The saturation mechanism of thermal instability
Tim Waters, Daniel Proga
The literature on thermal instability (TI) reveals that even for a simple homogeneous plasma, the nonlinear outcome ranges from a gentle reconfiguration of the initial state to an…
Variable X-ray absorption in the mini-BAL QSO PG 1126-041
Margherita Giustini, Massimo Cappi, George Chartas +7
X-ray studies of active galactic nuclei (AGN) with powerful nuclear winds are important for constraining the physics of the inner accretion/ejection flow around supermassive black…
Accretion of Low Angular Momentum Material onto Black Holes: Radiation Properties of Axisymmetric MHD Flows
Monika Moscibrodzka, Daniel Proga, Bozena Czerny +1
Numerical simulations of MHD accretion flows in the vicinity of a supermasssive black hole provide important insights to the problem of why and how systems -- such as the Galactic…
Low angular momentum accretion in the collapsar: how long can a long GRB be?
Agnieszka Janiuk, Daniel Proga
The collapsar model is the most promising scenario to explain the huge release of energy associated with long duration gamma-ray-bursts (GRBs). Within this scenario GRBs are believ…
On the wind-driven relaxation cycle in accretion disks
Shalini Ganguly, Daniel Proga
A disk wind can cause perturbations that propagate throughout the disk via diffusive processes. On reaching the inner disk, these perturbations can change the disk luminosity, whic…
Photoionization calculations of the radiation force due to spectral lines in AGNs
Randall C. Dannen, Daniel Proga, Timothy R. Kallman +1
One of the main mechanisms that could drive mass outflows in AGNs is radiation pressure due to spectral lines. Although straightforward to understand, the actual magnitude of the r…
On the large-scale outflows in active galactic nuclei: consequences of coupling the mass-supply rate and accretion luminosity
Ryuichi Kurosawa, Daniel Proga
(Abridged) We present two-dimensional hydrodynamical simulations of slowly rotating gas that is under the influence of the gravity of a super massive black hole and is irradiated b…
Time-Dependent AGN Disc Winds I -- X-ray Irradiation
Sergei Dyda, Shane W. Davis, Daniel Proga
We study AGN line driven disc winds using time-dependent radiation hydrodynamics. The key criterion for determining wind launching is the coupling strength of the UV radiation fiel…
Line-driven Disk Winds in Active Galactic Nuclei: The Critical Importance of Ionization and Radiative Transfer
Nick Higginbottom, Daniel Proga, Christian Knigge +3
Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGN) and quasi-stellar objects (QSOs). These outflows…
Outflows from inflows: the nature of Bondi-like accretion
Tim Waters, Aycin Aykutalp, Daniel Proga +3
The classic Bondi solution remains a common starting point both for studying black hole growth across cosmic time in cosmological simulations and for smaller scale simulations of A…
AGN STORM 2: IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-ray Spectroscopy
Fatima Zaidouni, Erin Kara, Peter Kosec +45
We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multi-wavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the…
On the diversity and complexity of absorption line profiles produced by outflows in Active Galactic Nuclei
Margherita Giustini, Daniel Proga
Understanding the origin of AGN absorption line profiles and their diversity could help to explain the physical structure of the accretion flow, and also to assess the impact of ac…
The physics and astrophysics of X-ray outflows from Active Galactic Nuclei
Sibasish Laha, Randall Smith, Panayiotis Tzanavaris +20
The highly energetic outflows from Active Galactic Nuclei detected in X-rays are one of the most powerful mechanisms by which the central supermassive black hole (SMBH) interacts w…
Radiation driven winds from luminous accretion disks
Daniel Proga, James M. Stone, Janet E. Drew
We study the 2-D, time-dependent hydrodynamics of radiation-driven winds from accretion disks in which the radiation force is mediated by spectral lines. If the dominant contributi…
Large-Scale Outflows from AGN: a link between central black holes and galaxies
Daniel Proga, Ryuichi Kurosawa, Kentaro Nagamine
We summarize the results from numerical simulations of mass outflows from AGN. We focus on simulations of outflows driven by radiation from large-scale inflows. We discuss the prop…
Parker Winds Revisited: An Extension to Disc Winds
Timothy R. Waters, Daniel Proga
A simple 1D dynamical model of thermally driven disc winds is proposed, based on the results of recent, 2.5D axi-symmetric simulations. Our formulation of the disc wind problem is…
Hubble Space Telescope Ultraviolet Spectroscopy of Fourteen Low-Redshift Quasars
Rajib Ganguly, Michael S. Brotherton, Nahum Arav +35
We present low-resolution ultraviolet spectra of 14 low redshift (z<0.8) quasars observed with HST/STIS as part of a Snap project to understand the relationship between quasar outf…
Dynamics of radiatively inefficient flows accreting onto radiatively efficient black hole objects
Daniel Proga
I present results from numerical simulations of gas dynamics outside luminous accretion disks in active galactic nuclei. The gas, gravitationally captured by a super massive black…
Time Dependent Radiation Driven Winds
Sergei Dyda, Daniel Proga
We study temporal variability of radiation driven winds using one dimensional, time dependent simulations and an extension of the classic theory of line driven winds developed by C…
A global view of the inner accretion and ejection flow around super massive black holes: radiation driven accretion disk winds in a physical context
Margherita Giustini, Daniel Proga
Understanding the physics and geometry of accretion and ejection around super massive black holes (SMBHs) is important to understand the evolution of active galactic nuclei (AGN) a…
AGN STORM 2. VI. Mapping Temperature Fluctuations in the Accretion Disk of Mrk 817
Jack M. M. Neustadt, Christopher S. Kochanek, John Montano +49
We fit the UV/optical lightcurves of the Seyfert 1 galaxy Mrk 817 to produce maps of the accretion disk temperature fluctuations resolved in time and radius. The maps a…
AGN STORM 2: II. Ultraviolet Observations of Mrk817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope
Y. Homayouni, Gisella De Rosa, Rachel Plesha +62
We present reverberation mapping measurements for the prominent ultraviolet broad emission lines of the active galactic nucleus Mrk817 using 165 spectra obtained with the Cosmic Or…
Chemical Abundances in AGN Environment: X-Ray/UV Campaign on the MRK 279 Outflow
Nahum Arav, Jack R. Gabel, Kirk T. Korista +11
We present the first reliable determination of chemical abundances in an AGN outflow. The abundances are extracted from the deep and simultaneous FUSE and HST/STIS observations of…
The black holes of radio galaxies during the "Quasar Era": Masses, accretion rates, and evolutionary stage
Nicole P. H. Nesvadba, Carlos De Breuck, Matt D. Lehnert +3
We present an analysis of the AGN broad-line regions of 6 powerful radio galaxies at z>~2 (HzRGs) with rest-frame optical imaging spectroscopy obtained at the VLT. All galaxies hav…
On how much X-ray and UV radiation processes are coupled in accretion disks: AGN case
Daniel Proga
Within the standard accretion disk theory for active galactic nuclei (AGN), the observed X-rays are often modeled by Compton up-scattering of ultraviolet (UV) disk photons inside a…
Theory of winds in AGNs
Daniel Proga
I present a brief review of theory of winds in active galactic nuclei (AGN). Magnetic, radiation, and thermal driving likely operate in AGN. In many cases, it is difficult to disti…
Comparison of theoretical radiation-driven winds from stars and discs
Daniel Proga
We compare models of line-driven winds from accretion discs and single spherical stars. We look at the problem of scaling mass-loss rates and velocities of stellar and disc winds w…
Thermal instability in radiation hydrodynamics: instability mechanisms, position-dependent S-curves, and attenuation curves
Daniel Proga, Tim Waters, Sergei Dyda +1
Local thermal instability can plausibly explain the formation of multiphase gas in many different astrophysical environments, but the theory is only well understood in the opticall…
On the transition from efficient to inefficient line-driving in irradiated flows
Randall Dannen, Daniel Proga, Tim Waters
Observations of ionized AGN outflows have provided compelling evidence that the radiation field transfers both momentum and energy to the plasma. At parsec scale distances in AGN,…
The Black Hole Candidate Swift J1728.93613 and the Supernova Remnant G351.90.9
Mayura Balakrishnan, Paul A. Draghis, Jon M. Miller +12
A number of neutron stars have been observed within the remnants of the core-collapse supernova explosions that created them. In contrast, black holes are not yet clearly associate…
On the Virialization of Disk Winds: Implications for the Black Hole Mass Estimates in AGN
Amit Kashi, Daniel Proga, Kentaro Nagamine +2
Estimating the mass of a supermassive black hole (SMBH) in an active galactic nucleus (AGN) usually relies on the assumption that the broad line region (BLR) is virialized. However…
On time variability and other complications in studying the UV broad absorption lines of quasars: results from numerical simulations of radiation driven disk winds
Daniel Proga, Paola RodrÃguez Hidalgo, Fred Hamann
We review the main results from axisymmetric, time-dependent hydrodynamical simulations of radiation driven disk winds in AGN. We illustrate the capability of such simulations to p…
On the duration of long GRBs: effects of black hole spin
Agnieszka Janiuk, Rafal Moderski, Daniel Proga
In the frame of the collapsar model for long gamma ray bursts (GRBs), we investigate the formation of a torus around a spinning BH and we check what rotational properties a progeni…
On the efficient acceleration of clouds in active galactic nuclei
Tim Waters, Daniel Proga
In the broad line region of AGN, acceleration occurs naturally when a cloud condenses out of the hot confining medium due to the increase in line opacity as the cloud cools. Howeve…
Time Evolution of the 3-D Accretion Flows: Effects of the Adiabatic Index and Outer Boundary Condition
Agnieszka Janiuk, Maciej Sznajder, Monika Moscibrodzka +1
We study a slightly rotating accretion flow onto a black hole, using the fully three dimensional (3-D)numerical simulations. We consider hydrodynamics of an inviscid flow, assuming…
Parker Winds Revisited: An Extension to Disk Winds
Tim Waters, Daniel Proga
A simple, one-dimensional dynamical model of thermally driven disk winds, one in the spirit of the original Parker (1958) model, is presented. We consider two different axi-symmetr…
Magnetized Accretion Flows: Effects of Gas Pressure
Monika Moscibrodzka, Daniel Proga
We study how axisymmetric magnetohydrodynamical (MHD) accretion flows depend on gamma adiabatic index in the polytropic equation of state. This work is an extension of Moscibrodzka…
Variable X-ray absorption in the mini-broad absorption line quasar PG 1126-041
Margherita Giustini, Massimo Cappi, George Chartas +7
We present the results of a multi-epoch observational campaign on the mini-broad absorption line quasar (mini-BAL QSO) PG 1126-041 performed with XMM-Newton from 2004 to 2009. Time…
AGN STORM 2. IV. Swift X-ray and ultraviolet/optical monitoring of Mrk 817
Edward M. Cackett, Jonathan Gelbord, Aaron J. Barth +48
The AGN STORM 2 campaign is a large, multiwavelength reverberation mapping project designed to trace out the structure of Mrk 817 from the inner accretion disk to the broad emissio…
Dynamics of Rotating Accretion Flows Irradiated by a Quasar
Daniel Proga, Jeremiah P. Ostriker, Ryuichi Kurosawa
We study the axisymmetric, time-dependent hydrodynamics of rotating flows that are under the influence of supermassive black hole gravity and radiation from an accretion disk surro…
Flux-Averaged Force Multipliers
Sergei Dyda, Randall C. Dannen, Shane W. Davis +2
We apply novel developments in photoionization modeling and multi-frequency radiation hydrodynamics to the study of line driven AGN disc winds. We use a flux-averaged force multipl…
Parsec-scale accretion and winds irradiated by a quasar
Anton Dorodnitsyn, Tim Kallman, Daniel Proga
We present numerical simulations of properties of a parsec-scale torus exposed to illumination by the central black hole in an active galaxy (AGN). Our physical model allows to inv…
Outflows from AGN: their Impact on Spectra and the Environment
Daniel Proga, Ryuichi Kurosawa
We present a brief summary of the main results from our multi-dimensional, time-dependent simulations of gas dynamics in AGN. We focus on two types of outflows powered by radiation…
Time variability of accretion flows: effects of the adiabatic index and gas temperature
Monika Moscibrodzka, Daniel Proga
We report on next phase of our study of rotating accretion flows onto black holes. We consider hydrodynamical (HD) accretion flows with a spherically symmetric density distribution…
On Synthetic Absorption Line Profiles of Thermally Driven Winds from Active Galactic Nuclei
Shalini Ganguly, Daniel Proga, Tim Waters +7
The warm absorbers observed in more than half of all nearby active galactic nuclei (AGN) are tracers of ionized outflows located at parsec scale distances from the central engine.…
Coronae and Winds from Irradiated Disks in X-ray binaries
Nick Higginbottom, Daniel Proga
X-ray and UV line emission in X-ray binaries can be accounted for by a hot corona. Such a corona forms through irradiation of the outer disk by radiation produced in the inner accr…
X-ray/UV Observing Campaign on the Mrk 279 AGN Outflow: A Global Fitting Analysis of the UV Absorption
Jack R. Gabel, Nahum Arav, Jelle S. Kaastra +12
We present an analysis of the intrinsic UV absorption in the Seyfert 1 galaxy Mrk 279 based on simultaneous long observations with the Hubble Space Telescope (41 ks) and the Far Ul…
Time-Dependent AGN Disc Winds II -- Effects of Photoionization
Sergei Dyda, Randall C. Dannen, Timothy R. Kallman +2
We use a combination of radiation hydrodynamics (rad-HD) and photoionization modeling to study line-driven disc winds for a range of black hole masses. We refined previous models b…
Cloud Formation and Acceleration in a Radiative Environment
Daniel Proga, Tim Waters
In a radiatively heated and cooled medium, the thermal instability is a plausible mechanism for forming clouds, while the radiation force provides a natural acceleration, especiall…
The Hot and Energetic Universe: A White Paper presenting the science theme motivating the Athena+ mission
Kirpal Nandra, Didier Barret, Xavier Barcons +237
This White Paper, submitted to the recent ESA call for science themes to define its future large missions, advocates the need for a transformational leap in our understanding of tw…
Illumination in symbiotic binary stars: Non-LTE photoionization models. II. Wind case
Daniel Proga, Scott J. Kenyon, John C. Raymond
We describe a non-LTE photoionization code to calculate the wind structure and emergent spectrum of a red giant wind illuminated by the hot component of a symbiotic binary system.…
Cloud coalescence: a dynamical instability affecting multiphase environments
Tim Waters, Daniel Proga
The mass and size distributions are the key characteristics of any astrophysical objects, including the densest clumps comprising the cold phase of multiphase environments. In our…
AGN STORM 2: VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations
Maryam Dehghanian, Nahum Arav, Gerard A. Kriss +39
We observed the Seyfert 1 galaxy Mrk817 during an intensive multi-wavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lin…
Gas Accretion onto a Supermassive Black Hole: a step to model AGN feedback
Kentaro Nagamine, Paramita Barai, Daniel Proga
We study the gas accretion onto a supermassive black hole (SMBH) using the 3D SPH code GADGET-3 on scales of 0.1-200 pc. First we test our code with spherically symmetric, adiabati…
Non-isobaric Thermal Instability
Tim Waters, Daniel Proga
Multiphase media have very complex structure and evolution. Accurate numerical simulations are necessary to make advances in our understanding of this rich physics. Because simulat…
Position dependent radiation fields near accretion disks
Kara Smith, Daniel Proga, Randall Dannen +2
In disk wind models for active galactic nuclei (AGN) outflows, high-energy radiation poses a significant problem wherein the gas can become overionized, effectively disabling what…
A radiation-driven disk wind model for massive young stellar objects
Janet E. Drew, Daniel Proga, James M. Stone
A radiation-driven disk wind model is proposed that offers great promise of explaining the extreme mass loss signatures of massive young stellar objects (the BN-type objects and mo…
Oscillatory Line-Driven Winds: The Role of Atmospheric Stratification
Joshua Key, Daniel Proga, Randall Dannen +2
Time-dependent numerical studies of line-driven winds using the Sobolev approximation have a history spanning over three decades. In many of these studies, the wind solutions displ…
Three-Dimensional Simulations of Inflows Irradiated by a Precessing Accretion Disk in Active Galactic Nuclei: Formation of Outflows
Ryuichi Kurosawa, Daniel Proga
We present three-dimensional (3-D) hydrodynamical simulations of gas flows in the vicinity of an active galactic nucleus (AGN) powered by a precessing accretion disk. We consider t…
Wind Acceleration as a Driver of Detached Blueshifted Absorption in Quasar Disk Winds
Randall C. Dannen, Daniel Proga, Paola RodrÃguez Hidalgo +4
Active galactic nuclei (AGN) unification models often emphasize the viewing angle, , but alone does not determine quasar properties. This is crucial for quasar outflows: UV…
Nonaxisymmetric Effects in the Black Hole Accretion Inviscid Hydrodynamics: Formation and Evolution of a Tilted Torus
Agnieszka Janiuk, Daniel Proga, Ryuichi Kurosawa
We report on the fourth phase of our study of slightly rotating accretion flows onto black holes. The main new element of this study is that we used fully three dimensional (3-D) n…
Linearly polarized X-ray flares following short gamma-ray bursts
Y. Z. Fan, Bing Zhang, Daniel Proga
Soft X-ray flares were detected to follow the short-duration gamma-ray burst GRB 050724. The temporal properties of the flares suggest that they are likely due to the late time act…
Ionized outflows from active galactic nuclei as the essential elements of feedback
Sibasish Laha, Christopher S. Reynolds, James Reeves +5
Outflows from active galactic nuclei (AGN) are one of the fundamental mechanisms by which the central supermassive black hole interacts with its host galaxy. Detected in …
Synthetic absorption lines for a clumpy medium: a spectral signature for cloud acceleration in AGN?
Tim Waters, Daniel Proga, Randall Dannen +1
There is increasing evidence that the highly ionized multiphase components of AGN disk winds may be due to thermal instability. The ions responsible for forming the observed X-ray…
Regulation of Black Hole Winds and Jets Across the Mass Scale
Ashley L. King, Jon M. Miller, John Raymond +7
We present a study of the mechanical power generated by both winds and jets across the black hole mass scale. We begin with the study of ionized X-ray winds and present a uniform a…
Dynamics of Accretion Flows Irradiated by a Quasar
Daniel Proga
We present the results from axisymmetric time-dependent HD calculations of gas flows which are under the influence of gravity of a black hole in quasars. We assume that the flows a…