scholarly journals The size of the X-ray emitting region in SWIFT J2127.4+5654 via a broad line region cloud X-ray eclipse

2013 ◽  
Vol 436 (2) ◽  
pp. 1588-1594 ◽  
Author(s):  
M. Sanfrutos ◽  
G. Miniutti ◽  
B. Agís-González ◽  
A. C. Fabian ◽  
J. M. Miller ◽  
...  
Keyword(s):  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region

scholarly journals X-Ray Structure between the Innermost Disk and Optical Broad-line Region in NGC 4151

2018 ◽  
Vol 865 (2) ◽  
pp. 97 ◽  
Author(s):  
J. M. Miller ◽  
E. Cackett ◽  
A. Zoghbi ◽  
D. Barret ◽  
E. Behar ◽  
...  
Keyword(s):  
Broad Line ◽  
X Ray ◽  
Ngc 4151 ◽  
Broad Line Region ◽  
Line Region

scholarly journals Physical inference from the γ-ray, X-ray, and optical time variability of a large sample of Fermi blazars

2019 ◽  
Vol 490 (1) ◽  
pp. 124-134
Author(s):  
Anwesh Majumder ◽  
Kaustav Mitra ◽  
Ritaban Chatterjee ◽  
C M Urry ◽  
C D Bailyn ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cross Correlation ◽  
Time Lag ◽  
Monitoring Program ◽  
Emission Region ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region ◽  
Γ Ray

ABSTRACT We present cross-correlation studies of γ-ray (0.1–300 GeV), X-ray (0.2–10 keV), and optical (R band) variability of a sample of 26 blazars during 2008–2016. The light curves are from Fermi-LAT, Swift-XRT, and the Yale-SMARTS blazar monitoring program. We stack the discrete cross-correlation functions of the blazars such that the features that are consistently present in a large fraction of the sample become more prominent in the final result. We repeat the same analysis for two subgroups, namely, low synchrotron peaked (LSP) and high synchrotron peaked (HSP) blazars. We find that, on average, the variability at multiple bands is correlated, with a time lag consistent with zero in both subgroups. We describe this correlation with a leptonic model of non-thermal emission from blazar jets. By comparing the model results with those from the actual data, we find that the inter-band cross-correlations are consistent with an emission region of size 0.1 pc within the broad-line region for LSP blazars. We rule out large changes of magnetic field (>0.5 Gauss) across the emission region or small values of magnetic field (e.g., 0.2 Gauss) for this population. We also find that the observed variability of the HSP blazars can be explained if the emission region is much larger than the distance to the broad-line region from the central black hole.

scholarly journals The role of failed accretion disk winds in active galactic nuclei

2019 ◽  
Vol 15 (S356) ◽  
pp. 82-86 ◽  
Author(s):  
Margherita Giustini ◽  
Daniel Proga
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region ◽  
Gravitational Pull ◽  
Theoretical Evidence

AbstractBoth observational and theoretical evidence point at outflows originating from accretion disks as fundamental ingredients of active galactic nuclei (AGN). These outflows can have more than one component, for example an unbound supersonic wind and a failed wind (FW). The latter is a prediction of the simulations of radiation-driven disk outflows which show that the former is accompanied by an inner failed component, where the flow struggles to escape from the strong gravitational pull of the supermassive black hole. This FW component could provide a physical framework to interpret various phenomenological components of AGN. Here we briefly discuss a few of them: the broad line region, the X-ray obscurer, and the X-ray corona.

scholarly journals Stratified disc wind models for the AGN broad-line region: ultraviolet, optical, and X-ray properties

2020 ◽  
Vol 492 (4) ◽  
pp. 5540-5560 ◽  
Author(s):  
James H Matthews ◽  
Christian Knigge ◽  
Nick Higginbottom ◽  
Knox S Long ◽  
Stuart A Sim ◽  
...  
Keyword(s):  
Large Scale ◽  
Cloud Model ◽  
Line Emission ◽  
Spherical Geometry ◽  
Broad Line ◽  
Ionization State ◽  
X Ray ◽  
Broad Line Region ◽  
Smooth Flow ◽  
Line Region

ABSTRACT The origin, geometry, and kinematics of the broad-line region (BLR) gas in quasars and active galactic nuclei (AGN) are uncertain. We demonstrate that clumpy biconical disc winds illuminated by an AGN continuum can produce BLR-like spectra. We first use a simple toy model to illustrate that disc winds make quite good BLR candidates, because they are self-shielded flows and can cover a large portion of the ionizing flux-density (ϕH-nH) plane. We then conduct Monte Carlo radiative transfer and photoionization calculations, which fully account for self-shielding and multiple scattering in a non-spherical geometry. The emergent model spectra show broad emission lines with equivalent widths and line ratios comparable to those observed in AGN, provided that the wind has a volume filling factor of fV ≲ 0.1. Similar emission line spectra are produced for a variety of wind geometries (polar or equatorial) and for launch radii that differ by an order of magnitude. The line emission arises almost exclusively from plasma travelling below the escape velocity, implying that ‘failed winds’ are important BLR candidates. The behaviour of a line-emitting wind (and possibly any ‘smooth flow’ BLR model) is similar to that of the locally optimally emitting cloud model originally proposed by Baldwin et al. (1995), except that the gradients in ionization state and temperature are large-scale and continuous, rather than within or between distinct clouds. Our models also produce UV absorption lines and X-ray absorption features, and the stratified ionization structure can partially explain the different classes of broad absorption line quasars.

scholarly journals The dynamics of the broad-line region in NGC 3227

2020 ◽  
Vol 500 (1) ◽  
pp. 786-794
Author(s):  
Nick Devereux
Keyword(s):  
Emission Line ◽  
Hubble Space Telescope ◽  
Outer Radius ◽  
Short Time Scale ◽  
Broad Line ◽  
Fall Velocity ◽  
Space Telescope ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region

ABSTRACT Archival Hubble Space Telescope (HST) observations of the Seyfert 1 nucleus of NGC 3227 obtained with the Space Telescope Imaging Spectrograph (STIS) are re-examined in order to constrain a viable photoionization model for the broad-line region (BLR). The results imply that the BLR is a partially ionized, dust-free, spherical shell that is collapsing, supersonically, at the free-fall velocity due to its proximity to a supermassive black hole. The BLR is ionization bounded at the outer radius, coincident with the dust reverberation radius, and transforms into an X-ray emitting plasma inside the Balmer reverberation radius as the central UV–X-ray source is approached. Only 40 M⊙ of Hydrogen are required to explain the Balmer emission-line luminosity, but it is compressed by gravity into a column measuring 5.5 × 1024 atoms cm−2. Assuming radiatively inefficient accretion, the X-ray luminosity requires ∼10−2 M⊙ yr−1. However, the mass inflow rate required to explain the luminosity of the broad H α emission line is ∼1 M⊙ yr−1. The very large disparity between these two estimates indicates that 99 per cent of the inflowing gas must be re-directed into an outflow, and on a very short time-scale corresponding to ∼40 yr. Alternatively, the radiative efficiency of the inflow has been overestimated, or the X-ray luminosity has been underestimated, a distinct possibility if the BLR is indeed Compton-thick.

scholarly journals A Possible Mechanism to Explain the Narrow Line Variability of Seyfert Galaxies on Timescales of Months

1987 ◽  
Vol 121 ◽  
pp. 223-226
Author(s):  
Nikolay G. Bochkarev
Keyword(s):  
Phase Transfer ◽  
Seyfert Galaxies ◽  
Broad Line ◽  
Line Flux ◽  
Gas Emission ◽  
X Ray ◽  
Line Intensities ◽  
Broad Line Region ◽  
Line Region ◽  
Narrow Emission

Gas in the shadow of clouds in the outer parts of the broad line region can radiate a considerable fraction (dozens of percent) of the narrow emission line flux. The variability of the X-ray luminosity of the central source should result in significant variations of the gas emission on a timescale of months. Particularly strong changes of line intensities and column densities of gas in the shadow (~ 1023 cm−2) can be produced by phase transfer between two thermally stable fluids with temperatures 10–20×103 K and 40–100×103 K, which can exist in the shadow of clouds.

X-ray observations of IRAS selected Seyfert galaxies and obscuration of the broad-line region

1988 ◽  
Vol 324 ◽  
pp. 767 ◽  
Author(s):  
M. J. Ward ◽  
C. Done ◽  
A. C. Fabian ◽  
A. F. Tennant ◽  
R. A. Shafer
Keyword(s):  
Seyfert Galaxies ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region

scholarly journals Ubiquitous Column Density Variability in Seyfert 2 Galaxies

2002 ◽  
Vol 19 (1) ◽  
pp. 155-157 ◽  
Author(s):  
G. Risaliti ◽  
M. Elvis ◽  
F. Nicastro
Keyword(s):  
Column Density ◽  
Seyfert Galaxies ◽  
Broad Line ◽  
X Ray ◽  
Preliminary Results ◽  
Broad Line Region ◽  
Line Region ◽  
Standard Scenario ◽  
Region Scale ◽  
Almost All

AbstractWe present a study of X-ray column density variability in Seyfert 2 galaxies. We show that variations in NH are observed in almost all the objects with multiple hard X-ray observations. Variation timescales (as short as a few months in several cases) are not in agreement with the standard scenario of a parsec-scale toroidal absorber. We propose that the X-ray absorber in Seyfert galaxies is located much nearer to the centre than previously assumed, on the broad line region scale. An extension of the model by M. Elvis (2000) can explain the observed variability. We also show preliminary results of NH variability search inside single X-ray observations, which suggest that variations can occur on timescales of a few 104 s.

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