We consider the effect of radiation pressure from ionizing photons on black hole (BH) mass estimates based application virial theorem to broad emission lines in AGN spectra. BH masses only product Δ V2R and neglecting can be severely underestimated, especially objects close Eddington limit. provide an empirical calibration correction for pressure, we show that it is consistent with a simple physical model which BLR clouds are optically thick have average column densities NH ∼ 1023 cm −2....

We present a new analysis of 9-d long XMM–Newton monitoring the narrow-line Seyfert 1 galaxy Mrk 766. show that strong changes in spectral shape, which occurred during this observation, can be interpreted as due to broad-line region clouds crossing line sight X-ray source. Within occultation scenario, and temporal analyses eclipses provide precise estimates geometrical structure, location physical properties absorbing clouds. In particular, we these have cores with column densities at least...

We use a long (300 ksec), continuous Suzaku X-ray observation of the active nucleus in NGC1365 to investigate structure circumnuclear BLR clouds through their occultation source. The variations absorbing column density and covering factor indicate that surrounding black hole are far from having spherical geometry (as sometimes assumed), instead they have strongly elongated cometary shape, with dense head (n=10^11 cm^-3) an expanding, dissolving tail. infer tails must be longer than few times...

The application of the virial theorem to Broad Line Region Active Galactic Nuclei allows Black Hole mass estimates for large samples objects at all redshifts. In a recent paper we showed that ionizing radiation pressure onto BLR clouds affects BH and provided empirically calibrated corrections. More recently, new test importance forces has been proposed: MBH-sigma relation used estimate MBH sample type-2 AGN relations (with without pressure) type-1 extracted from same parent population....

Recent time-resolved spectral studies of a few Active Galactic Nuclei in hard X-rays revealed occultations the X-ray primary source probably by Broad Line Region (BLR) clouds. An important open question on structure circumnuclear medium AGN is whether this phenomenon common, i.e. significant fraction absorption due to BLR Here we present first attempt perform kind analysis homogeneous way, statistically representative sample AGN, consisting ~40 brightest sources with long XMM-Newton and/or...

view Abstract Citations (46) References (51) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Inverse Compton Thermostat in Hot Plasmas near Accreting Black Holes Pietrini, Paola ; Krolik, Julian H. X-ray spectra of accreting black hole systems generally contain components (sometimes dominating the total emission) which are well fitted by thermal Comptonization models with temperatures ∼100 keV. We demonstrate why, over many orders magnitude heating rate...

Context.Recent studies of the X-ray spectrum quasar 3C 273, analyzing both BeppoSAX data and XMM-Newton data, have shown that, depending on state source, Seyfert-like spectral features, including a significant soft excess, can be detected superimposed generally overwhelming beamed non-thermal emission ("jet" component).

Accretion disk coronae are believed to account for X-ray emission in Active Galactic Nuclei (AGNs). In this paper the observed is assumed be due a population of relativistic, non-thermal electrons (e.g. produced flare) injected at top an accretion magnetic loop. While stream along field lines, their energy distribution evolves time essentially because inverse Compton and synchrotron losses. The corresponding time-dependent due, range, mechanism, has been computed. Since typical decay flare...

[1] We present a new approach to the study of two-fluid hydrodynamics weakly collisional plasma systems, such as those frequently encountered in astrophysical context. Our starting point is novel procedure developed past years by Chen, Rao, and Spiegel (CRS) for fluid description semicollisional neutral monoatomic gases. The system equations that include viscous conductive effects has been successfully tested. However, extension plasmas not straightforward one. have deal with (at least) two...

In recent years the short-time X-ray variability of AGNs has been interpreted in terms varying absorption from temporary occultation primary source itself owing to passage absorbing clouds. Detailed analyses have shown that these clouds are located same region and physical properties similar those broad line (BLR) emitting The aim this paper is investigate detail whether group orbiting can account for BLR cloud eclipsing as well. To purpose we looked a distribution size number density...

view Abstract Citations (11) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Extragalactic Jets as Current-carrying Systems. I. Equilibrium and Stability Chiuderi, Claudio ; Pietrini, Paola Ciamponi, Guidetta Torricelli We present a model for extragalactic jets considered magnetized current-carrying structures. Unlike previous models the return currents are assumed to flow within jet itself. Standard MHD equations in cylindrical geometry used...

A normal-mode stability analysis is performed on a set of stationary equilibrium configurations, originally introduced by Chiuderi, Pietrini, and Torricelli-Ciamponi (Astrophys. J., in press) to describe the structure extragalactic jets. The examined equilibria are characterized three parameters that allow magnetic field configuration magnitude flow speed be changed. Moreover, two different cases for velocity considered, namely v0∥B0, purely longitudinal v0. Thus instability properties wide...

The application of the virial theorem provides a tool to estimate supermassive black hole (BH) masses in large samples active galactic nuclei (AGN) with broad emission lines at all redshifts and luminosities, if line region (BLR) is gravitationally bound. In this paper we discuss importance radiation forces on BLR clouds arising from deposition momentum by ionizing photons. Such counteract gravitational ones and, not taken into account, BH can be severely underestimated. We provide relations...

A sample of quasars has been recently assembled to investigate the non-linear relation between their monochromatic luminosities at 2500 Å and 2 keV exploit as a new class ‘standardized candles’. The use this technique for cosmological purposes relies on non-evolution with redshift UV-optical spectral properties quasars, well absence possible contaminants such dust extinction host galaxy contribution. We address these issues by analysing our quasar sample. produced composite spectra in...

Context. Short-term X-ray variability in active galactic nuclei (AGNs) can be explained as being due to varying absorption induced by the temporary occultation of primary source, when moving absorbing clouds cross line sight source itself. Earlier work suggests that these have physical properties similar those broad-line region (BLR) emitting and are located same spatial region. Aims. We intend extract information on each individual absorber associated with any given event detected our...

We study radiation hydrodynamical normal modes of radiation-supported accretion disks in the WKB limit. It has long been known that large optical depth limit standard equilibrium is unstable to convection. how growth rate depends on location within disk, depth, disk rotation, and way which local dissipation density pressure. The greatest rates are found near surface. Rotation stabilizes vertical wavevectors, so growing tend have nearly horizontal wavevectors. Over likely range depths, linear...

view Abstract Citations (10) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Comptonization Effects as a Test for Hot Intercloud Medium in the Broad-Line Region of Active Galactic Nuclei Ferrara, A. ; Pietrini, P. In framework standard model BLR, we tackle problem testing existence hot intercloud medium, required BLR cloud confinement. This is accomplished by analyzing possible effects on broad-line profiles, specifically Lyα and Hα...

view Abstract Citations (8) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Extragalactic Jets as Current-carrying Systems. III. Energy Requirements and Critical Discussion Torricelli-Ciamponi, Guidetta ; Pietrini, Paola In this paper the equilibrium model developed in first of series, by Chiuderi, to describe extragalactic jets is critically reviewed. particular, two aspects have been analyzed compared with observational constraints: global...

In Active Galactic Nuclei (AGNs) the presence of a star cluster around central black hole can have several effects on dynamics and emission global system. this paper we analyze interaction stellar atmospheres with wind outflowing from region AGN nucleus. Even small mass loss stars, as well possible collisions, give non-negligible contribution in feeding matter into nuclear wind. Moreover, produce envelopes surrounding stars that turn out to be suitable for reproducing observed Broad Line...

view Abstract Citations (1) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Magnetohydrodynamic Models for Extragalactic Jets. II. Multistep Structures Torricelli-Ciamponi, Guidetta ; Pietrini, Paola This paper presents a generalization of the method introduced in Pietrini & Torricelli-Ciamponi to model evolution along z jetlike axisymmetric structures. In above mentioned paper, conservation laws flow mass, magnetic field, momentum, and energy...

view Abstract Citations (2) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Magnetohydrodynamic Models for Extragalactic Jets. I. General Method Based on Conservation Laws Pietrini, Paola ; Torricelli-Ciamponi, Guidetta Recently an attempt has been made to model large-scale extragalactic jets as cylindrically symmetric flows of thermal matter, endowed with magnetic fields consistently generated by a system currents flowing within the jet. The...

Chiuderi et al. (2011) (paper 1) investigated the possibility of extending to weakly collisional plasmas new fluid scheme recently developed by Chen (2000) for neutral gases. Paper 1 established conditions under which such an extension is feasible and identified solar wind as a good candidate test theory. Such performed in present paper, where we actually build model fast compare it with available data. We define basic assumptions adopted: steadiness, spherical symmetry, neglect magnetic...