Related papers: A Quasar Wind Model
High velocity outflows from supermassive black holes have been invoked to explain the recent identification of strong absorption features in the hard X-ray spectra of several quasars. Here, Monte Carlo radiative transfer calculations are…
I present a brief review about our ideas concerning the origin and nature of the broad line emitting gas. This is one of the outstanding problems in quasar research. I suggest the establishment of a central data base of high quality quasar…
Background quasars are potentially sensitive probes of galactic outflows provided that one can determine the origin of the absorbing material since both gaseous disks and strong bipolar outflows can contribute to the absorption…
The model I recently proposed for the structure of quasars offers to unify the many aspects of Type 1 AGN: emission lines, absorption lines and reflection features. This makes the model heavily overconstrained by observation and readily…
The quadruply lensed quasar HE0435-1223 shows a clear microlensing effect that affects differently the blue and red wings of the H$\alpha$ line profile in its image D. To interpret these observations, and constrain the broad emission line…
The emission-line spectrum of a quasar is most likely emitted by an ensemble of photoionized clouds moving with a variety of velocities, with a range of densities and distances from the central object. The state of the art in this field is…
The radio, optical, X-ray and gamma-ray nebulae that surround many pulsars are thought to arise from synchrotron and inverse Compton emission. The energy powering this emission, as well as the magnetic fields and relativistic particles, are…
Polytropic models of stellar winds remain to be useful tools because they allow for a simple description of the energy balance of the expanding plasma without explicitly specifying potentially complex energy transport processes like, e.g.,…
The Chevalier & Clegg (1985) spherical wind is widely used to model galactic outflows. Efforts are underway to understand the production of multiphase gas in such outflows. Since the important scales for the multiphase gas are very small…
The propagation speed of a circumstellar pattern revealed in the plane of the sky is often assumed to represent the expansion speed of the wind matter ejected from a post-main-sequence star at the center. We point out that the often-adopted…
A new model for the high-energy emission from pulsars is developed by considering charged particle motion in the fields of a spinning, highly magnetised and conducting sphere in vacuum. A generally applicable approximation to the particle…
Winds arising from galaxies, star clusters, and active galactic nuclei are crucial players in star and galaxy formation, but it has proven remarkably difficult to use observations of them to determine physical properties of interest,…
High velocity (HV) outflows are an important but poorly understood aspect of quasar/SMBH evolution. Outflows during the luminous accretion phase might play a critical role in "unveiling" young dusty AGN and regulating star formation in the…
The launch of high-spectral-resolution x-ray telescopes (Chandra, XMM) has provided a host of new spectral line diagnostics for the astrophysics community. In this paper we discuss Doppler-broadened emission line profiles from highly…
Most of the hadronic jet models for quasars (QSOs) and microquasars (MQs) found in literature represent beams of particles (e.g. protons). These particles interact with the matter in the stellar wind of the companion star in the system or…
Quasars show a remarkable degree of atomic emission line-broadening, an observational feature which, in conjunction with a radial distance estimate for this emission from the nucleus is often used to infer the mass of the central…
We test a scenario claiming that the broad absorption line (BAL) phenomenon in quasars (QSOs) is not a temporary stage of their life. In this scenario, we see the BAL effect only if the line of sight is within a spatially limited and…
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.…
Photospheric radiation momentum is efficiently transferred by absorption through metal lines to the gaseous matter in the atmospheres of massive stars, sustaining strong winds and mass loss rates. Not only is this critical for the evolution…
Much effort has been done in order to better understand the active galactic nuclei mechanisms behind the relativistic jets observed in radio-loud sources. These phenomena are commonly seen in luminous objects with intermediate/high redshift…