Related papers: What's Emitting the Broad Emission Lines?
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 spectrum emitted by the Broad Emission Line Regions of Active Galactic Nuclei can measure the luminosity of the central object and the chemical composition of the interstellar medium in a very young galaxy, and so constrain the…
The last few years have seen the confirmation of several trends associated with the quasar main sequence. The idea of a main sequence for quasars is relatively recent, and its full potential for the observational classification and…
A quasar wind model is proposed to describe the spatial and velocity structure of the broad line region. This model requires detailed photoionization and magnetohydrodynamic simulation, as the broad line region it too small for direct…
Radio emission is a good indicator of the jet power of radio-loud quasars, while the emission in broad-line can well represent the accretion disc radiation in quasars. We compile a sample of all sources of which the broad-line fluxes are…
Broad lines in active galaxies are primarily emitted by photoionization processes that are driven by the incident continuum arising from a complex geometrical structure circumscribing the supermassive black hole. A model of the broad-band…
Further investigation of data on quasars, especially in the ultraviolet band, yields an amazingly coherent narrative which we present in this paper. Quasars are characterised by strong continuum emission and redshifted emission and…
"Diffuse" gamma rays consist of several components: truly diffuse emission from the interstellar medium, the extragalactic background, whose origin is not firmly established yet, and the contribution from unresolved and faint Galactic point…
We present measurements of the optical/UV emission lines for a large homogeneous sample of 993 quasars from the Large Bright Quasar Survey. Our largely automated technique accounts for continuum breaks and galactic reddening, and we perform…
Recent models for the emission clouds within the Broad Line Region of quasars suggest that they are due to transient overdensities within an overall turbulent medium. If this were the case, the broad line emission would spatially appear…
We explore the relationship between the extended radio and line emission for a radio-loud quasar sample including both core-dominated and lobe-dominated quasars. A strong correlation is present between the extended radio and broad-line…
After a short review of the quasar problem and what we can hope to learn from their emission line spectra, I discuss the current body of knowledge concerning quasar emission lines and their relationships to the local and ionizing continua.…
The physical nature of the material responsible for the high--velocity, broad-absorption line features seen in a small fraction of quasar spectra has been the subject of debate since their discovery. This has been especially compounded by…
We present graphically the results of several thousand photoionization calculations of broad emission line clouds in quasars, spanning seven orders of magnitude in hydrogen ionizing flux and particle density. The equivalent widths of 42…
We present evidence that the high-velocity CIV lambda 1549 emission line gas of radio-loud quasars may originate in a disk-like configuration, in close proximity to the accretion disk often assumed to emit the low-ionization lines. For a…
The similarity of quasar line spectra has been taken as an indication that the emission line clouds have preferred parameters, suggesting that the environment is subject to a fine tuning process. We show here that the observed spectrum is a…
This chapter is intended to provide a general presentation of the atomic and nuclear processes responsible for X-ray line and gamma-ray line emission in various astrophysical environments. I consider line production from hot plasmas, from…
The preliminary results from a deep emission-line search for warm ionized material in the halos of nearby active and star-forming galaxies are presented. The origin of this gas is discussed in the context of galaxy formation and evolution.
Energetic outflows appear to occur in conjunction with active mass accretion onto supermassive black holes. These outflows are most readily observed in the approximately 10% of quasars with broad absorption lines, where the observer's line…
Cosmic-ray interactions with interstellar gas and photons produce diffuse gamma-ray emission. In this talk we will review the current understanding of this diffuse emission and its relationship to the problem of the origin of cosmic rays.…