Related papers: The Intermediate Line Region and the Baldwin Effec…
Quasar emission lines are sensitive to both the luminosity and shape of the quasars' high energy continuum - primarily in the soft X-ray and the (obscured) extreme ultraviolet. We initiate the first large-scale, multi-line investigation of…
Aims. This study investigates the relationship between the Mg II {\lambda}2798 {\AA} emission line and the 3000 {\AA} continuum luminosity, as well as the Baldwin Effect, in a sample of 40,685 radio-quiet (RQ) quasars and 441 Flat Spectrum…
The origin of the luminosity dependence of the strength of broad and narrow emission lines in AGN (i.e. the Baldwin effect) is not firmly established yet. We explore this question using the Boroson & Green sample of the 87 z<=0.5 PG…
Using a realistic model for line emission from the broad emission line regions of quasars, we are able to reproduce the previously observed correlations of emission-line ratios with the shape of the spectral energy distribution (SED). In…
From a large homogeneous sample of optical/UV emission line measurements for 993 quasars from the Large Bright Quasar Survey (LBQS), we study correlations between emission line equivalent width and both restframe ultraviolet luminosity…
We divide a sample of 302 type-1 AGNs into two subsamples based on the narrow line [OIII]/Hbeta_{NLR} ratio, since we expect that there will be a stronger starburst (HII region) contribution to the narrow line emission for…
The anti-correlations between the equivalent widths of emission lines and the continuum luminosity in AGNs, known as the Baldwin effect are well established for broad lines, but are less well studied for narrow lines. In this paper we…
We report on the analysis of a large sample of 744 type 1 Active Galactic Nuclei, including quasars and Seyfert 1 galaxies across the redshift range from 0 < z < 5 and spanning nearly 6 orders of magnitude in continuum luminosity. We…
IZw1 is the prototype narrow line quasar. This type of AGNs show a number of common peculiar characteristics whose physical origin is not yet well understood. Here, I review the results of a detailed study by Laor et al. (1997b) of the UV…
We present our discovery of a narrow-line Baldwin effect, an anti-correlation between the equivalent width (EW) of a line and the flux of the associated continuum, in 5-20$\mu$m mid-infared lines from a sample of 68 Active Galactic Nuclei…
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.…
We present a study of optical Fe II emission in 302 AGNs selected from the SDSS. We group the strongest Fe II multiplets into three groups according to the lower term of the transition (b $^4$F, a $^6$S and a $^4$G terms). These correspond…
It is known that the blazar jet emissions are dominated by non-thermal radiation while the accretion disk jets are normally dominated by thermal emission. In this work, our aim is to study the connection between the two types of emission by…
We examine the variability of the high-ionizaton C IV line in a sample of 105 quasars observed at multiple epochs by the Sloan Digital Sky Survey. We find a strong correlation between the change in the C IV line flux and the change in the…
In a sample of 60 quasars selected from Sloan Digital Sky Survey (SDSS) with at least six-epoch spectroscopy, we investigate the variability of emission lines and continuum luminosity at various aspects. A strong anti-correlation between…
Using a sample of 30,000 quasars from SDSS-DR7, we explore the range of properties exhibited by high-ionization, broad emission lines, such as CIV 1549. Specifically we investigate the anti-correlation between L_UV and emission line EQW…
The UV to soft X-rays of luminous AGNs dominate their bolometric luminosity, driven by an accretion-powered dynamo at the center. These photons ionize the surrounding gas, thereby providing clues to fueling and exhaust. Two sets of…
We present the discovery of a Baldwin effect in 8 nearby Seyfert galaxies for the three most prominent mid-infrared forbidden emission lines observable from the ground that are commonly found in AGN, [ArIII](8.99 micron), [SIV](10.51…
Using a large sample of quasar spectra from the SDSS, we examine the composite spectral trends of quasars as functions of both redshift and luminosity, independently of one another. Aside from the well known Baldwin effect (BE) -- the…
We present measurements and statistical properties of the optical and ultraviolet emission lines present in the spectra of 85 bright quasars which have detailed spectral energy distributions. This heterogeneous sample has redshifts up to…