Related papers: Continuum and Emission Line Strength Relations for…
We used a large, homogeneous sample of 4178 z <= 0.8 Seyfert 1 galaxies and QSOs selected from the Sloan Digital Sky Survey to investigate the strength of Fe II emission and its correlation with other emission lines and physical parameters…
We present the results of an investigation on the main structural properties derived from VRI and Halpha surface photometry of galaxies hosting nuclear emission-line regions (including Seyfert 1, Seyfert 2, LINER and starburst galaxies) as…
This is the second in a series of papers aiming to test how the mass ($M_{\rm BH}$), accretion rate ($\dot{M}$) and spin ($a_{*}$) of super massive black holes (SMBHs) determine the observed properties of type-I active galactic nuclei…
We use extensive spectroscopy from the MOSFIRE Deep Evolution Field (MOSDEF) survey to investigate the relationships between rest-frame optical emission line equivalent widths ($W$) and a number of galaxy and ISM characteristics for a…
The nature of weak emission-line quasars (WLQs) is probed by comparing the Baldwin effect (BEff) in WLQs and normal quasars (QSOs). We selected 81 high-redshift (z>2.2) and 2 intermediate-redshift (z=1.66 and 1.89) WLQs. Their rest-frame…
The width of the broad H-beta emission line is the primary defining characteristic of the NLS1 class. This parameter is also an important component of Boroson and Green's optical Eigenvector 1 (EV1), which links steeper soft X-ray spectra…
We have analyzed new and archival IUE observations of narrow-line Seyfert 1 galaxies (NLS1) in order to revise the ultraviolet (UV) properties of this sub-group of Active Galactic Nuclei (AGN). We have found broad wings in the strongest UV…
We present deep HST near-IR and Spitzer mid-IR observations of a large sample of spectroscopically-confirmed galaxies at z >= 6. The sample consists of 51 Lyman-alpha emitters (LAEs) at z ~ 5.7, 6.5, and 7.0, and 16 Lyman-break galaxies…
We assemble a sample consisting of 66 active galactic nuclei (AGNs) from literature and the {\em XMM-Newton} archive in order to investigate the origin of the 6.4 keV narrow iron K$\alpha$ line (NIKAL). The X-ray Baldwin effect of the NIKAL…
A strong X-ray outburst was detected in HE1136-2304 in 2014. Accompanying optical spectra revealed that the spectral type has changed from a nearly Seyfert 2 type (1.95), classified by spectra taken 10 and 20 years ago, to a Seyfert 1.5 in…
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…
We present the results of an optical spectroscopic survey designed to search for low-luminosity, "dwarf" Seyfert nuclei in a magnitude-limited sample of 486 bright, northern galaxies. Moderate-resolution spectra of exceptionally high…
We present modeling and interpretation of the continuum and emission lines for a sample of 51 unobscured Type 1 active galactic nuclei (AGN). All of these AGNs have high quality spectra from both XMM-Newton and Sloan Digital Sky Survey…
We present new results for a sample of 33 narrow-lined UV-selected active galactic nuclei (AGNs), identified in the course of a spectroscopic survey for star-forming galaxies at z ~ 2-3. The rest-frame UV composite spectrum for our AGN…
In a single optical spectrum, the quasar narrow-line region (NLR) reveals low density, photoionized gas in the host galaxy interstellar medium, while the immediate vicinity of the central engine generates the accretion disk continuum and…
Weak-line quasars (WLQs) are a subset of type 1 quasars with remarkably weak high-ionization broad emission lines but normal optical/UV continua. Using 371,091 quasars from SDSS DR16, we define WLQs by analyzing outliers in three relations:…
Narrow line Seyfert 1 (NLSy1) galaxies constitute a class of active galactic nuclei characterized by the full width at half maximum (FWHM) of the H$\beta$ broad emission line < 2000 km/s and the flux ratio of [O III] to H$\beta$ < 3. Their…
We selected 27244 nearby, red, giant early-type galaxies (RGEs) from the Sloan Digital Sky Survey (SDSS). In a large fraction (53%) of their spectra the [O III] emission line is detected, with an equivalent width (EW) distribution strongly…
We performed an optical spectroscopic monitoring of the blazar 3C 454.3 from September 2003 to July 2008. Sixteen optical spectra were obtained during different runs, which constitute the first spectroscopic monitoring done in the…
We present the results from a 3-year-long Ultraviolet monitoring campaign of the broad line Seyfert 1 galaxy ESO 141-G55 using International Ultraviolet Explorer (IUE). By modelling all individual, extinction-corrected UV spectra in…