Related papers: Broad Line Region Physical Conditions along the Qu…
We report new spectroscopic observations performed in 2010 and 2011 for luminous radio-quite quasar PG 1416-129. Our new spectra with high quality cover both H$\beta$ and H$\alpha$ regions, and show negligible line profile variation within…
Weak emission-line quasars (WLQs) are a subset of Type 1 quasars that exhibit extremely weak Ly$\alpha +$N V $\lambda$1240 and/or C IV $\lambda$1549 emission lines. We investigate the relationship between emission-line properties and…
We present high S/N UV spectra for eight quasars at $z\sim3$\ obtained with VLT/FORS. The spectra enable us to analyze in detail the strongest emission features in the rest-frame range 1400-2000 \AA\ of each source (\ciii, \siiii, \aliii,…
We present a catalog of broad H$\beta$ variability properties for all spectra of quasars with $z<0.8$ and at least two observations included in the Sloan Digital Sky Survey (SDSS) Data Release 16 quasar catalog. For each spectrum, we…
We have compiled the emission-line fluxes of O I 8446, O I 11287, and the near-IR Ca II triplet (8579) observed in 11 quasars. These lines are considered to emerge from the same gas as do the Fe II lines in the low-ionized portion of the…
We study the differences in physical properties of quasar-host galaxies using an optically selected sample of radio loud (RL) and radio quiet (RQ) quasars (in the redshift range 0.15 < z < 1.9) which we have further cross-matched with the…
Different properties of quasars may be observed and analysed through the many ranges of the electromagnetic spectrum. Pioneering studies showed that an "H-R diagram" for quasars was needed to organize these data, and that more than two…
We present high S/N UV spectra for eight quasars at z $\sim$ 3 obtained with VLT/FORS. The spectra enable us to analyze in detail the strong and weak emission features in the rest-frame range 1300-2000 A of each source (Ciii]$\lambda$1909,…
We report the results of analysis of the Hbeta emission-line region of a sample of thirty low-redshift (z<1) iron low-ionization broad absorption line quasars (FeLoBALQs). Eleven of these objects are newly classified as FeLoBALQs. A matched…
We present results of the near-infrared (IR) spectroscopy of six quasars whose redshifts range from 0.158 to 1.084. Combined with the satellite ultraviolet data, the relative line strengths of OI 1304, OI 8446, OI 11287, and the near-IR…
The elemental abundances in the broad-line regions of high-redshift quasars trace the chemical evolution in the nuclear regions of massive galaxies in the early universe. In this work, we study metallicity-sensitive broad emission-line flux…
Using a sample of 30,000 quasars from SDSS-DR7, we explore the range of properties exhibited by high-ionization, broad emission lines, such as CIV 1549. Specifically we investigate the anti-correlation between L_UV and emission line EQW…
A combined analysis of the profiles of the main broad quasar emission lines in both Hubble Space Telescope and optical spectra shows that while the profiles of the strong UV lines are quite similar, there is frequently a strong increase in…
We present a high S/N spectrum for the quasar PG 1138+222. We detect a very broad HeII$\lambda$4686 emission line component with twice the FWHM of the conventional broad line region (BLR) as evidenced by the Balmer lines. The profile shape…
We studied the spectra of six $z \sim 2.2$ quasars obtained with the X-shooter spectrograph at the Very Large Telescope. The redshift of these sources and X-shooter's spectral coverage allow us to cover the rest spectral range $\sim1200 -…
We study the rest-frame optical properties of 74 luminous (L_bol=10^46.2-48.2 erg/s), 1.5<z<3.5 broad-line quasars with near-IR (JHK) slit spectroscopy. Systemic redshifts based on the peak of the [OIII]5007 line reveal that redshift…
We report on the results of a new spectroscopic monitoring campaign of the quasar PG 0026+129 at the Calar Alto Observatory 2.2m telescope from July 2017 to February 2020. Significant variations in the fluxes of the continuum and…
A quasar main sequence is widely believed to reveal itself through objects represented in a plane spanned by two parameters: the full-width at half-maximum (FWHM) of H$\beta{}$, and the ratio of Fe II to H$\beta{}$ equivalent width. This…
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…
Surveys have shown radio-loud (RL) quasars constitute 10%-15% of the total quasar population and rest are radio-quiet (RQ). However, it is unknown if this radio-loud fraction (RLF) remains consistent among different parameter spaces. This…