The FeII/MgII line flux ratio has been used to investigate the chemical evolution of high redshift active galactic nuclei (AGNs). No strong evolution has been found out to z~6, implying that the type 1a supernova activity has been already occurred in early universe. However, the trend of no evolution can be caused by the sample selection bias since the previous studies have utilized mostly very luminous AGNs, which may be already chemically matured at the observed redshift. As motivated by the previously reported correlation between AGN luminosity and metallicity, we investigate the FeII/MgII flux ratio over a large dynamic range of luminosity, by adding a new sample of 12 quasars at z~3, of which the lower luminosity limit is more than 1 dex smaller than that of the previously studied high-z quasars. Based on the Gemini/GNIRS observations, we find that the seven low-luminosity quasars with a mean bolometric luminosity log L_bol~46.5 \pm 0.2 has an average FeII/MgII ratio of 0.68 \pm 0.11 dex. This ratio is comparable to that of high-luminosity quasars (log L_bol~47.3 \pm 0.3) in our sample (i.e., FeII/MgII ratio of 0.59 \pm 0.15 dex) and that of the previously studied high-luminosity quasars at higher redshifts. One possible scenario is that the low-luminosity quasars in our sample are still relatively luminous and already chemically matured. To search for chemically-young AGNs, and fully understand the chemical evolution based on the FeII/MgII flux ratio, it is required to investigate much lower-luminosity AGNs.
We present the results of the reverberation monitoring aimed at MgII broad line and FeII pseudocontinuum for the luminous quasar CTS C30.10 (z = 0.90052) with the Southern African Large Telescope covering the years 2012-2021. We aimed at disentangling the MgII and UV FeII variability and the first measurement of UV FeII time delay for a distant quasar. We used several methods for time-delay measurements and determined both FeII and MgII time delays as well as performed a wavelength-resolved time delay study for a combination of MgII and FeII in the 2700 - 2900 Årestframe wavelength range. We o…
Non-resonant FeII* 2365, 2396, 2612, 2626 emission can potentially trace galactic winds in emission and provide useful constraints to wind models. From the 3'x3' mosaic of the Hubble Ultra Deep Field (UDF) obtained with the VLT/MUSE integral field spectrograph, we identify a statistical sample of 40 FeII* emitters and 50 MgII 2796, 2803 emitters from a sample of 271 [OII] 3726, 3729 emitters with reliable redshifts from z = 0.85 - 1.5 down to 2E-18 (3 sigma) ergs/s/cm^2 (for [OII]), covering the stellar mass range 10^8 - 10^11 Msun. The FeII* and MgII emitters follow the galaxy main sequence, …
The FeII/MgII line flux ratio has been used as an indicator of the Fe/Mg abundance ratio in the broad line region (BLR) of active galactic nuclei (AGNs). On the basis of archival rest-frame UV spectra obtained via the Hubble Space Telescope and the Sloan Digital Sky Survey, we investigate the FeII/MgII ratios of type 1 AGNs at z < 2. Over wide dynamic ranges of AGN properties (i.e., black hole mass, AGN luminosity, and Eddington ratio), we confirm that the FeII/MgII ratio strongly correlates with Eddington ratio but not with black hole mass, AGN luminosity, or redshift. Our results suggest tha…
We investigate FeII emission in Broad Line Region (BLR) of AGNs by analyzing the FeII(UV), FeII(4570) and MgII emission lines in 884 quasars in the Sloan Digital Sky Survey (SDSS) Quasar catalog in a redshift range of 0.727 < z < 0.804. FeII(4570)/FeII(UV) is used to infer the column density of FeII-emitting clouds and explore the excitation mechanism of FeII emission lines. As suggested before in various works, the classical photoionization models fail to account for FeII(4570)/FeII(UV) by a factor of 10, which may suggest anisotropy of UV FeII emission; otherwise, an alternative heating mech…
In AGN spectra, a series of FeII multiplets form a pseudo-continuum that extends from the ultraviolet to the near-infrared (NIR). This emission is believed to originate in the Broad Line Region (BLR), and it has been known for a long time that pure photoionization fails to reproduce it in the most extreme cases, as does the collisional-excitation alone. The most recent models by Sigut & Pradhan (2003) include details of the FeII ion microphysics and cover a wide range in ionization parameter log U_ion= (-3.0 -> -1.3) and density log n_H = (9.6 -> 12.6). With the aid of such models and a spectr…
The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical FeII strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L_Edd) of the black hole (BH) accretion. Shen & Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing FeII strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion sigma* (hence the BH mass via the M-sigma* relation) from decomposed…
Previous studies have shown that the incidence rate of intervening strong MgII absorbers towards GRBs were a factor of 2 - 4 higher than towards quasars. Exploring the similar sized and uniformly selected legacy data sets XQ-100 and XSGRB, each consisting of 100 quasar and 81 GRB afterglow spectra obtained with a single instrument (VLT/X-shooter), we demonstrate that there is no disagreement in the number density of strong MgII absorbers with rest-frame equivalent widths $W_r^{2796} >$ 1 Å towards GRBs and quasars in the redshift range 0.1 < z < 5. With large and similar sample sizes, and path…
We perform an analysis of the properties of radio-loud (RL) and radio-quiet (RQ) quasars with MgII broad emission line (i-band magnitude $\leq 19.1$ and z $\leq 1.9$), selected from the parent sample of SDSS DR7 catalogue. For sources with full-width half maxima (FWHM) greater than \mbox{15,000 km s$^{-1}$} (very broad line sample; VBL) we find the radio loud fraction (RLF) to be about 40\%. To further investigate this result we compare the bolometric luminosity, optical continuum luminosity, black hole (BH) mass and Eddington ratios of our VBL sample of RL and RQ quasars. Our analysis shows t…
Wavelength-resolved reverberation mapping of intermediate redshift quasars HE 0413-4031 and HE 0435-4312: Dissecting Mg II, optical Fe II, and UV Fe II emission regions
Using deep (11.2hr) VLT/MUSE data from the MEGAFLOW survey, we report the first detection of extended MgII emission from a galaxy's halo that is probed by a quasar sightline. The MgII $λλ$ 2796,2803 emission around the $z = 0.702$ galaxy ($\log(M_*/\mathrm{M_\odot}) = 10.05^{+0.15}_{-0.11}$) is detected out to $\approx$25 kpc from the central galaxy and covers $1.0\times10^3$ kpc$^2$ above a surface brightness of $14\times10^{-19} \mathrm{erg} \mathrm{s}^{-1} \mathrm{cm}^{-2}\,\mathrm{arcsec}^{-2}$ ($2 σ$; integrated over 1200 km s$^{-1}$ =19A and averaged over $1.5 \;\mathrm{arcsec}^2$). The …
The quasar class of extreme Population A (xA) (also known as super-Eddington accreting massive black holes, SEAMBHs) has been hailed as potential distance indicators for cosmology. The aim of this paper is to define tight criteria for their proper identification starting from the main selection criterion $R_{FeII} > 1 $, and to identify potential intruders not meeting the selection criteria, but nonetheless selected as xA because of the coarseness of automatic searches. Inclusion of the spurious xA sources may dramatically increase the dispersion in the Hubble diagram of quasars obtained from …
We present results from our search for HI 21-cm and OH 18-cm absorption at z~1-1.4 towards red quasars showing strong MgII absorption using uGMRT. The quasars J1501+1822 and J1521+5508 show multiple strong associated MgII absorption at z~1.1 and signature of reddening in their optical spectra. We report the detection of HI 21-cm absorption towards J1521+5508 at the systemic redshift of the quasar, with N(HI) =(1.2 +/- 0.2) x 10^{20} cm^{-2} for spin temperature of 100 K and unit covering factor. The HI 21-cm absorption is offset from the blueshifted strong MgII absorbers by >~1500 km/s. We do …
Extreme MgII Emission in Recently-Quenched Galaxies: A New Sample of Intermediate-Redshift Post-Starburst Quasars from the DESI Early Data Release
University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；The Johns Hopkins University（约翰斯·霍普金斯大学）；Princeton University（普林斯顿大学）；University of Nottingham（诺丁汉大学）；Space Telescope Science Institute（太空望远镜科学研究所）
We performed a detailed study of the extended cool gas, traced by MgII absorption [$W_r(2796)\geq0.3$~Å], surrounding 14 narrow-line active galactic nuclei (AGNs) at 0.12<z<0.22 using background quasar sight-lines. The background quasars probe the AGNs at projected distances of $60\leq D\leq265$~kpc. We find that, between $100\leq D\leq200$~kpc, AGNs appear to have lower MgII gas covering fractions (0.09$^{+0.18}_{-0.08}$) than quasars (0.47$^{+0.16}_{-0.15}$) and possibly lower than in active field galaxies (0.25$^{+0.11}_{-0.09}$). We do not find a statistically significant azimuthal angle d…
Built upon a sample of 134 quasars that was dedicated to a systematic study of \mgii-BAL variability from Yi et al. (2019a), we investigate these quasars showing \mgii-BAL disappearance or emergence with the aid of at least three epoch optical spectra sampled more than 15 yr in the observed frame. We identified 3/3 quasars undergoing pristine/tentative BAL transformations. The incidence of pristine BAL transformations in the sample is therefore derived to be 2.2$_{-1.2}^{+2.2}$\%, consistent with that of high-ionization BAL transformations from the literature. Adopting an average \mgii-BAL dis…
We present deep (9 hours) Gemini-N/GNIRS near-infrared spectroscopic observations of ULAS J1342+0928, a luminous quasar at z=7.54. Various broad emission lines were detected, as well as the underlying continuum and iron forests over the rest-frame wavelength 970-2930A. There is a clear trend that higher-ionization emission lines show larger blueshifts with CIV1549 exhibiting 5510^{+240}_{-110} km s-1 blueshift with respect to the systematic redshift from the far-infrared [CII] 158um emission line. Those high ionization lines have wide profiles with FWHM more than 10000 km s-1. A modest blueshi…
We present X-SHOOTER near-infrared spectroscopy of a large sample of 38 luminous ($M_{1450}=-29.0$ to $-24.4$) quasars at $5.78<z<7.54$, which have complementary CII observations from ALMA. This X-SHOOTER/ALMA sample provides us with the most comprehensive view of reionization-era quasars to date, allowing us to connect the quasar properties with those of its host galaxy. In this work we introduce the sample, discuss data reduction and spectral fitting, and present an analysis of the broad emission line properties. The measured FeII/MgII flux ratio suggests that the broad line regions of all q…
We present absorption variability results for 134 bona fide \mgii\ broad absorption line (BAL) quasars at 0.46~$\lesssim z \lesssim$~2.3 covering days to $\sim$ 10 yr in the rest frame. We use multiple-epoch spectra from the Sloan Digital Sky Survey, which has delivered the largest such BAL-variability sample ever studied. \mgii-BAL identifications and related measurements are compiled and presented in a catalog. We find a remarkable time-dependent asymmetry in EW variation from the sample, such that weakening troughs outnumber strengthening troughs, the first report of such a phenomenon in BA…
We present the Voigt profile (VP) models, column densities, Doppler b parameters, kinematics, and distribution of components for 422 MgII absorbers found in a survey of 249 HIRES and UVES quasar spectra. The equivalent width range of the sample is 0.006 < W_r(2796) < 6.23 angstroms (A) and the redshift range is 0.19 < z < 2.55, with a mean of <z> = 1.18. Based on historical precedent, we classified 180 absorbers as weak systems (W_r(2796) < 0.3 A) and 242 as strong systems (W_r(2796) >= 0.3 A). Assuming a minimum number of significant components per system, the VP fitting, yielded a total of 2…
We investigate the extent and the properties of the MgII cool, low-density absorbing gas located in the halo and in the circum-galactic environment of quasars, using a sample of 31 projected quasar pairs with impact parameter pd<200kpc in the redshift range 0.5<z<1.6. In the transverse direction, we detect 18 MgII absorbers associated with the foreground quasars, while no absorption system originated by the gas surrounding the quasar itself is found along the line-of-sight. This suggests that the quasar emission induces an anisotropy in the absorbing gas distribution. Our observations indicate…
We probe the spatial distribution of outflowing gas along four lines of sight separated by up to 6 kpc in a gravitationally-lensed star-forming galaxy at z=1.70. Using MgII and FeII emission and absorption as tracers, we find that the clumps of star formation are driving galactic outflows with velocities of -170 to -250 km/sec. The velocities of MgII emission are redshifted with respect to the systemic velocities of the galaxy, consistent with being back-scattered. By contrast, the FeII fluorescent emission lines are either slightly blueshifted or at the systemic velocity of the galaxy. Taken …
Using the six years of the spectroscopic monitoring of the luminous quasar HE 0435-4312 ($z=1.2231$) with the Southern African Large Telescope (SALT), in combination with the photometric data (CATALINA, OGLE, SALTICAM, and BMT), we determined the rest-frame time-delay of $296^{+13}_{-14}$ days between the MgII broad-line emission and the ionizing continuum using seven different time-delay inference methods. Artefact time-delay peaks and aliases were mitigated using the bootstrap method, prior weighting probability function as well as by analyzing unevenly sampled mock light curves. The MgII em…
We explore the variability of quasars in the MgII and Hbeta broad emission lines and UV/optical continuum emission using the Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic study of quasar variability to date: our study includes 29 spectroscopic epochs from SDSS-RM over $6$ months, containing 357 quasars with MgII and 41 quasars with Hbeta . On longer timescales, the study is also supplemented with two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional $2854$ quasars with MgII and 572 quasars with Hbeta. The MgII emission lin…
Reverberation mapping (RM) measurements of broad-line region (BLR) lags in z>0.3 quasars are important for directly measuring black hole masses in these distant objects, but so far there have been limited attempts and success given the practical difficulties of RM in this regime. Here we report preliminary results of 15 BLR lag measurements from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project, a dedicated RM program with multi-object spectroscopy designed for RM over a wide redshift range. The lags are based on the 2014 spectroscopic light curves alone (32 epochs over 6 mo…
Extreme Enrichment at Cosmic Dawn: Three FeII-Strong Quasars at z > 6 from the JWST Aether survey
NSF NOIRLab, Gemini Observatory（美国国家光学红外天文实验室，双子座天文台）；International Gemini Observatory/NSF NOIRLab（国际双子座天文台/美国国家光学红外天文实验室）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚天文与空间科学观测站）；Institute for Theoretical Physics, Heidelberg University（海德堡大学理论物理研究所）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；INAF-Osservatorio di Astrofisica e Scienza dello Spazio（意大利国家天体物理研究所天文与空间科学观测站）；Dipartimento di Fisica Enrico Fermi, Università di Pisa（比萨大学恩里科·费米物理系）
Quasar-galaxy pairs at small separations are important probes of gas flows in the disk-halo interface in galaxies. We study host galaxies of 198 MgII absorbers at $0.39\le z_{abs}\le1.05$ that show detectable nebular emission lines in the SDSS spectra. We report measurements of impact parameter (5.9$\le D[kpc]\le$16.9) and absolute B-band magnitude ($-18.7\le {\rm M_B}\le -22.3$ mag) of host galaxies of 74 of these absorbers using multi-band images from the DESI Legacy Imaging Survey, more than doubling the number of known host galaxies with $D\le17$ kpc. This has allowed us to quantify the re…
We investigate the variation of the ratio of the equivalent widths of the FeII$λ$2600 line to the MgII$λλ$2796,2803 doublet as a function of redshift in a large sample of absorption lines drawn from the JHU-SDSS Absorption Line Catalog. We find that despite large scatter, the observed ratio shows a trend where the equivalent width ratio $\mathcal{R}\equiv W_{\rm FeII}/W_{\rm MgII}$ decreases monotonically with increasing redshift $z$ over the range $0.55 \le z \le 1.90$. Selecting the subset of absorbers where the signal-to-noise ratio of the MgII equivalent width $W_{\rm MgII}$ is $\ge$3 and …
We investigate the relationship between the MgII $\lambda2798$ emission-line and the 3000 Å continuum variations using a sample of 68 intermediate-redshift ($z\sim$ 0.65$-$1.50) broad-line quasars spanning a bolometric luminosity range of 44.49 erg s$^{-1} \leq \rm{log}$$L_{\rm{bol}} \leq 46.31$ erg s$^{-1}$ (Eddington ratio from $\sim$ 0.026 to 0.862). This sample is constructed from SDSS-DR7Q and BOSS-DR12Q, each with at least 2 spectroscopic epochs in SDSS-I/II/III surveys. Additionally, we adopt the following signal-to-noise ratio (S/N) selection criteria: a) for MgII and the 3000 Å contin…
We present reverberation mapping results for the MgII 2800 A broad emission line in a sample of 193 quasars at 0.35<z<1.7 with photometric and spectroscopic monitoring observations from the Sloan Digital Sky Survey Reverberation Mapping project during 2014 - 2017. We find significant time lags between the MgII and continuum lightcurves for 57 quasars and define a "gold sample" of 24 quasars with the most reliable lag measurements. We estimate false-positive rates for each lag that range from 1-24%, with an average false-positive rate of 11% for the full sample and 8% for the gold sample. There…
We address the effect of orientation of the accretion disk plane and the geometry of the broad-line region (BLR) as part of an effort to understand the distribution of quasars in the optical plane of the quasar main sequence. We utilize the photoionization code CLOUDY to model the BLR incorporating the grossly underestimated form factor ($f$). Treating the aspect of viewing angle appropriately, we confirm the dependence of the $R_{\mathrm{FeII}}$ sequence on Eddington ratio and on the related observational trends - as a function of the SED shape, cloud density and composition, verified from pr…
It is widely believed that the cool gas clouds traced by MgII absorption, within a velocity offset of 5000 km/s relative to the background quasar are mostly associated with the quasar itself, whereas the absorbers seen at larger velocity offsets towards us are intervening absorber systems and hence their existence is completely independent of the background quasar. Recent evidence by Bergeron et al. (2011, hereinafter BBM) has seriously questioned this paradigm, by showing that the number density of intervening MgII absorbers towards the 45 blazars in their sample is nearly 2 times the expecta…
We built the first-ever statistically significant sample of ~ 80,000 background quasar - foreground cluster pairs to study the cool, metal-rich gas in the outskirts (> R500) of z ~ 0.5 clusters with a median mass of ~ 10^14.2 M_sun. The sample was obtained by cross-matching the SDSS cluster catalog of Wen & Han (2015) and SDSS quasar catalog of Lyke et al. (2020). The median impact parameter (rho_cl) of the clusters from the quasar sightlines is 2.4 Mpc (median rho_cl/R500 = 3.6). A strong MgII, along with marginal FeII, absorption is detected in the mean and median stacked spectra of the quas…
We find multiple Mg II absorption systems at redshift z=1.66, 2.069, and 2.097 in the spatially resolved spectra of the quadruply gravitationally lensed quasar H1413+1143 utilizing the Kyoto tridimensional spectrograph II (Kyoto 3DII) spectrograph on board the Subaru telescope. Here we present the first measurement of differences in Mg II absorption strength of the multiple intervening absorbers, which include ones identified as damped Lyman alpha (DLA) absorption systems. Our detection of the significant Mg II absorptions in the spatially resolved spectra reveals the inhomogeneous chemical en…
We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the DR11 main galaxy sample of the Baryon Oscillation Spectroscopic Survey of SDSS-III (CMASS galaxies), and the DR7 quasar spectra of SDSS-II. The cross-correlation is measured by stacking quasar absorption spectra shifted to the redshift of galaxies that are within a certain impact parameter bin of the quasar, after dividing by a quasar continuum model. This results in an average MgII equivalent width as a function of impact parameter from a galaxy, ranging from 50 kpc to more than 10 Mpc in prop…
Using the MEGAFLOW survey, which consists of a combination of MUSE and UVES observations of 22 quasar fields selected to contain strong MgII absorbers, we measure covering fractions of CIV and MgII as a function of impact parameter $b$ using a novel Bayesian logistic regression method on unbinned data, appropriate for small samples. We also analyse how the CIV and MgII covering fractions evolve with redshift. In the MUSE data, we found 215 $z=1-1.5$ [OII] emitters with fluxes $>10^{-17}$ erg\,s$^{-1}$\,cm$^{-2}$ and within 250 kpc of quasar sight-lines. Over this redshift path $z=1-1.5$, we ha…
Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for Mg II narrow absorption doublets in the spectra data around Mg II emission lines. We obtain 17,316 Mg II doublets, within the redshift range of 0.3299<= z_abs <= 2.5663. We find that a velocity offset of v_r < 6000 km/s is a safe boundary to constrain the vast majority of associated Mg II systems, although we find some doublets at v_r > 6000 km/s. If associated Mg II absorbers are defined by v_r < 6000 km/s, ~33.3% of the absorbers supposed to be contaminants of intervening systems. Removing the 33.3% conta…
To study environmental effects on the circumgalactic medium (CGM), we use the samples of redMaPPer galaxy clusters, background quasars and cluster galaxies from the SDSS. With ~82 000 quasar spectra, we detect 197 MgII absorbers in and around the clusters. The detection rate per quasar is 2.7$\pm$0.7 times higher inside the clusters than outside the clusters, indicating that MgII absorbers are relatively abundant in clusters. However, when considering the galaxy number density, the absorber-to-galaxy ratio is rather low inside the clusters. If we assume that MgII absorbers are mainly contribut…
Lobe-dominated radio-loud (LD RL) quasars occupy a restricted domain in the 4D Eigenvector 1 (4DE1) parameter space which implies restricted geometry/physics/kinematics for this subclass compared to the radio-quiet (RQ) majority of quasars. We discuss how this restricted domain for the LD RL parent population supports the notion for a RQ-RL dichotomy among Type 1 sources. 3C 57 is an atypical RL quasar that shows both uncertain radio morphology and falls in a region of 4DE1 space where RL quasars are rare. We present new radio flux and optical spectroscopic measures designed to verify its atyp…
We present an observational study of 22 broad absorption line quasars (BAL QSOs) at $3\lesssim z \lesssim5$ based on optical/near-IR spectroscopy, aiming to investigate quasar winds and their effects. The near-IR spectroscopy covers the \hb\ and/or \mgii\ broad emission lines (BELs) for these quasars, allowing us to estimate their central black hole (BH) masses in a robust way. We found that our BAL QSOs on average do not have a higher Eddington ratio than that from non-BAL QSOs matched in redshift and/or luminosity. In a subset consisting of seven strong BAL QSOs possessing sub-relativistic B…
We present the first near-IR spectroscopy and joint analyses of multi-wavelength observations for SDSS J082747.14+425241.1, a dust-reddened, weak broad emission-line quasar (WLQ) undergoing a remarkable broad absorption line (BAL) transformation. The systemic redshift is more precisely measured to be $z=2.070\pm0.001$ using H$β$ compared to $z=2.040\pm0.003$ using \mgii\ from the literature, signifying an extreme \mgii\ blueshift of $2140\pm530$ \kms\ relative to H$β$. Using the H$β$-based single-epoch scaling relation with a systematic uncertainty of 0.3 dex, its black hole (BH) mass and Eddi…
We address the effect of the viewing angle of the accretion disk plane and the geometry of the broad-line region (BLR) with the goal of interpreting the distribution of quasars along the main sequence (MS). We utilize photoionization code CLOUDY to model the BLR FeII emission, incorporating the grossly underestimated role of the form factor (f). We recover the dependence of the strength of the FeII emission in the optical (R$_{\rm{FeII}}$) on L$_{\rm{bol}}$/L$_{\rm{Edd}}$ ratio and related observational trends - as a function of the spectral energy distribution (SED) shape, cloud density, comp…
We present the monitoring of the AGN continuum and MgII broad line emission for the quasar HE 0413-4031 ($z=1.38$) based on the six-year monitoring by the South African Large Telescope (SALT). We managed to estimate a time-delay of $302.6^{+28.7}_{-33.1}$ days in the rest frame of the source using seven different methods: interpolated cross-correlation function (ICCF), discrete correlation function (DCF), $z$-transformed DCF, JAVELIN, two estimators of data regularity (Von Neumann, Bartels), and $χ^2$ method. This time-delay is below the value expected from the standard radius-luminosity relat…
We present joint constraints on the distribution of MgII absorption around galaxies, by combining the MgII absorption seen in stacked background galaxy spectra and the distribution of host galaxies of strong MgII systems from the spectra of background quasars. We present a suite of models that predict, the dependence of MgII absorption on a galaxy's apparent inclination, impact parameter(b) and azimuthal angle. The variations in the absorption strength with azimuthal angles provide much stronger constraints on the intrinsic geometry of the MgII absorption than the dependence on the galaxy's in…
Quasar outflows are fundamental components of quasar environments that might play an important role in feedback to galaxy evolution. We report on the emergence of a remarkable new outflow absorption-line system in the quasar PG1411+442 (redshift ~0.089) detected in the UV and visible with the Hubble Space Telescope Cosmic Origins Spectrograph and the Gemini Multi-Object Spectrograph, respectively. This new "transient'' system contains thousands of lines, including FeII and FeII* from excited states up to 3.89 eV, HI* Balmer lines, NaI D 5890,5896, and the first detection of HeI* 5876 in a quas…
Size and kinematics of the low-ionization broad emission line region from microlensing-induced line profile distortions in gravitationally lensed quasars
Eigenvector 1 (EV1) was found to be the dominant component behind the significant correlations for the measured parameters in quasar spectra (Boroson & Green, 1992). The parameter R$_{\mathrm{FeII}}$, which strongly correlates to the EV1, is the ${\mathrm{FeII}}$ strength, defined to be the ratio of the equivalent width of ${\mathrm{FeII}}$ to the equivalent width of ${\mathrm{Hβ}}$. This allows to construct a quasar main sequence analogous to the stellar properties driven HR diagram (Sulentic et al. 2001). We try to find the main driver behind the EV1 among the basic (theoretically motivated)…
The interpretation of the main sequence of quasars has become a frontier subject in the last years. The consider the effect of a highly flattened, axially symmetric geometry for the broad-line region (BLR) on the parameters related to the distribution of quasars along their Main Sequence. We utilize the photoionization code CLOUDY to model the BLR, assuming `un-constant' virial factor with a strong dependence on the viewing angle. We show the preliminary results of the analysis to highlight the co-dependence of the Eigenvector 1 parameter, R$_{\mathrm{FeII}}$ on the broad H$β$ FWHM (i.e. the l…
We present new near-infrared (IR) observations of the H$β \lambda4861$ and MgII $\lambda2798$ lines for 32 luminous quasars with $3.2<z<3.9$ using the Palomar Hale 200 inch telescope and the Large Binocular Telescope. We find that the MgII Full Width at Half Maximum (FWHM) is well correlated with the H$β$ FWHM, confirming itself as a good substitute for the H$β$ FWHM in the black hole mass estimates. The continuum luminosity at 5100 Å well correlates with the continuum luminosity at 3000 Å and the broad emission line luminosities (H$β$ and MgII). With simultaneous near-IR spectroscopy of the H…
