Abstract
The most rapidly evolving regions of galaxies often display complex optical spectra with emission lines excited by massive stars, shocks and accretion on to supermassive black holes. ...Standard calibrations (such as for the star formation rate) cannot be applied to such mixed spectra. In this paper, we isolate the contributions of star formation, shock excitation and active galactic nucleus (AGN) activity to the emission line luminosities of individual spatially resolved regions across the central 3 × 3 kpc2 region of the active barred spiral galaxy NGC 613. The star formation rate and AGN luminosity calculated from the decomposed emission line maps are in close agreement with independent estimates from data at other wavelengths. The star formation component traces the B-band stellar continuum emission, and the AGN component forms an ionization cone which is aligned with the nuclear radio jet. The optical line emission associated with shock excitation is cospatial with strong H2 and Fe II emission and with regions of high ionized gas velocity dispersion (σ ≳ 100 km s−1). The shock component also traces the outer boundary of the AGN ionization cone and may therefore be produced by outflowing material interacting with the surrounding interstellar medium. Our decomposition method makes it possible to determine the properties of star formation, shock excitation and AGN activity from optical spectra, without contamination from other ionization mechanisms.
Abstract
Weak emission-line quasars (WLQs) are a subset of type 1 quasars that exhibit extremely weak Ly
α
+ N
v
λ
1240 and/or C
iv
λ
1549 emission lines. We investigate the relationship between ...emission-line properties and accretion rate for a sample of 230 “ordinary” type 1 quasars and 18 WLQs at
z
< 0.5 and 1.5 <
z
< 3.5 that have rest-frame ultraviolet and optical spectral measurements. We apply a correction to the H
β
-based black hole mass (
M
BH
) estimates of these quasars using the strength of the optical Fe
ii
emission. We confirm previous findings that WLQs’
M
BH
values are overestimated by up to an order of magnitude using the traditional broad-emission-line region size–luminosity relation. With this
M
BH
correction, we find a significant correlation between H
β
-based Eddington luminosity ratios and a combination of the rest-frame C
iv
equivalent width and C
iv
blueshift with respect to the systemic redshift. This correlation holds for both ordinary quasars and WLQs, which suggests that the two-dimensional C
iv
parameter space can serve as an indicator of accretion rate in all type 1 quasars across a wide range of spectral properties.
Abstract We report first-time reverberation-mapping results for 14 active galactic nuclei (AGNs) from the ongoing Monitoring AGNs with H β Asymmetry campaign (MAHA). These results utilize optical ...spectra obtained with the Long Slit Spectrograph on the Wyoming Infrared 2.3 m Telescope between 2017 November and 2023 May. MAHA combines long-duration monitoring with high cadence. We report results from multiple observing seasons for nine of the 14 objects. These results include H β time lags, supermassive black hole masses, and velocity-resolved time lags. The velocity-resolved lags allow us to investigate the kinematics of the broad-line region.
The aim of this thesis is to provide a multiwavelength perspective of the fundamental properties of quasars. It improves the statistical measure of quasar orientation and their black hole mass ...estimates by eliminating systematic biases. This work illustrates X-ray and optical-UV properties of some of the most highly accreting quasars. A crucial step to determine radio core dominance, an orientation indicator, is to get the most accurate measurement of the Doppler-boosted core of jets. The isotropic lobe emission likely contaminates the core measurements from large area surveys with poor resolution. I empirically show that orientation studies require high spatial resolution radio data. Because of various practical issues and variability considerations, optical emission provides a better normalization for the core dominance parameter than the extended emission. The black hole mass and accretion rate are the two most fundamental properties of quasars. Virial mass estimation from single-epoch spectra relies on the linear relationship between the broad line region size and continuum luminosity. More recent reverberation mapping results indicate deviation from the canonical radius-luminosity relationship that correlates with accretion rate. Using a radius-luminosity relationship that corrects the accretion rate bias, I establish a new prescription of virial mass estimates. I quantify the overestimation of the viral masses in the absence of accretion rate correction for quasars spanning a wide range of redshifts. The overestimation increases as redshift increases. Quasars that exhibit systematically smaller broad-line region size in the reverberation mapping studies also have higher accretion rates. They are ideal candidates to test for observable signatures of highly accreting disks. I examine the X-ray and optical-UV properties of a dozen super-Eddington accreting black holes that show extreme deviation from the canonical radius-luminosity relationship. Super-Eddington accreting sources demonstrate a steeper hard X-ray photon index compared to sub-Eddington accreting sources. The power-law slope between optical-UV and X-rays steepens as disk emission increases. These results illustrate that the disk-corona connection stays unchanged in quasars accreting at super-Eddington rates.
We have started a long-term reverberation mapping (RM) project using the Wyoming Infrared Observatory 2.3 m telescope titled "Monitoring AGNs with Hβ Asymmetry" (MAHA). The motivations of the project ...are to explore the geometry and kinematics of the gas responsible for complex Hβ emission-line profiles, ideally leading to an understanding of the structures and origins of the broad-line region (BLR). Furthermore, such a project provides the opportunity to search for evidence of close binary supermassive black holes. We describe MAHA and report initial results from our first campaign, from 2016 December to 2017 May, highlighting velocity-resolved time lags for four active galactic nuclei (AGNs) with asymmetric Hβ lines. We find that 3C 120, Ark 120, and Mrk 6 display complex features different from the simple signatures expected for pure outflow, inflow, or a Keplerian disk. While three of the objects have been previously reverberation mapped, including velocity-resolved time lags in the cases of 3C 120 and Mrk 6, we report a time lag and corresponding black hole mass measurement for SBS 1518+593 for the first time. Furthermore, SBS 1518+593, the least asymmetric of the four, does show velocity-resolved time lags characteristic of a Keplerian disk or virialized motion more generally. Also, the velocity-resolved time lags of 3C 120 have significantly changed since previously observed, indicating an evolution of its BLR structure. Future analyses of the data for these objects and others in MAHA will explore the full diversity of Hβ lines and the physics of AGN BLRs.
ABSTRACT
X-ray properties of active galactic nuclei (AGNs) depend on their underlying physical parameters, particularly the accretion rate. We identified eight reverberation-mapped AGNs with some of ...the largest known accretion rates without high-quality X-ray data. We obtained new Chandra ACIS-S X-ray observations and nearly simultaneous optical spectrophotometry to investigate the properties of these AGNs with extreme super-Eddington accreting massive black holes (SEAMBHs). We combined our new X-ray measurements with those of other reverberation-mapped AGNs, which have the best-determined masses and accretion rates. The trend of the steepening of the spectral slope between X-ray and optical-UV, αox, with increasing optical-UV luminosity, $L_{\rm 2500{\mathring{\rm A}}}$, holds true for even the most extreme SEAMBHs. One of our new SEAMBHs appears X-ray-weak for its luminosity, perhaps due to absorption associated with orientation effects involving a slim disc thought to be present in highly accreting systems. The correlation of the $\rm 2\!-\!8~ keV$ X-ray photon index with the accretion rate also holds for the extreme SEAMBHs, which show some of the largest photon indices reported for AGNs.
ABSTRACT
Determining black hole masses and accretion rates with better accuracy and precision is crucial for understanding quasars as a population. These are fundamental physical properties that ...underpin models of active galactic nuclei. A primary technique to measure the black hole mass employs the reverberation mapping of low-redshift quasars, which is then extended via the radius–luminosity relationship for the broad-line region to estimate masses based on single-epoch spectra. An updated radius–luminosity relationship incorporates the flux ratio of optical Fe ii to H β ($\equiv \mathcal {R}_{\rm Fe}$) to correct for a bias in which more highly accreting systems have smaller line-emitting regions than previously realized. In this work, we demonstrate and quantify the effect of using this Fe-corrected radius-luminosity relationship on mass estimation by employing archival data sets possessing rest-frame optical spectra over a wide range of redshifts. We find that failure to use an Fe-corrected radius predictor results in overestimated single-epoch black hole masses for the most highly accreting quasars. Their accretion rate measures (LBol/LEdd and $\dot{\mathscr{M}}$ ) are similarly underestimated. The strongest Fe-emitting quasars belong to two classes: high-z quasars with rest-frame optical spectra, which, given their extremely high luminosities, require high accretion rates, and their low-z analogues, which, given their low black holes masses, must have high accretion rates to meet survey flux limits. These classes have mass corrections downward of about a factor of two, on average. These results strengthen the association of the dominant Eigenvector 1 parameter $\mathcal {R}_{\rm Fe}$ with the accretion process.
We report the results of reverberation mapping of three bright Seyfert galaxies, Mrk 79, NGC 3227, and Mrk 841, from a campaign conducted from 2016 December to 2017 May with the Wyoming Infrared ...Observatory (WIRO) 2.3 m telescope. All three of these targets have shown asymmetric broad Hβ emission lines in the past, although their emission lines were relatively symmetric during our observations. We measured Hβ time lags for all three targets and estimated masses of their black holes-for the first time in the case of Mrk 841. For Mrk 79 and NGC 3227, the data are of sufficient quality to resolve distinct time lags as a function of velocity and to compute two-dimensional velocity-delay maps. Mrk 79 shows smaller time lags for high-velocity gas, but the distribution is not symmetric, and its complex velocity-delay map could result from the combination of both inflowing and outflowing Hβ emitting disks that may be part of a single larger structure. NGC 3227 shows the largest time lags for blueshifted gas, and the two-dimensional velocity-delay map suggests a disk with some inflow. We compare our results with previous work and find evidence for different time lags despite similar luminosities, as well as evolving broad-line region structures.
Abstract
In this third paper of the series reporting on the reverberation mapping campaign of active galactic nuclei with asymmetric H
β
emission-line profiles, we present results for 15 ...Palomar–Green quasars using spectra obtained between the end of 2016–2021 May. This campaign combines long time spans with relatively high cadence. For eight objects, both the time lags obtained from the entire light curves and the measurements from individual observing seasons are provided. Reverberation mapping of nine of our targets has been attempted for the first time, while the results for six others can be compared with previous campaigns. We measure the H
β
time lags over periods of years and estimate their black hole masses. The long duration of the campaign enables us to investigate their broad-line region (BLR) geometry and kinematics for different years by using velocity-resolved lags, which demonstrate signatures of diverse BLR geometry and kinematics. The BLR geometry and kinematics of individual objects are discussed. In this sample, the BLR kinematics of Keplerian/virialized motion and inflow is more common than that of outflow.
Radio core dominance measurements, an indicator of jet orientation, sometimes rely on core flux density measurements from large-area surveys like Faint Images of the Radio Sky at Twenty cm (FIRST) ...that have an angular resolution of only 5″. Such low-resolution surveys often fail to resolve cores from the extended emission, resulting in an erroneous measurement. We focus on investigating this resolution effect for a sample of 119 radio-loud quasars. We obtained continuum observations from NSF's Karl G. Jansky Very Large Array (VLA) at 10 GHz in A configuration with a 0 2 resolution. Our measurements show that at FIRST spatial resolution, core flux measurements are indeed systematically high even after considering the core variability. For a handful of quasars, 10 GHz images reveal extended features, whereas the FIRST image shows a point source. We found that the resolution effect is more prominent for quasars with smaller angular sizes. We further computed two radio core dominance parameters R and R5100 for use in statistical orientation investigations with this sample. We also present the spectral energy distributions between 74 MHz and 1.4 GHz, which we used to measure the spectral index of the extended emission of these quasars. Our results empirically confirm that determination of radio core dominance requires high spatial resolution data. We highlight the practical issues associated with the choice of frequency and resolution in the measurement of core and extended flux densities.
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