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61. BeppoSAX HELLAS survey. V.
ID:
ivo://CDS.VizieR/J/ApJ/570/100
Title:
BeppoSAX HELLAS survey. V.
Short Name:
J/ApJ/570/100
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical spectroscopic identifications of hard X-ray (5-10keV) selected sources belonging to the High-Energy Large-Area Survey sample obtained with BeppoSAX down to a 5-10keV flux limit of F(5-10kev)~3x10^-14^erg/cm^2^/s. The sample consists of 118 sources. There are 25 sources that have been identified through correlations with catalogs of known sources. A spectroscopic identification for 49 more has been searched for with the telescope. The results of 13 fields were empty down to R=21. There were 37 sources identified as type 1 active galactic nuclei (AGNs) and nine as type 2 AGNs. The remaining sources are five narrow emission-line galaxies, six clusters, two BL Lac objects, one radio galaxy, and one star.
62. BeppoSAX HELLAS survey. VI.
ID:
ivo://CDS.VizieR/J/MNRAS/342/575
Title:
BeppoSAX HELLAS survey. VI.
Short Name:
J/MNRAS/342/575
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a complete radio follow-up obtained with the VLA and ATCA radio telescopes down to a 6-cm flux limit of about 0.3 mJy (3{sigma}) of all the 147 X-ray sources detected in the BeppoSAX HELLAS survey. We found 53 X-ray/radio likely associations, corresponding to about one-third of the X-ray sample. Using the two-point spectral index {alpha}_ro_=0.35 we divided all the HELLAS X-ray sources into radio-quiet and radio-loud. We have 26 sources classified as radio-loud objects, corresponding to 18 per cent of the HELLAS sample. In agreement with previous results, the identified radio-loud sources are associated mainly with Type 1 active galactic nuclei (AGNs) with L_5-10kev_>~10^44^erg/s, while all the identified Type 2 AGNs and emission-line galaxies are radio-quiet objects with L_5-10kev_<~10^44^erg/s.
63. BH masses and Eddington ratios of Type 2 QSOs
ID:
ivo://CDS.VizieR/J/ApJ/859/116
Title:
BH masses and Eddington ratios of Type 2 QSOs
Short Name:
J/ApJ/859/116
Date:
21 Oct 2021
Publisher:
CDS
Description:
Type 2 quasars are an important constituent of active galaxies, possibly representing the evolutionary precursors of traditionally studied type 1 quasars. We characterize the black hole (BH) mass (MBH) and Eddington ratio (Lbol/LEdd) for 669 type 2 quasars selected from the Sloan Digital Sky Survey, using BH masses estimated from the MBH-{sigma}* relation and bolometric corrections scaled from the extinction-corrected [OIII]{lambda}5007 luminosity. When stellar velocity dispersions cannot be measured directly from the spectra, we estimate them from the core velocity dispersions of the narrow emission lines [OII]{lambda}{lambda}3726,3729, [SII]{lambda}{lambda}6716,6731, and [OIII]{lambda}5007, which are shown to trace the gravitational potential of the stars. Energy input from the active nucleus still imparts significant perturbations to the gas kinematics, especially to high-velocity, blueshifted wings. Nonvirial motions in the gas become most noticeable in systems with high Eddington ratios. The BH masses of our sample of type 2 quasars range from MBH~10^6.5^ to 10^10.4^M_{sun}_ (median 10^8.2^M_{sun}_). Type 2 quasars have characteristically large Eddington ratios (Lbol/LEdd~10^-2.9^-10^1.8^; median 10^-0.7^), slightly higher than in type 1 quasars of similar redshift; the luminosities of ~20% of the sample formally exceed the Eddington limit. The high Eddington ratios may be consistent with the notion that obscured quasars evolve into unobscured quasars.
64. BH masses & host galaxy dispersion vel.
ID:
ivo://CDS.VizieR/J/ApJ/831/134
Title:
BH masses & host galaxy dispersion vel.
Short Name:
J/ApJ/831/134
Date:
21 Oct 2021
Publisher:
CDS
Description:
According to the virial theorem, all gravitational systems in equilibrium sit on a plane in the three-dimensional parameter space defined by their mass, size, and second moment of the velocity tensor. While these quantities cannot be directly observed, there are suitable proxies: the luminosity L_k_, half-light radius R_e_, and dispersion {sigma}_e_. These proxies indeed lie on a very tight fundamental plane (FP). How do the black holes (BHs) in the centers of galaxies relate to the FP? Their masses are known to exhibit no strong correlation with total galaxy mass, but they do correlate weakly with bulge mass (when present), and extremely well with the velocity dispersion through the M_{bullet}_{propto}{sigma}_e_^5.4^ relation. These facts together imply that a tight plane must also exist defined by BH mass, total galaxy mass, and size. Here, I show that this is indeed the case using a heterogeneous set of 230 BHs. The sample includes BHs from zero to 10 billion solar masses and host galaxies ranging from low surface brightness dwarfs, through bulgeless disks, to brightest cluster galaxies. The resulting BH-size-luminosity relation M_{bullet}_{propto}(L_k_/R_e_)^3.8^ has the same amount of scatter as the M_*_-{sigma} relation and is aligned with the galaxy FP, such that it is just a reprojection of {sigma}_e_. The inferred BH-size-mass relation is M_{bullet}_{propto}(M_*_/R_e_)^2.9^. These relationships are universal and extend to galaxies without bulges. This implies that the BH is primarily correlated with its global velocity dispersion and not with the properties of the bulge. I show that the classical bulge-mass relation is a projection of the M_*_-{sigma} relation. When the velocity dispersion cannot be measured (at high z or low dispersions), the BH-size-mass relation should be used as a proxy for BH mass in favor of just galaxy or bulge mass.
65. Bimodal radio variability in OVRO blazars
ID:
ivo://CDS.VizieR/J/MNRAS/467/4565
Title:
Bimodal radio variability in OVRO blazars
Short Name:
J/MNRAS/467/4565
Date:
21 Oct 2021
Publisher:
CDS
Description:
Blazars are known to show periods of quiescence followed by outbursts visible throughout the electromagnetic spectrum. We present a novel maximum likelihood approach to capturing this bimodal behavior by examining blazar radio variability in the flux-density domain. We separate quiescent and flaring components of a source's light curve by modeling its flux-density distribution as a series of "off" and "on" states. Our modeling allows us to extract information regarding the flaring ratio, duty cycle, and the modulation index in the "off"-state, in the "on"-state, as well as throughout the monitoring period of each blazar. We apply our method to a flux-density-limited subsample from the Owens Valley Radio observatory's 15 GHz blazar monitoring program, and explore differences in the variability characteristics between BL Lacs and FSRQs as well as between {gamma}-ray detected and non-detected sources. We find that: (1) BL Lacs are more variable and have relatively larger outbursts than the FSRQs; (2) unclassified blazar candidates in our sample show similar variability characteristics as the FSRQs; and (3) {gamma}-ray detected differ from the {gamma}-ray non-detected sources in all their variability properties, suggesting a link between the production of {gamma}-rays and the mechanism responsible for the radio variability. Finally, we fit distributions for blazar flaring ratios, duty cycles, and on- and off- modulation indices that can be used in population studies of variability-dependent blazar properties.
66. Binary quasars from LQAC-2
ID:
ivo://CDS.VizieR/J/A+A/564/A117
Title:
Binary quasars from LQAC-2
Short Name:
J/A+A/564/A117
Date:
21 Oct 2021
Publisher:
CDS
Description:
Thanks to huge surveys, such as the Sloan Digital Sky Survey (SDSS), the last decade has shown a dramatic increase in the number of known quasars. In the second release of the general compiled catalogue Large Quasar Astrometric Catalogue (LQAC), 187504 objects are recorded. From this catalogue, we carry out statistical studies dealing with several topics: the astrometric accuracy of the quasars, their spatial location, the distribution of the distance to the closest neighbour, the identification of binary quasars, the completness of catalogues at a given magnitude and the estimation of the number of quasars expected to be detected by the astrometric space mission Gaia. We analyse the astrometric improvements brought by the LQAC-2 in terms of equatorial coordinates off-sets. We plot the bi-dimensional spatial distribution of the LQAC-2 quasars according to their equatorial, galactic, and ecliptic coordinates, thus exploring the anisotropy of the distribution. We compare the observed distribution of closest neighbours with the theoretical values based on a Poisson distribution. Moreover, we perform a comparison between two catalogues, the SDSS and the 2dF inside a huge common field. By extrapolating to the whole sky we deduce the number of quasars that will be detected by Gaia.
67. Binary quasars in the SDSS
ID:
ivo://CDS.VizieR/J/AJ/131/1
Title:
Binary quasars in the SDSS
Short Name:
J/AJ/131/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a sample of 221 new quasar pairs with proper transverse separations R_prop_<1h^1^Mpc over the redshift range 0.5<z<3.0, discovered from an extensive follow-up campaign to find companions around the Sloan Digital Sky Survey (Cat. <VII/243>) and 2dF QSO Redshift Survey (Cat. <VII/241>) quasars. This sample includes 26 new binary quasars with separations R_prop_<50h^-1^kpc ({thetas}<10"), more than doubling the number of such systems known. We define a statistical sample of binaries selected with homogeneous criteria and compute its selection function, taking into account sources of incompleteness. The first measurement of the quasar correlation function on scales 10h^-1^kpc<R_prop_<400h^-1^kpc is presented.
68. b_j_ur photometry and redshifts of QSOs
ID:
ivo://CDS.VizieR/J/MNRAS/357/1267
Title:
b_j_ur photometry and redshifts of QSOs
Short Name:
J/MNRAS/357/1267
Date:
21 Oct 2021
Publisher:
CDS
Description:
The quasar sample selected by cross-correlating the Faint Images of the Radio Sky at Twenty cm (FIRST, <VIII/71>) survey and the 2-degree Field Quasar Redshift Survey (2QZ, <VII/223>) allows us to explore, for the first time, the faint end of the radio and optical luminosity functions up to z=~2.2. We find indications (~3{sigma}) of a negative evolution for these faint sources at z>~1.8, both in radio and optical bands. This corresponds to a decrement in the space density of faint quasars of approximately a factor 2 at z=2.2 and confirms the presence of a differential evolution for the population of radio-active quasars. The faint end of both luminosity functions flattens and the comparison with the (optical) number density of the whole quasar population supports a dependence of the fraction of radio-detected quasars on the optical luminosity. A progressive decrease in the fraction of quasars in the whole radio source population can be consistently accounted for within the receding torus scenario. The population of low-luminosity quasars, which the FIRST-2dF detects, appears to depart from the classical scheme for radio-loud quasars.
69. Black hole mass and accretion rate of AGNs
ID:
ivo://CDS.VizieR/J/ApJ/614/91
Title:
Black hole mass and accretion rate of AGNs
Short Name:
J/ApJ/614/91
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using an empirical relation between the broad-line region size and optical continuum luminosity, we estimated the black hole mass and accretion rate for 135 active galactic nuclei (AGNs) with double-peaked broad emission lines in two samples, one from the Sloan Digital Sky Survey (SDSS, Cat. <J/AJ/126/2579>) and the other from a survey of radio-loud broad emission line AGNs (Eracleous & Halpern, 2003, Cat. <J/ApJ/599/886>).
70. BLAGNs and NLS1s characteristics.
ID:
ivo://CDS.VizieR/J/MNRAS/478/4068
Title:
BLAGNs and NLS1s characteristics.
Short Name:
J/MNRAS/478/4068
Date:
10 Dec 2021 00:54:07
Publisher:
CDS
Description:
investigated narrow-line Seyfert 1 galaxies (NLS1s) at optical, mid-infrared (MIR), and X-ray wavelengths, comparing them to the broad-line active galactic nuclei (BLAGNs). We found that black hole mass, coronal line luminosities, X-ray hardness ratio and X-ray, and optical and MIR luminosities are higher for the BLAGNs than for NLS1s, while policyclic aromatic hydrocarbon (PAH) contribution and the accretion rates are higher for NLS1s. Furthermore, we found some trends among spectral parameters that NLS1s have and BLAGNs do not have. The evolution of FWHM(H{beta}) with the luminosities of MIR and coronal lines, continuum luminosities, PAH contribution, H{beta} broad line luminosity, FWHM[OIII], and EW(H{beta}NLR) are important trends found for NLS1s. That may contribute to the insight that NLS1s are developing AGNs, growing their black holes, while their luminosities and FWHM(H{beta}) consequently grow, and that BLAGNs are mature, larger objects of slower and/or different evolution. Black hole mass is related to PAH contribution only for NLS1s, which may suggest that PAHs are more efficiently destroyed in NLS1s.