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1. AGN from RASS and SDSS DR5
ID:
ivo://CDS.VizieR/J/AJ/133/313
Title:
AGN from RASS and SDSS DR5
Short Name:
J/AJ/133/313
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe further results of a program aimed at yielding ~104 fully characterized optical identifications of ROSAT X-ray sources. Our program employs X-ray data from the ROSAT All Sky Survey (RASS) and both optical imaging and spectroscopic data from the Sloan Digital Sky Survey (SDSS). RASS/SDSS data from 5740deg^2^ of sky spectroscopically covered in SDSS Data Release 5 provide an expanded catalog of 7000 confirmed quasars and other active galactic nuclei (AGNs) that are probable RASS identifications. Again, in our expanded catalog the identifications as X-ray sources are statistically secure, with only a few percent of the SDSS AGNs likely to be randomly superposed on unrelated RASS X-ray sources.
2. AGNs from RXTE 3-20keV All-Sky Survey
ID:
ivo://CDS.VizieR/J/A+A/423/469
Title:
AGNs from RXTE 3-20keV All-Sky Survey
Short Name:
J/A+A/423/469
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compiled a sample of 95 AGNs serendipitously detected in the 3-20keV band at Galactic latitude |b|>10deg during the RXTE slew survey (XSS, Revnivtsev et al., Cat. <J/A+A/418/927>), and utilize it to study the statistical properties of the local population of AGNs, including the X-ray luminosity function and absorption distribution. We find that among low X-ray luminosity (LX<10^43.5^erg/s) AGNs, the ratio of absorbed (characterized by intrinsic absorption in the range 10^22^cm^-2^<NH<10^24^cm^-2^) and unabsorbed (NH<10^22^cm^-2^) objects is 2:1, while this ratio drops to less than 1:5 for higher luminosity AGNs. The summed X-ray output of AGNs with LX>10^41^erg/s estimated here is smaller than the earlier estimated total X-ray volume emissivity in the local Universe, suggesting that a comparable X-ray flux may be produced together by lower luminosity AGNs, non-active galaxies and clusters of galaxies. Finally, we present a sample of 35 AGN candidates, composed of unidentified XSS sources.
3. AGN X-Ray emission and black holes
ID:
ivo://CDS.VizieR/J/ApJS/176/355
Title:
AGN X-Ray emission and black holes
Short Name:
J/ApJS/176/355
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work we use a sample of 318 radio-quiet quasars (RQQs) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, {alpha}_ox_, and the X-ray photon index, {Gamma}_X_, on black hole mass, UV relative to Eddington luminosity, and X-ray relative to Eddington luminosity. Our sample is drawn from the literature, with X-ray data from ROSAT and Chandra, and optical data mostly from the SDSS; 153 of these sources have estimates of {Gamma}_X_ from Chandra. We estimate M_BH_ using standard estimates derived from the H{beta}, MgII, and CIV broad emission lines. To date, this is the largest study of the dependence of RQQ X-ray parameters on black hole mass and related quantities, and the first to attempt to correct for the large statistical uncertainty in the broad-line mass estimates.
4. A Hubble diagram for quasars
ID:
ivo://CDS.VizieR/J/ApJ/815/33
Title:
A Hubble diagram for quasars
Short Name:
J/ApJ/815/33
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new method to test the {Lambda}CDM cosmological model and to estimate cosmological parameters based on the nonlinear relation between the ultraviolet and X-ray luminosities of quasars. We built a data set of 1138 quasars by merging several samples from the literature with X-ray measurements at 2keV and SDSS photometry, which was used to estimate the extinction-corrected 2500{AA} flux. We obtained three main results: (1) we checked the nonlinear relation between X-ray and UV luminosities in small redshift bins up to z~6, confirming that the relation holds at all redshifts with the same slope; (2) we built a Hubble diagram for quasars up to z~6, which is well matched to that of supernovae in the common z=0-1.4 redshift interval and extends the test of the cosmological model up to z~6; and (3) we showed that this nonlinear relation is a powerful tool for estimating cosmological parameters. Using the present data and assuming a {Lambda}CDM model, we obtain {Omega}_M_=0.22_-0.08_^+0.10^ and {Omega}_{Lambda}_=0.92-0.30_^+0.18^ ({Omega}=0.28+/-0.04 and {Omega}_{Lambda}_=0.73+/-0.08 from a joint quasar-SNe fit). Much more precise measurements will be achieved with future surveys. A few thousand SDSS quasars already have serendipitous X-ray observations from Chandra or XMM-Newton, and at least 100000 quasars with UV and X-ray data will be made available by the extended ROentgen Survey with an Imaging Telescope Array all-sky survey in a few years. The Euclid, Large Synoptic Survey Telescope, and Advanced Telescope for High ENergy Astrophysics surveys will further increase the sample size to at least several hundred thousand. Our simulations show that these samples will provide tight constraints on the cosmological parameters and will allow us to test for possible deviations from the standard model with higher precision than is possible today.
5. Atlas of Quasar Energy Distributions
ID:
ivo://CDS.VizieR/J/ApJS/95/1
Title:
Atlas of Quasar Energy Distributions
Short Name:
J/ApJS/95/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an atlas of the spectral energy distributions (SEDs) of normal, non-blazar, quasars over the whole available range (radio to 10 keV X-rays) of the electromagnetic spectrum. The primary (UVSX) sample includes 47 quasars for which the spectral energy distributions include X-ray spectral indices and UV data. Of these, 29 are radio quiet, and 18 are radio loud. The SEDs are presented both in figures and in tabular form, with additional tabular material published on CD-ROM. Previously unpublished observational data for a second set of quasars excluded from the primary sample are also tabulated. The effects of host galaxy starlight contamination and foreground extinction on the UVSX sample are considered and the sample is used to investigate the range of SED properties. Of course, the properties we derive are influenced strongly by the selection effects induced by quasar discovery techniques. We derive the mean energy distribution (MED) for radio-loud and radio-quiet objects and present the bolometric corrections derived from it. We note, however, that the dispersion about this mean is large (~one decade for both the infrared and ultraviolet components when the MED is normalized at the near-infrared inflection). At least part of the dispersion in the ultraviolet may be due to time variability, but this is unlikely to be important in the infrared. The existence of such a large dispersion indicates that the MED reflects only some of the properties of quasars and so should be used only with caution.
6. 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.
7. 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.
8. 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.
9. Blazars in the Swift-BAT hard X-ray sky
ID:
ivo://CDS.VizieR/J/A+A/520/A47
Title:
Blazars in the Swift-BAT hard X-ray sky
Short Name:
J/A+A/520/A47
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a study on the blazar content in the 15-150keV map of the entire sky obtained analyzing 39 months of data collected by the BAT telescope aboard the Swift satellite. We performed a cross-correlation of the significance map, obtained with a dedicated highly efficient algorithm (Segreto et al., 2010A&A...510A..47S) for data processing and image reconstruction of the BAT survey data, with the blazar population of the Roma-BZCAT (Massaro et al., 2009, Cat. J/A+A/495/691). After corrections for source confusion and spurious detections, we found significance excesses higher than two standard deviations for 304 sources; the corresponding fraction of expected spurious associations is about 20%. We selected hard X-ray blazars according to their significance level and carried out a statistical analysis to characterise their emission properties. A sample of 121 blazars detected at a significance level sigma>3 is discussed in greater detail. The fraction of blazars with uncertain classification in this sample is considerable, more than twice with respect to the percentage obtained considering all the blazars classified in the Roma-BZCAT. We attribute the X-ray flux of the majority of selected BL Lac objects to the synchrotron emission.
10. Blazar (sub-)mm & {gamma}-ray luminosities
ID:
ivo://CDS.VizieR/J/ApJ/754/23
Title:
Blazar (sub-)mm & {gamma}-ray luminosities
Short Name:
J/ApJ/754/23
Date:
21 Oct 2021
Publisher:
CDS
Description:
The coexistence of Planck and Fermi satellites in orbit has enabled the exploration of the connection between the (sub-)millimeter and {gamma}-ray emission in a large sample of blazars. We find that the {gamma}-ray emission and the (sub-)mm luminosities are correlated over five orders of magnitude, L_{gamma}_{prop.to}L_(sub-)mm_. However, this correlation is not significant at some frequency bands when simultaneous observations are considered. The most significant statistical correlations, on the other hand, arise when observations are quasi-simultaneous within two months. Moreover, we find that sources with an approximate spectral turnover in the middle of the mm-wave regime are more likely to be strong {gamma}-ray emitters. These results suggest a physical relation between the newly injected plasma components in the jet and the high levels of {gamma}-ray emission.

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