- ID:
- ivo://CDS.VizieR/J/A+A/655/A48
- Title:
- XMM-Newton catalogue of BL Lacs
- Short Name:
- J/A+A/655/A48
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the results of the XMM-Newton catalogue of BL Lacs. X-ray and optical UV properties is presented based on the cross-correlation with the 1151 BL Lacs listed in the 5th edition of the Roma-BZCAT. The X-ray counterparts to these objects are searched in the field of view of all pointed observations in the XMM-Newton archive over nearly 20 years of mission. The cross-correlation yields a total of 310 XMM-Newton fields which correspond to 103 different BL Lacs. Data from the three EPIC cameras (X-ray) and OM (optical/UV) are homogeneously analysed using the XMM-Newton SAS software. Images, light curves and spectral products are produced for those BL Lacs detected in any of the three EPIC cameras. Two different phenomenological models, log parabola and power law, with different variations of the absorbing column density, are tested and their parameters extracted. Time variability information is derived from the light curves following well established statistical methods, and we quantify variability through statistical indicators. OM magnitudes and fluxes are computed when available.
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- ID:
- ivo://CDS.VizieR/J/ApJS/217/21
- Title:
- XMM-Newton survey of local OVII absorbers
- Short Name:
- J/ApJS/217/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Highly ionized, z=0 metal absorption lines detected in the X-ray spectra of background active galactic nuclei (AGNs) provide an effective method to probe the hot (T~10^6^K) gas and its metal content in and around the Milky Way. We present an all-sky survey of the K_{alpha}_ transition of the local OVII absorption lines obtained by Voigt-profile fitting archival XMM-Newton observations. A total of 43 AGNs were selected, among which 12 are BL Lac-type AGNs, and the rest are Seyfert 1 galaxies. At above the 3{sigma} level the local OVII absorption lines were detected in 21 AGNs, among which 7 were newly discovered in this work. The sky covering fraction, defined as the ratio between the number of detections and the sample size, increases from about 40% for all targets to 100% for the brightest targets, suggesting a uniform distribution of the OVII absorbers. We correlate the line equivalent width with the Galactic coordinates and do not find any strong correlations between these quantities. Some AGNs have warm absorbers that may complicate the analysis of the local X-ray absorber since the recession velocity can be compensated by the outflow velocity, especially for nearby targets. We discuss the potential impact of warm absorbers on our analysis.
- ID:
- ivo://CDS.VizieR/J/ApJ/747/10
- Title:
- X-ray and multiwavelength properties of 11 WLQs
- Short Name:
- J/ApJ/747/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z=0.4-2.5. Our sample was selected from the Plotkin et al. catalog (2010, Cat. J/AJ/139/390) of radio-quiet, weak-featured active galactic nuclei (AGNs). The distribution of relative X-ray brightness for our low-redshift weak-line quasar (WLQ) candidates is significantly different from that of typical radio-quiet quasars, having an excess of X-ray weak sources, but it is consistent with that of high-redshift WLQs. Over half of the low-redshift WLQ candidates are X-ray weak by a factor of >~5, compared to a typical SDSS quasar with similar UV/optical luminosity. These X-ray weak sources generally show similar UV emission-line properties to those of the X-ray weak quasar PHL 1811 (weak and blueshifted high-ionization lines, weak semiforbidden lines, and strong UV Fe emission); they may belong to the notable class of PHL 1811 analogs. The average X-ray spectrum of these sources is somewhat harder than that of typical radio-quiet quasars.
- ID:
- ivo://CDS.VizieR/J/ApJS/226/20
- Title:
- X-ray, opt. & radio SEDs of Fermi blazars
- Short Name:
- J/ApJS/226/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, multiwavelength data are compiled for a sample of 1425 Fermi blazars to calculate their spectral energy distributions (SEDs). A parabolic function, log({nu}F_{nu}_)=P_1_(log{nu}-P_2_)^2^+P_3_, is used for SED fitting. Synchrotron peak frequency (log{nu}_p_), spectral curvature (P_1_), peak flux ({nu}_p_F_{nu}p_), and integrated flux ({nu}F_{nu}_) are successfully obtained for 1392 blazars (461 flat-spectrum radio quasars [FSRQs], 620 BL Lacs [BLs], and 311 blazars of uncertain type [BCUs]; 999 sources have known redshifts). Monochromatic luminosity at radio 1.4GHz, optical R band, X-ray at 1keV and {gamma}-ray at 1GeV, peak luminosity, integrated luminosity, and effective spectral indices of radio to optical ({alpha}_RO_) and optical to X-ray ({alpha}_OX_) are calculated. The "Bayesian classification" is employed to log{nu}_p_ in the rest frame for 999 blazars with available redshift, and the results show that three components are enough to fit the log{nu}_p_ distribution; there is no ultra-high peaked subclass. Based on the three components, the subclasses of blazars using the acronyms of Abdo+ (2010, J/ApJ/716/30) are classified, and some mutual correlations are also studied.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/29
- Title:
- X-ray polarization predictions in blazars
- Short Name:
- J/ApJ/880/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- X-ray polarization should provide new probes of magnetic field geometry and acceleration physics near the base of blazar jets, but near-future missions will have limited sensitivity. We thus use existing lower energy data and X-ray variability measurements in the context of a basic synchro-Compton model to predict the X-ray polarization level and the probability of detection success for individual sources, listing the most attractive candidates for an Imaging X-ray Polarimetry Explorer campaign. We find that, as expected, several high-peak blazars such as Mrk 421 can be easily measured in 100ks exposures. Most low-peak sources should only be accessible to triggered campaigns during bright flares. Surprisingly, a few intermediate peak sources can have anomalously high X-ray polarization and thus are attractive targets.
- ID:
- ivo://CDS.VizieR/J/A+A/434/385
- Title:
- X-ray/radio data of high energy peaked BL Lacs
- Short Name:
- J/A+A/434/385
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fully identified complete sample including 150 extreme HBL BL Lacs is presented in Table 1 where we give the source name built with the catalog identification code SHBL (where S stands for "Sedentary" survey and HBL for High energy peaked BL Lacs) and the arcsecond precision optical coordinates of the source taken from the APM and COSMOS on-line services; we give also the RASS name, the X-ray flux (0.1-2.4keV), the radio flux (20cm, from the NVSS survey), and the optical apparent V magnitude (from APM and COSMOS) respectively; we give the redshift when available and the reference for the optical identification. In Table 2 we report properties for five bright elliptical galaxies/low luminosity HBLs in the original sample of high fX/fr sources of Paper I (Giommi et al., 1999MNRAS.310..465G). In Table 3 the 19 rejected emission line AGNs together with their properties are presented.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A126
- Title:
- XShooter spectrum of 4 BL Lacs
- Short Name:
- J/A+A/570/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine the redshift (or stringent lower limits) of a number of bright BL Lacs objects. We secured optical and near-infrared medium resolution spectra of four bright BL Lac objects of unknown redshift using the spectrograph X-Shooter at the ESO-VLT. In spite of the high quality of the spectra and the extended spectral range of the observations, we have not detected intrisic spectral features for these sources. However, we are able to provide strigent lower limits to their redshift. In particular, for the two TeV sources PG 1553+113 and H 1722+119, we infer z>0.30 and z>0.35 respectively. We also detect an intervening CaII absorption doublet in the spectrum of MH 2136-428 that is ascribed to the the halo of a nearby giant elliptical galaxy at a projected distance of ~100kpc. Under the hypothesis that all BL Lacs are hosted by a luminous bulge dominated galaxies, the presently spectroscopic observations of bright BL Lacs indicate that these objects are likely sources with extremely beamed nuclear emission. We present simulations to show under which circumstances it is possible to probe this hypothesis from the detection of very weak absorptions using the next generation of extremely large optical telescopes.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A6
- Title:
- 12Y-MST and 12Y-MSTw Catalogues
- Short Name:
- J/A+A/652/A6
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present an updated version catalogue of gamma-ray source candidates, 12Y-MST, selected using the Minimum Spanning Tree (MST) algorithm on the 12-years Fermi/LAT sky (Pass 8) at energies higher than 10GeV. The high energy sky at absolute Galactic latitudes above 20 degrees has been investigated using rather restrictive selection criteria, resulting in a total sample of 1664 photon clusters, or candidate sources. Of these, 230 are new detections, i.e., candidate sources without any association in other gamma-ray catalogues. A large fraction of them have interesting counterparts, most likely blazars. In this paper the main results on the catalogue selection and search of counterparts are described. We also present an additional sample of 224 candidate sources (12Y-MSTw), which are clusters extracted applying weaker selection criteria: about 57% of them have not been reported in other catalogues.
289. 9Y-MST Catalogue
- ID:
- ivo://CDS.VizieR/J/A+A/619/A23
- Title:
- 9Y-MST Catalogue
- Short Name:
- J/A+A/619/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a catalogue of gamma-ray source candidates selected using the minimum spanning tree (MST) algorithm on the nine year Fermi-LAT sky (Pass 8) at energies higher than 10GeV. The extragalactic sky at absolute Galactic latitudes above 20{deg} has been investigated using rather restrictive selection criteria, resulting in a total sample of 1342 sources. Of these, 249 are new detections that have not been previously associated with gamma-ray catalogues. A large portion of these candidates have interesting counterparts, which are most likely blazars. In this paper, we report the main results of the catalogue selection and search of counterparts.
- ID:
- ivo://CDS.VizieR/J/ApJ/896/L19
- Title:
- 16yr LC of TXS 0506+056 from MASTER networks
- Short Name:
- J/ApJ/896/L19
- Date:
- 07 Dec 2021
- Publisher:
- CDS
- Description:
- We present the earliest astronomical observation of a high-energy neutrino error box of which the variability was discovered after high-energy-neutrino detection. The one robotic telescope of the MASTER global international networks automatically imaged the error box of the very high-energy-neutrino event IceCube-170922A. Observations were carried out in minutes after the IceCube-170922A neutrino event was detected by the IceCube observatory at the South Pole. MASTER found the blazar TXS 0506+056 to be in the off-state after one minute and then switched to the on-state no later than two hours after the event. The effect is observed at a 50{sigma} significance level. We also present own a unique 16yr light curve of blazar TXS 0506+056 (518 data set).