- ID:
- ivo://CDS.VizieR/J/ApJS/215/14
- Title:
- WISE candidate {gamma}-ray blazar radio sources
- Short Name:
- J/ApJS/215/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of radio-loud candidate {gamma}-ray emitting blazars with WISE mid-infrared colors similar to the colors of confirmed {gamma}-ray blazars. The catalog is assembled from WISE sources detected in all four WISE filters, with colors compatible with the three-dimensional locus of the WISE {gamma}-ray emitting blazars, and which can be spatially cross-matched with radio sources from one of the three radio surveys: NVSS, FIRST, and/or SUMSS. Our initial WISE selection uses a slightly modified version of previously successful algorithms. We then select only the radio-loud sources using a measure of the radio-to-IR flux, the q_22_parameter, which is analogous to the q_24_ parameter known in the literature but which instead uses the WISE band-four flux at 22{mu}m. Our final catalog contains 7855 sources classified as BL Lacs, FSRQs, or mixed candidate blazars; 1295 of these sources can be spatially re-associated as confirmed blazars. We describe the properties of the final catalog of WISE blazar-like radio-loud sources and consider possible contaminants. Finally, we discuss why this large catalog of candidate {gamma}-ray emitting blazars represents a new and useful resource to address the problem of finding low-energy counterparts to currently unidentified high-energy sources.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/805/90
- Title:
- WISE ELIRGs and comparison with QSOs
- Short Name:
- J/ApJ/805/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 20 Wide-field Infrared Survey Explorer (WISE)-selected galaxies with bolometric luminosities L_bol_>10^14^L_{sun}_, including five with infrared luminosities L_IR_{equiv}L_(rest8-1000{mu}m)_>10^14^L_{sun}_. These "extremely luminous infrared galaxies", or ELIRGs, were discovered using the "W1W2-dropout" selection criteria which requires marginal or non-detections at 3.4 and 4.6{mu}m (W1 and W2, respectively) but strong detections at 12 and 22{mu}m in the WISE survey. Their spectral energy distributions are dominated by emission at rest-frame 4-10{mu}m, suggesting that hot dust with T_d_~450K is responsible for the high luminosities. These galaxies are likely powered by highly obscured active galactic nuclei (AGNs), and there is no evidence suggesting these systems are beamed or lensed. We compare this WISE-selected sample with 116 optically selected quasars that reach the same L_bol_ level, corresponding to the most luminous unobscured quasars in the literature. We find that the rest-frame 5.8 and 7.8{mu}m luminosities of the WISE-selected ELIRGs can be 30%-80% higher than that of the unobscured quasars. The existence of AGNs with L_bol_>10^14^L_{sun}_ at z>3 suggests that these supermassive black holes are born with large mass, or have very rapid mass assembly. For black hole seed masses ~10^3^M_{sun}_, either sustained super-Eddington accretion is needed, or the radiative efficiency must be <15%, implying a black hole with slow spin, possibly due to chaotic accretion.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/68
- Title:
- WISE IR colors of gamma-ray blazars
- Short Name:
- J/ApJ/748/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Blazars constitute the most enigmatic class of extragalactic {gamma}-ray sources, and their observational features have been ascribed to a relativistic jet closely aligned to the line of sight. They are generally divided in two main classes: the BL Lac objects (BL Lacs) and the flat-spectrum radio quasars (FSRQs). In the case of BL Lacs the double-bumped spectral energy distribution (SED) is generally described by the synchrotron self-Compton (SSC) emission, while for the FSRQs it is interpreted as due to external Compton (EC) emission. Recently, we showed that in the [3.4]-[4.6]-[12]{mu}m color-color diagram the blazar population covers a distinct region (i.e., the WISE blazar Strip (WBS)) clearly separated from the other extragalactic sources that are dominated by thermal emission. In this paper, we investigate the relation between the infrared and {gamma}-ray emission for a subset of confirmed blazars from the literature, associated with Fermi sources, for which WISE archival observations are available. This sample is a proper subset of the sample of sources used previously, and the availability of Fermi data is critical to constrain the models on the emission mechanisms for the blazars.
- ID:
- ivo://CDS.VizieR/J/A+A/436/799
- Title:
- X- and gamma-ray fluxes of {gamma}-ray-loud blazars
- Short Name:
- J/A+A/436/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined the basic parameters, such as the central black hole mass (M), the boosting factor (or Doppler factor) ({delta}) the propagation angle ({Phi}) and the distance along the axis to the site of {gamma}-ray production (d) for 23 {gamma}-ray-loud blazars using their available variability timescales.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/125
- Title:
- X and {gamma} spectral indexes of Fermi blazars
- Short Name:
- J/ApJ/761/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, a sample of 451 blazars (193 flat spectrum radio quasars (FSRQs), 258 BL Lacertae objects) with corresponding X-ray and Fermi {gamma}-ray data is compiled to investigate the correlation both between the X-ray spectral index and the {gamma}-ray spectral index and between the spectral index and the luminosity, and to compare the spectral indexes {alpha}_X_, {alpha}_{gamma}_, {alpha}_X{gamma}_, and {alpha}_{gamma}X{gamma}_ for different subclasses. We also investigated the correlation between the X-ray and the {gamma}-ray luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/15
- Title:
- Xinglong spectra of two changing-look SDSS AGNs
- Short Name:
- J/ApJ/887/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a spectroscopic identification of two new changing-look active galactic nuclei (CL-AGNs): SDSSJ104705.16+544405.8 and SDSSJ120447.91+170256.8, both with a "turn-off" type transition from type-1 to type-1.8/1.9. The identification is arrived at through a follow-up spectroscopic observation of the five CL-AGNs candidates that are extracted from the sample recently released in MacLeod+ (2019, J/ApJ/874/8). The candidates are extracted by the authors from the Sloan Digit Sky Survey Data Release 7, and are spectroscopically confirmed quasars with large amplitude variability. By compiling a sample of 26 previously identified CL-AGNs, we confirm the claim by MacLeod+ that CL-AGNs tend to be biased against a low Eddington ratio, and identify an overlap between the CL-AGNs at their dim state and the so-called intermediate-type AGNs. The overlap implies that there two populations of the intermediate-type AGNs with different origins. One is due to the torus orientation effect, and the other to the intrinsic change of the accretion rate of the central supermassive black holes.
- ID:
- ivo://CDS.VizieR/J/A+A/439/413
- Title:
- XMDS/VVDS 4{sigma} catalogue
- Short Name:
- J/A+A/439/413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 286 X-ray sources with their optical identification taken from the XMDS survey (using the XMM-Newton EPIC instrument). This first version is limited to sources detected at 4{sigma} at least in one energy band, AND falling in the area covered by the optical VVDS survey.
1038. XMM-COSMOS Type 1 AGNs
- ID:
- ivo://CDS.VizieR/J/A+A/512/A34
- Title:
- XMM-COSMOS Type 1 AGNs
- Short Name:
- J/A+A/512/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the X-ray to optical properties of a sample of 545 X-ray selected Type 1 AGN, from the XMM-COSMOS survey, over a wide range of redshifts (0.04<z<4.25) and X-ray luminosities (40.6<=LogL[2-10]keV<=45.3). About 60% of them are spectroscopically identified Type 1 AGN, while the others have a reliable photometric redshift and are classified as Type 1 AGN on the basis of their multi-band Spectral Energy Distributions. We discuss the relationship between UV and X-ray luminosity, as parameterized by the alpha_ox_ spectral slope, and its dependence on redshift and luminosity.
- ID:
- ivo://CDS.VizieR/J/PAZh/42/313
- Title:
- 3XMM-DR4 QSO candidates at 3<z<5.5
- Short Name:
- J/PAZh/42/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of quasar candidates at redshifts 3<z<5.5 is presented. These candidates have been selected among X-ray sources in the XMM-Newton Serendipitous Source Catalog (3XMM-DR4) in the 0.5-2keV band, located at high galactic latitudes |b|>20deg in the Sloan Digital Sky Survey (SDSS) area. The total overlapping area is about 300 sq. deg. The SDSS, 2MASS and WISE photometric catalogs were used. Only SDSS point sources were considered. X-ray sources having an optical counterpart with magnitude error in SDSS z band of less than 0.2 and color i-z<0.6 were chosen. Their photometric redshifts were determined with the EAZY code using a library of spectral templates. A sample of quasar candidates with photometric redshifts in the range 2.75<z<5.5 has been composed. Objects whose spectral energy distributions are better described by stellar templates have been excluded. The selection completeness of known quasars is about 80%. The normalized median absolute deviation of the differences between the photometric and spectroscopic redshifts of known quasars is 0.07 (with 9% outliers). The sky density of quasar candidates in our sample is 1.5 times that of the spectroscopic SDSS sample in the same fields. Follow-up spectroscopy should clarify the purity of the sample.
- ID:
- ivo://CDS.VizieR/J/PAZh/45/464
- Title:
- 3XMM-DR4 QSO candidates optical spectroscopy
- Short Name:
- J/PAZh/45/464
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the results of optical spectroscopy for 58 quasar candidates at photometric redshifts z>~3, 57 of which enter into the Khorunzhev et al. (2016, Cat. J/PAZh/42/313) catalog (K16). This is a catalog of quasar candidates and known type 1 quasars selected among the X-ray sources of the 3XMM-DR4 catalog of the XMM-Newton serendipitous survey. At first we have performed spectroscopy for a quasi-random sample of 19 candidates at the 1.6-m AZT-33IK telescope of the Sayan Solar Observatory and the 6-m BTA telescope of the Special Astrophysical Observatory (SAO RAS). Then we have continued the observation for 39 X-ray bright candidates that could be used for the X-ray luminosity function construction (see Khorunzhev et al. 2018AstL...44..500K). The spectra at AZT-33IK were taken with the new low- and medium-resolution ADAM spectrograph that was produced and installed on the telescope in 2015. One of the most distant (z=5.08) optically bright (i=21) quasars ever detected in X-ray surveys has been discovered.
