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691. AGN models according to a UV to Mid-IR study
ID:
ivo://CDS.VizieR/J/ApJ/790/54
Title:
AGN models according to a UV to Mid-IR study
Short Name:
J/ApJ/790/54
Date:
21 Oct 2021
Publisher:
CDS
Description:
We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 deg^2^ Bootes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and mid-infrared (IRAC and MIPS) data, as well as spectroscopic redshifts for ~20,000 objects, primarily from the AGN and Galaxy Evolution Survey. We fit galaxy, active galactic nucleus (AGN), stellar, and brown dwarf templates to the observed SEDs, which yield spectral classes for the Galactic sources and photometric redshifts and galaxy/AGN luminosities for the extragalactic sources. The photometric redshift precision of the galaxy and AGN samples are {sigma}/(1 + z) = 0.040 and {sigma}/(1 + z) = 0.169, respectively, with the worst 5% outliers excluded. On the basis of the {Chi}_{nu}^2^ of the SED fit for each SED model, we are able to distinguish between Galactic and extragalactic sources for sources brighter than I = 23.5 mag. We compare the SED fits for a galaxy-only model and a galaxy-AGN model. Using known X-ray and spectroscopic AGN samples, we confirm that SED fitting can be successfully used as a method to identify large populations of AGNs, including spatially resolved AGNs with significant contributions from the host galaxy and objects with the emission line ratios of "composite" spectra. We also use our results to compare with the X-ray, mid-IR, optical color, and emission line ratio selection techniques. For an F-ratio threshold of F > 10, we find 16,266 AGN candidates brighter than I = 23.5 mag and a surface density of ~1900 AGN deg^-2^.
692. AGN neutrino source candidates
ID:
ivo://CDS.VizieR/J/other/APh/26.282
Title:
AGN neutrino source candidates
Short Name:
J/other/APh/26.2
Date:
21 Oct 2021
Publisher:
CDS
Description:
The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high-energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.
693. AGN observations obtained at FAI
ID:
ivo://fai.kz/fai_agn/q/i
Title:
AGN observations obtained at FAI
Short Name:
fai_agn siap
Date:
10 Oct 2023 11:48:20
Publisher:
Fesenkov Astrophysical Institute
Description:
The database of Active Galactic Nuclea (AGN) photometrical observations obtained on defferent telescopes at Fesenkov Astrophysical Institute, Almaty, Kazakhstan since 2016. Observations were carried out in the optical range.
694. 4 AGN optical spectra
ID:
ivo://CDS.VizieR/J/A+A/596/A64
Title:
4 AGN optical spectra
Short Name:
J/A+A/596/A64
Date:
21 Oct 2021
Publisher:
CDS
Description:
Intermediate-Mass Black Holes (IMBHs) are thought to be the seeds of early Supermassive Black Holes (SMBHs). While >~100 IMBH and small SMBH candidates have been identified in recent years, few have been robustly confirmed to date, leaving their number density in considerable doubt. Placing firmer constraints both on the methods used to identify and confirm IMBHs/SMBHs, as well as characterizing the range of host environments that IMBHs/SMBHs likely inhabit is therefore of considerable interest and importance. Additionally, finding significant numbers of IMBHs in metal-poor systems would be particularly intriguing, since such systems may represent local analogs of primordial galaxies, and therefore could provide clues of early accretion processes. Here we study in detail several candidate Active Galactic Nuclei (AGN) found in metal-poor hosts. We utilize new X-ray and optical observations to characterize these metal-poor AGN candidates and compare them against known AGN luminosity relations and well-characterized IMBH/SMBH samples.
695. AGN Opt/IR properties in Lockman Hole
ID:
ivo://CDS.VizieR/J/A+A/529/A135
Title:
AGN Opt/IR properties in Lockman Hole
Short Name:
J/A+A/529/A135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the observed-frame optical, near-, and mid-infrared properties of X-ray-selected active galactic nuclei (AGN) in the Lockman Hole. Using a likelihood ratio method on optical, near-infrared or mid-infrared catalogues, we assigned counterparts to 401 out of the 409 X-ray sources of the XMM-Newton catalogue. Accurate photometry was collected for all the sources from U to 24um. We used X-ray and optical criteria to remove any normal galaxies, galactic stars, or X-ray clusters among them and studied the multi-wavelength properties of the remaining 377 AGN. We used a mid-IR colour-colour selection to understand the AGN contribution to the optical and infrared emission.
696. AGN pairs from SDSS-DR7. I.
ID:
ivo://CDS.VizieR/J/ApJ/737/101
Title:
AGN pairs from SDSS-DR7. I.
Short Name:
J/ApJ/737/101
Date:
21 Oct 2021
Publisher:
CDS
Description:
Galaxy-galaxy mergers and close interactions have long been regarded as a viable mechanism for channeling gas toward the central supermassive black holes (SMBHs) of galaxies which are triggered as active galactic nuclei (AGNs). AGN pairs, in which the central SMBHs of a galaxy merger are both active, are expected to be common from such events. We conduct a systematic study of 1286 AGN pairs at \bar{z}~0.1 with line-of-sight velocity offsets {Delta}v<600km/s and projected separations r_p_<100h^-1^_70_kpc, selected from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS, Cat. II/294). This AGN pair sample was drawn from 138070 AGNs optically identified based on diagnostic emission line ratios and/or line widths. The fraction of AGN pairs with 5h^-1^_70_kpc<~r_p_<100h^-1^_70_kpc among all spectroscopically selected AGNs at 0.02<z<0.16 is 3.6% after correcting for SDSS spectroscopic incompleteness; ~30% of these pairs show morphological tidal features in their SDSS images, and the fraction becomes >~80% for pairs with the brightest nuclei.
697. AGN photometry. II. A catalog from the CFHTLS
ID:
ivo://CDS.VizieR/J/AJ/146/87
Title:
AGN photometry. II. A catalog from the CFHTLS
Short Name:
J/AJ/146/87
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the second paper of the series Detecting Active Galactic Nuclei Using Multi-filter Imaging Data. In this paper we review shapelets, an image manipulation algorithm, which we employ to adjust the point-spread function (PSF) of galaxy images. This technique is used to ensure the image in each filter has the same and sharpest PSF, which is the preferred condition for detecting AGNs using multi-filter imaging data as we demonstrated in Paper I of this series. We apply shapelets on Canada-France-Hawaii Telescope Legacy Survey Wide Survey ugriz images. Photometric parameters such as effective radii, integrated fluxes within certain radii, and color gradients are measured on the shapelets-reconstructed images. These parameters are used by artificial neural networks (ANNs) which yield: photometric redshift with an rms of 0.026 and a regression R-value of 0.92; galaxy morphological types with an uncertainty less than 2 T types for z<=0.1; and identification of galaxies as AGNs with 70% confidence, star-forming/starburst (SF/SB) galaxies with 90% confidence, and passive galaxies with 70% confidence for z<=0.1. The incorporation of ANNs provides a more reliable technique for identifying AGN or SF/SB candidates, which could be very useful for large-scale multi-filter optical surveys that also include a modest set of spectroscopic data sufficient to train neural networks.
698. AGN/pulsar distinction for 2FGL sources
ID:
ivo://CDS.VizieR/J/MNRAS/424/L64
Title:
AGN/pulsar distinction for 2FGL sources
Short Name:
J/MNRAS/424/L64
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dark matter annihilation signals coming from Galactic subhaloes may account for a small fraction of unassociated point sources detected in the second Fermi-LAT Catalogue (2FGL). To investigate this possibility, we present SIBYL, a Random Forest classifier that offers predictions on class memberships for unassociated Fermi-LAT sources at high Galactic latitudes using gamma-ray features extracted from the 2FGL. SIBYL generates a large ensemble of classification trees that are trained to vote on whether a particular object is an active galactic nucleus (AGN) or a pulsar. After training on a list of 908 identified/associated 2FGL sources, SIBYL reaches individual accuracy rates of up to 97.7 per cent for AGNs and 96.5 per cent for pulsars. Predictions for the 269 unassociated 2FGL sources at |b|>=10{deg} suggest that 216 are potential AGNs and 16 are potential pulsars (with majority votes greater than 70 per cent). The remaining 37 objects are inconclusive, but none is an extreme outlier. These results could guide future quests for dark matter Galactic subhaloes.
699. AGN sample in the northern XMM-XXL field
ID:
ivo://CDS.VizieR/J/MNRAS/459/1602
Title:
AGN sample in the northern XMM-XXL field
Short Name:
J/MNRAS/459/1602
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper we describe and publicly release a catalogue consisting of 8445 point-like X-ray sources detected in the XMM-XXL north survey. For the 2512 AGN which have reliable spectroscopy from SDSS-III/BOSS, we present the X-ray spectral fitting which has been computed with a Bayesian approach. We have also applied an X-ray spectral stacking method to different sub-samples, selected on the basis of the AGN physical properties (L_2-10keV_, z, M_BH_, {lambda}_Edd_ and N_H_). We confirm the well-known Iwasawa-Taniguchi effect in our luminosity-redshift sub-samples, and argue that such an effect is due to a decrease in the covering factor of a distant obscuring 'torus' with increasing X-ray luminosity. By comparing the distribution of the reflection fraction, the ratio of the normalization of the reflected component to the direct radiation, we find that the low-luminosity, low-redshift sub-sample had systematically higher reflection fraction values than the high-redshift, high-luminosity one. On the other hand, no significant difference is found between samples having similar luminosity but different redshift, suggesting that the structure of the torus does not evolve strongly with redshift. Contrary to previous works, we do not find evidence for an increasing photon index at high Eddington ratio. This may be an indication that the structure of the accretion disc changes as the Eddington ratio approaches unity. Comparing our X-ray spectral analysis results with the optical spectral classification, we find that ~20 per cent of optical type-1 AGN show an X-ray absorbing column density higher than 10^21.5^cm^-2^, and about 50 per cent of type-2 AGN have an X-ray absorbing column density less than 10^21.5^cm^-2^. We suggest that the excess X-ray absorption shown in the high-luminosity optical type-1 AGN can be due to small-scale dust-free gas within (or close to) the broad-line region, while in the low-luminosity ones it can be due to a clumpy torus with a large covering factor.
700. AGNs and host galaxies information
ID:
ivo://CDS.VizieR/J/AJ/131/84
Title:
AGNs and host galaxies information
Short Name:
J/AJ/131/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad-line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification.

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