- ID:
- ivo://CDS.VizieR/J/A+A/541/A118
- Title:
- AGN-Host Galaxy Connection
- Short Name:
- J/A+A/541/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of morphological and colour analysis of X-ray detected AGN in the SXDS field. X-ray data were gathered from the XMM-Newton scientific archive, and were reduced by our team using the standard SAS procedures. The obtained catalogue of 1121 X-ray emitters was cross-matched with the publicly available optical catalogue (Furusawa et al., 2008, Cat. J/ApJS/176/1), using a cross-matched radius of 3 arcsec and obtaining 806 optical counterparts. For these objects the photometric redshifts, K-corrections, morphological, X-ray, and rest-frame colour properties were measured and analysed.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/753/104
- Title:
- AGN identifications from AKARI and Swift
- Short Name:
- J/ApJ/753/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine data from two all-sky surveys in order to study the connection between the infrared and hard X-ray (>10keV) properties for local active galactic nuclei (AGNs). The Swift Burst Alert Telescope all-sky survey provides an unbiased, flux-limited selection of hard X-ray-detected AGNs. Cross-correlating the 22 month hard X-ray survey (Tueller et al. 2010, Cat. J/ApJS/186/378) with the AKARI all-sky survey (AKARI/PSCs; Ishihara et al. 2010, Cat. II/297; Yamamura et al. 2010, Cat. II/298), we studied 158 AGNs detected by the AKARI instruments. We find a strong correlation for most AGNs between the infrared (9, 18, and 90{mu}m) and hard X-ray (14-195keV) luminosities, and quantify the correlation for various subsamples of AGNs. Partial correlation analysis confirms the intrinsic correlation after removing the redshift contribution. The correlation for radio galaxies has a slope and normalization identical to that for Seyfert 1 galaxies, implying similar hard X-ray/infrared emission processes in both. In contrast, Compton-thick (CT) sources show a large deficit in the hard X-ray band, because high gas column densities diminish even their hard X-ray luminosities. We propose two photometric diagnostics for source classification: one is an X-ray luminosity versus infrared color diagram, in which type 1 radio-loud AGNs are well isolated from the others in the sample. The other uses the X-ray versus infrared color as a useful redshift-independent indicator for identifying CT AGNs. Importantly, CT AGNs and starburst galaxies in composite systems can also be differentiated in this plane based upon their hard X-ray fluxes and dust temperatures. This diagram may be useful as a new indicator to classify objects in new and upcoming surveys such as WISE and NuSTAR.
- ID:
- ivo://CDS.VizieR/J/MNRAS/380/1467
- Title:
- AGN in supercluster A901/2
- Short Name:
- J/MNRAS/380/1467
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present XMM data for the supercluster A901/2, at z~0.17, which is combined with deep imaging and 17-band photometric redshifts (from the COMBO-17 survey), two degree field (2dF) spectra and Spitzer 24um data, to identify active galactic nuclei (AGN) in the supercluster. The 90ks XMM image contains 139 point sources, of which 11 are identified as supercluster AGN with LX(0.5-7.5keV)>1.7x10^41^erg/cm^2^/s. The host galaxies have M_R_<-20 and only two of eight sources with spectra could have been identified as AGN by the detected optical emission lines. Using a large sample of 795 supercluster galaxies, we define control samples of massive galaxies with no detected AGN. The local environments of the AGN and control samples differ at >~98 per cent significance. The AGN host galaxies lie predominantly in areas of moderate projected galaxy density and with more local blue galaxies than the control sample, with the exception of one very bright type I AGN very near the centre of a cluster. These environments are similar to, but not limited to, cluster outskirts and blue groups. Despite the large number of potential host galaxies, no AGN are found in regions with the highest galaxy density (excluding some cluster cores where emission from the intra-cluster medium obscures moderate luminosity AGN). AGN are also absent from the areas with lowest galaxy density. We conclude that the prevalence of cluster AGN is linked to their environment.
- ID:
- ivo://CDS.VizieR/J/AJ/124/3465
- Title:
- AGN in the KISS-RASS sample
- Short Name:
- J/AJ/124/3465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the X-ray properties of a volume-limited sample of optically selected emission-line galaxies. The sample is derived from a correlation between the KPNO International Spectroscopic Survey (KISS), an H{alpha}-elected objective-prism survey of active galactic nuclei (AGNs) and starbursting galaxies, and the ROSAT All-Sky Survey (RASS). After elimination of all spurious matches, we identify 18 ROSAT-detected X-ray sources within the KISS sample in the 0.1-2.4keV band.
- ID:
- ivo://CDS.VizieR/J/A+A/487/119
- Title:
- AGN in XMM-Newton Hard Bright Survey
- Short Name:
- J/A+A/487/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate here the X-ray luminosity function (XLF) of absorbed (N_H_ between 4x10^21^ and 10^24^cm^-2^) and unabsorbed (N_H_<4x10^21^cm^-2^) AGN, the fraction of absorbed AGN as a function of L_X_ (and z), the intrinsic N_H_ distribution of the AGN population, and the XLF of Compton thick (N_H>10^24^cm^-2^) AGN. To carry out this investigation, we have used the XMM-Newton Hard Bright Serendipitous Sample (HBSS), a complete sample of bright X-ray sources (f_x_>~7x10^-14^erg/cm^2^/s) at high galactic latitude (|b|>20{deg}) selected in the 4.5-7.5keV energy band. The HBSS sample is now almost completely identified (97% spectroscopic identifications) and it can be safely used for a statistical investigation. The HBSS contains 62 AGN out of which 40 are unabsorbed (or marginally absorbed; N_H_<4x10^21^cm^-2^) and 22 are absorbed (N_H_ between 4x10^21^ and ~10^24^cm^-2^).
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/640/167
- Title:
- AGNs and ULIRGs in the CDF-South
- Short Name:
- J/ApJ/640/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the nature of a sample of 92 Spitzer MIPS 24{mu}m- selected galaxies in the CDF-S, showing power-law-like emission in the Spitzer IRAC 3.6-8{mu}m bands. The main goal is to determine whether the galaxies not detected in X-rays (47% of the sample) are part of the hypothetical population of obscured AGNs not detected even in deep X-ray surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/21
- Title:
- AGNs detected by 60 month Swift/BAT survey
- Short Name:
- J/ApJ/749/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of ~2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent ~5% of AGN samples detected above 15keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to ~10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9^+4.1^_-2.9_x10^-5^/Mpc3 for objects with a de-absorbed luminosity larger than 2x10^42^erg/s. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local (<=85Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.