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Using a simple unification model for AGN, with a fixed ratio of obscured to unobscured AGN of 3:1, we explain the X-ray, optical and infrared properties of the X-ray sources in the GOODS fields. That is, the GOODS data are consistent with the existence of a large population of obscured AGN out to high redshifts. About half of these are so obscured that they are missed even by hard X-ray observations, and are detected only in deep infrared observations. The previously reported decreasing trend of obscured to total AGN ratio with increasing X-ray luminosity can be explained entirely as a selection effect.

Using the Far Ultraviolet Spectroscopic Explorer (FUSE) we have obtained 87 spectra of 57 low-redshift (z<0.15) active galactic nuclei (AGN). This sample comprises 53 Type 1 AGN and 4 Type 2. All the Type 1 objects show broad O VI 1034 emission; two of the Type 2s show narrow O VI emission. In addition to O VI, we also identify emission lines due to C III 977, N III 991, S IV 1062,1072, and He II 1085 in many of the Type-1 AGN. Of the Type 1 objects, 30 show intrinsic absorption by the O VI 1032,1038 doublet. Most of these intrinsic absorption systems show multiple components with intrinsic widths of 100 km/s spread over a blue-shifted velocity range of less than 1000 km/s. Galaxies in our sample with existing X-ray or longer wavelength UV observations also show C IV absorption and evidence of a soft X-ray warm absorber. In some cases, a UV absorption component has physical properties similar to the X-ray absorbing gas, but in others there is no clear physical correspondence between the UV and X-ray absorbing components. Models in which a thermally driven wind evaporates material from the obscuring torus naturally produce such inhomogeneous flows.

We present the results of the analysis of the first 9 months of data of the Swift BAT survey of AGNs in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGNs) of 130 objects detected at | b| > 15° and with significance >4.8 σ. One source remains unidentified. These same X-ray data have allowed measurement of the X-ray properties of the objects. We fit a power law to the log N–log S distribution, and find the slope to be 1.42 ± 0.14. Characterizing the differential luminosity function data as a broken power law, we find a break luminosity log L * (erg s −1 ) = 43.85 ± 0.26, a low-luminosity power law slope a = 0.84 + 0.16 −0.22 , and a high-luminosity power law slope b = 2.55 + 0.43 −0.30 , similar to the values that have been reported based on INTEGRAL data. We obtain a mean photon index 1.98 in the 14-195 keV band, with an rms spread of 0.27. Integration of our luminosity function gives a local volume density of AGNs above 10 41 erg s −1 of 2.4 × 10 −3 Mpc −3 , which is about 10% of the total luminous local galaxy density above M * = − 19.75. We have obtained X-ray spectra from the literature and from Swift XRT follow-up observations. These show that the distribution of log n H is essentially flat from n H = 10 20 to 10 24 cm −2 , with 50% of the objects having column densities of less than 10 22 cm −2 . BAT Seyfert galaxies have a median redshift of 0.03, a maximum log luminosity of 45.1, and approximately half have log n H > 22.

Using the known numbers and evolution of unobscured AGN, and assuming that there is a large number of corresponding obscured AGN -- as expected if AGN unification is correct -- we predict the infrared number counts of AGN. These agree well with the observed GOODS Spitzer data at 3.6, 8 and 24 $μ$m, provided that the dust content of the obscuring torus is $\sim 2$x less than assumed. This strongly supports the AGN unification picture, and implies a large population of infrared bright obscured AGN at all redshifts and luminosities.

Infrared selection is a potentially powerful way to identify heavily obscured AGNs missed in even the deepest X-ray surveys. Using a 24 μm-selected sample in GOODS-S, we test the reliability and completeness of three infrared AGN selection methods: (1) IRAC color-color selection, (2) IRAC power-law selection, and (3) IR-excess selection; we also evaluate a number of IR-excess approaches. We find that the vast majority of non-power-law IRAC color-selected AGN candidates in GOODS-S have colors consistent with those of star-forming galaxies. Contamination by star-forming galaxies is most prevalent at low 24 μm flux densities (~100 μJy) and high redshifts ( z ∼ 2), but the fraction of potential contaminants is still high (~50%) at 500 μJy, the highest flux density probed reliably by our survey. AGN candidates selected via a simple, physically motivated power-law criterion ("power-law galaxies," or PLGs), however, appear to be reliable. We confirm that the IR-excess methods successfully identify a number of AGNs, but we also find that such samples may be significantly contaminated by star-forming galaxies. Adding only the secure Spitzer -selected PLG, color-selected, IR-excess, and radio/IR-selected AGN candidates to the deepest X-ray-selected AGN samples directly increases the number of known X-ray AGNs (84) by 54%-77%, and implies an increase to the number of 24 μm-detected AGNs of 71%-94%. Finally, we show that the fraction of MIR sources dominated by an AGN decreases with decreasing MIR flux density, but only down to f 24 μ m = 300 μJy. Below this limit, the AGN fraction levels out, indicating that a nonnegligible fraction (~10%) of faint 24 μm sources (the majority of which are missed in the X-ray) are powered not by star formation, but by the central engine. The fraction of all AGNs (regardless of their MIR properties) exceeds 15% at all 24 μm flux densities.

We present analysis of spectral energy distributions (SEDs) from mid-infrared through X-ray of a sample of 420 hard X-ray selected, z-band and Spitzer/IRAC detected active galactic nuclei (AGN) and AGN candidates from the GOODS multiwavelength survey. We fit local empirical SED templates of both normal and active galaxies to the rest-frame luminosities calculated from spectroscopic (where available) and photometric redshifts. The majority of the optically stellar-dominated (with early-type galaxy fits) sources are moderately luminous (L_X,2-10 keV ~ 10^43 erg/s) hard X-ray sources with high X-ray hardness ratios (HR > 0.2), high MIR luminosities and red MIR colors in excess of a typical stellar dominated elliptical galaxy. These sources likely harbor heavily obscured (though Compton-thin) AGN. The observed ratio of obscured to unobscured AGN has an integrated mean of ~3.4:1 but declines with increasing redshift. This effect has been explained by Treister et al. (2004) as an observational bias triggered by the lack of spectroscopic redshifts at R > 24 which are predominantly higher redshift obscured sources.

Abstract We present two large catalogs of active galactic nucleus (AGN) candidates identified across 30,093 deg 2 of extragalactic sky from the Wide-field Infrared Survey Explorer’s AllWISE Data Release. Both catalogs are selected purely using the Wide-field Infrared Survey Explorer ( WISE ) W1 and W2 bands. The R90 catalog consists of 4,543,530 AGN candidates with 90% reliability, while the C75 catalog consists of 20,907,127 AGN candidates with 75% completeness. These reliability and completeness figures were determined from a detailed analysis of UV- to near-IR spectral energy distributions of sources in the 9 deg 2 Boötes field. The AGN selection criteria are based on those of Assef et al. (2013) recalibrated to the AllWISE data release. We provide a detailed discussion of potential artifacts and excise portions of the sky close to the Galactic Center, Galactic Plane, nearby galaxies, and other expected contaminating sources. These catalogs are expected to enable a broad range of science, and we present a few illustrative cases. From the R90 sample, we identify 45 highly variable AGNs lacking radio counterparts in the FIRST survey. One of these sources, WISEA J142846.71+172353.1, is a changing-look quasar at z = 0.104, which has changed from having broad H α to being a narrow-lined AGN. We characterize our catalogs by comparing them to large, wide-area AGN catalogs in the literature. We identify four ROSAT X-ray sources that are each matched to three WISE -selected AGNs in the R90 sample within 30″. Spectroscopy reveals that one of these systems, 2RXS J150158.6+691029, consists of a triplet of quasars at z = 1.133 ± 0.004, suggestive of a rich group or forming galaxy cluster.

KaVA (KVN and VERA Array) is a new combined VLBI array with KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). First, we briefly review the imaging capabilities of KaVA array which actually achieves more than three times better dynamic range than that achieved by VERA alone. The KaVA images clearly show detailed structures of extended radio jets in AGNs. Next, we represent the key science program to be led by KaVA AGN sub working group. We will conduct the monitoring observations of Sgr A* and M87 because of the largeness of their central super-massive black hole angular sizes. The main science goals of the program are (i) testing magnetically-driven-jet paradigm by mapping velocity fields of the M87 jet, and (ii) obtaining tight constraints on physical properties of radio emitting region in Sgr A*.

Abstract We present the first catalog and data release of the Swift-BAT AGN Spectroscopic Survey. We analyze optical spectra of the majority of the detected AGNs (77%, 642/836)based on their 14–195 keV emission in the 70-month Swift-BAT all-sky catalog. This includes redshift determination, absorption and emission-line measurements, and black hole mass and accretion rate estimates for the majority of obscured and unobscured AGNs (74%, 473/642), with 340 measured for the first time. With ∼90% of sources at , the survey represents a significant advance in the census of hard X-ray-selected AGNs in the local universe. In this first catalog paper, we describe the spectroscopic observations and data sets, and our initial spectral analysis. The FWHMs of the emission lines show broad agreement with the X-ray obscuration (∼94%), such that Sy 1–1.8 have cm−2, and Seyfert 2 have cm−2. Seyfert 1.9, however, show a range of column densities. Compared to narrow-line AGNs in the SDSS, the X-ray-selected AGNs have a larger fraction of dusty host galaxies ( ), suggesting that these types of AGN are missed in optical surveys. Using the [O iii] λ5007/Hβ and [N ii] λ6583/Hα emission-line diagnostic, about half of the sources are classified as Seyferts; ∼15% reside in dusty galaxies that lack an Hβ detection, but for which the upper limits on line emission imply either a Seyfert or LINER, are in galaxies with weak or no emission lines despite high-quality spectra, and a few percent each are LINERS, composite galaxies, H ii regions, or in known beamed AGNs.