We have applied ClassX, an oblique decision tree classifier optimized for astronomical analysis, to the homogeneous multicolor imaging data base of the Sloan Digital Sky Survey (SDSS), training the software on subsets of SDSS objects whose nature is precisely known via spectroscopy. We find that the software, using photometric data only, correctly classifies a very large fraction of the objects...

We present the results of a Spitzer search for obscured AGN in the Chandra Deep Field-North, using both radio-excess and mid-infrared power-law selection. AGN selected via the former technique tend to lie at z ∼ 1, have SEDs dominated by the 1.6 μm stellar bump, and have Seyfert-like X-ray luminosities (when detected in the X-ray). In contrast, the IRAC (3.6-8.0 μm) power-law selected AGN lie a...

We estimate the abundance of Compton-thick (CT) active galactic nuclei (AGN) based on our joint model of X-ray and infrared backgrounds. At Lrest2−10keV > 10 42 erg/s, the CT AGN density predicted by our model is a few ×10 Mpc from z=0 up to z=3. CT AGN with higher luminosity cuts (> 10, 10 & 10 erg/s) peak at higher z and show a rapid increase in the number density from z=0 to z∼2-3. The CT to...

We have reported that a 10-herbal traditional formula containing Korean Angelica gigas Nakai (AGN) exerts potent anti-cancer efficacy and identified decursin and decursinol angelate (DA) from AGN as novel anti-androgens. Here, we determined whether AGN would exert in vivo anti-cancer activity and whether decursin or DA could account for its efficacy. The AGN ethanol extract was tested against t...

Active galactic nuclei (AGN) are prominent astrophysical objects that can be observed throughout the whole Universe. To understand the underlying physical processes and the different appearance of AGN types, extensive samples are needed. Nowadays, various AGN catalogs are available at different wavebands. However, at the highest redshifts data are still relatively sparse. These data are require...

We discuss the relationship between rest-frame color and optical luminosity for X-ray sources in the range 0.6 < z < 1.4 selected from the Chandra survey of the Extended Groth Strip (EGS). These objects are almost exclusively active galactic nuclei (AGN). While there are a few luminous QSOs, most are relatively weak or obscured AGN whose optical colors should be dominated by host galaxy light. ...

Our analysis on the two magnitude-limited samples of LINERs suggests a correlation between LFIR/LB or f(25μm)/f(60μm), and Hubble-type index at >99.99% significance level. As LFIR/LB and f(25μm)/f(60μm) are considered as the indicators of star-formation activity and AGN activity, respectively, our result suggests that LINERs with higher AGN activity may have a lower star-formation contribution....

We have determined the cosmological evolution of the density of active galactic nuclei (AGN) and of their NH distribution as a function of the un–absorbed 2–10 keV luminosity up to redshift 4. We used the HELLAS2XMM sample combined with other published catalogs, yielding a total of 508 AGN. Our best fit is obtained with a luminosity-dependent density evolution (LDDE) model where low luminosity ...

We have analyzed new, archival and published high resolution radio and X-ray observations of a sample of composite LINER/H ii galaxies known to exhibit AGN-like properties. Five of the 16 AGN candidates have milliarcsecond-scale detections and are found to display a compact, flat spectrum, high brightness temperature radio core, four of which also exhibit extended radio emission. Five of the ei...

We apply a simple model, tested on local ULIRGs, to disentangle the active galactic nucleus (AGN) and starburst contributions in submillimiter and 24 μm-selected ULIRGs observed with the Spitzer-IRS spectrometer. We quantitatively estimate the average AGN contribution to the stacked 6−8 μm rest-frame spectra of these sources in different luminosity and redshift ranges, and, under the assumption...