We study the correlation between the [O III]λ5007 and X-ray luminosities of local active galactic nuclei (AGNs), using a complete, hard X-ray (>10 keV) selected sample in the Swift/BAT 9-month catalog. From our optical spectroscopic observations at the South African Astronomical Observatory and the literature, a catalog of ratios than the other absorbed AGNs, while those in edge-on host galaxies do not. These results suggest that a significant fraction of this population is buried in tori with small opening angles. By using these] versus L X correlations, the X-ray luminosity function (LF) of local AGNs (including Compton-thick AGNs) in a standard population synthesis model gives much better agreement with the [O III]λ5007 LF derived from the Sloan Digital Sky Survey than previously reported. This confirms that hard X-ray observations are a very powerful tool to find AGNs with high completeness.

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We have used narrow-band [OIII]λλ4959,5007 and Hα+ [NII]λλ6548, 84 Hubble Space Telescope (HST) images of 9 luminous (L[OIII]> 10 42 erg s −1 ) type 2 QSOs with redshifts 0.1 < z < 0.5 in order to constrain the geometry of their Extended Narrow-Line Regions (ENLR), as recent ground-based studies suggest these regions become more spherical at high luminosities due to destruction of the torus. We find instead elongated ENLRs reaching 4 to 19 kpc from the nucleus and bipolar ionization cones in [OIII]/(Hα+[NII]) excitation maps indicating that the torus survives these luminosities, allowing the escape of ≈ 10 times higher ionizing photon rates along the ionization axis than perpendicularly to it. The exceptional HST angular resolution was key to our success in arriving at these conclusions. Combining our measurements with previous ones based on similar HST data, we have revisited the relation between the ENLR radius R maj and L[OIII] over the range 39

Chemical forensics is a developing field that aims to attribute a chemical (or mixture) of interest to its source by the analysis of the chemical itself or associated material constituents. Herein, for the first time, trace impurities detected by gas chromatography/mass spectrometry and originating from a chemical precursor were used to match a synthesized nerve agent to its precursor source. Specifically, six batches of sarin (GB, isopropyl methylphosphonofluoridate) and its intermediate methylphosphonic difluoride (DF) were synthesized from two commercial stocks of 97% pure methylphosphonic dichloride (DC); the GB and DF were then matched by impurity profiling to their DC stocks from a collection of five possible stocks. Source matching was objectively demonstrated through the grouping by hierarchal cluster analysis of the GB and DF synthetic batches with their respective DC precursor stocks based solely upon the impurities previously detected in five DC stocks. This was possible because each tested DC stock had a unique impurity profile that had 57% to 88% of its impurities persisting through product synthesis, decontamination, and sample preparation. This work forms a basis for the use of impurity profiling to help find and prosecute perpetrators of chemical attacks.

Coronal-Line Forest Active Galactic Nuclei (CLiF AGN) are remarkable in the sense that they have a rich spectrum of dozens of coronal emission lines (e.g. [FeVII], [FeX] and [NeV]) in their spectra. Rose, Elvis & Tadhunter (2015) suggest that the inner obscuring torus wall is the most likely location of the coronal line region in CLiF AGN, and the unusual strength of the forbidden high ionization lines is due to a specific AGN-torus inclination angle. Here we test this suggestion using mid-IR colours