Implications for unified schemes from submillimetre and far-infrared follow-up of radio-selected samples

We extend our previous analysis which used generalized luminosity functions (GLFs) to predict the number of quasars and galaxies in low-radio-frequency-selected samples as a function of redshift, radio luminosity, narrow-emission-line luminosity and type of unified scheme. Our extended analysis incorporates the observed submillimetre (850 micron) flux densities of radio sources, employs a new method which allows us to deal with non detections, and focuses on the high-luminosity population. First, we conclude that the submillimetre luminosity L_{850} of low-frequency-selected radio sources is correlated with the bolometric luminosity L_{Bol} of their quasar nuclei via an approximate scaling relation L_{850} \propto L_{Bol}^{0.7 \pm 0.2}. Second, we conclude that there is quantitative evidence for a receding-torus-like physical process for the high-luminosity population within a two-population unified scheme for radio sources; this evidence comes from the fact that radio quasars are brighter in both narrow emission lines and submillimetre luminosity than radio galaxies matched in radio luminosity and redshift. Third, we note that the combination of a receding-torus-like scheme and the assumption that the observed submillimetre emission is dominated by quasar-heated dust yields a scaling relation L_{850} \propto L_{Bol}^{0.5} which is within the errors of that determined here for radio-selected quasars, and consistent with that inferred for radio-quiet quasars by Willott, Rawlings & Grimes (2003).Comment: 13 pages (including an appendix), 5 figures, to appear in MNRA

The Connection between Ultraviolet and X-ray Outflows in AGN: the case of PDS 456

High-velocity outflows from AGN are a well-known phenomena in terms of the Broad Absorption Lines seen in the UV/optical. More recently, similar, possibly related, outflows have been reported in the X-ray. The most extreme example is seen in the nearby, luminous QSO PDS 456, which displays a massive, high velocity (50000 km s-1), high-ionization X-ray outflow of 10 solar masses yr-1. Here we present the UV spectrum of PDS 456 as observed by the Hubble Space Telescope. We find the UV spectrum is also extreme, displaying very broad emission-lines, with CIV 1549 blueshifted by 5000 km s-1 and a broad Ly-alpha absorption trough blueshifted by 14000-24000 km s-1. No strong, broad high-ionization absorption features are seen. We interpret the combined UV and X-ray spectrum of PDS 456 as the signature of a decelerating, cooling outflow, which may be driven by radiation and/or magnetic field. This outflow may be the source of some of the broad emission and absorption-line gas.Comment: Accepted for publication in MNRAS. 6 pages. 6 figure

Space Warps: I. Crowd-sourcing the Discovery of Gravitational Lenses

We describe Space Warps, a novel gravitational lens discovery service that yields samples of high purity and completeness through crowd-sourced visual inspection. Carefully produced colour composite images are displayed to volunteers via a web- based classification interface, which records their estimates of the positions of candidate lensed features. Images of simulated lenses, as well as real images which lack lenses, are inserted into the image stream at random intervals; this training set is used to give the volunteers instantaneous feedback on their performance, as well as to calibrate a model of the system that provides dynamical updates to the probability that a classified image contains a lens. Low probability systems are retired from the site periodically, concentrating the sample towards a set of lens candidates. Having divided 160 square degrees of Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) imaging into some 430,000 overlapping 82 by 82 arcsecond tiles and displaying them on the site, we were joined by around 37,000 volunteers who contributed 11 million image classifications over the course of 8 months. This Stage 1 search reduced the sample to 3381 images containing candidates; these were then refined in Stage 2 to yield a sample that we expect to be over 90% complete and 30% pure, based on our analysis of the volunteers performance on training images. We comment on the scalability of the SpaceWarps system to the wide field survey era, based on our projection that searches of 10$^5$ images could be performed by a crowd of 10$^5$ volunteers in 6 days.Comment: 21 pages, 13 figures, MNRAS accepted, minor to moderate changes in this versio

Molecular Hydrogen and Paschen-alpha Emission in Cooling Flow Galaxies

We present near-infrared spectra obtained to search for Pa-alpha and molecular hydrogen lines in edge-darkened (FR I-type) radio galaxies with bright Halpha emission in the redshift range 0.0535<z<0.15. We find that all three galaxies in our sample (PKS 0745-191, PKS 1346+26, & PKS2322-12) which are associated with strong cooling flows also have strong Pa-alpha and H_2 (1-0) S(1) through S(5) emission, while other radio galaxies do not. Together with earlier observations this confirms claims that cooling flow galaxies are copious emitters of molecular hydrogen with large H_2 (1-0) S(3)/Pa-alpha ratios in the range 0.5 to 2. The emission is centrally concentrated within the inner few kiloparsec and could come from warm (T ~ 1000-1500 K) molecular material which is being deposited by the cooling flow. We speculate that the H_2 emission could be related to the interaction between the jets and this molecular gas.Comment: ApJ Letters, in press, AAS LaTex, preprint also available at http://www.astro.umd.edu/~hfalcke/publications.html#nirga

Unproceedings of the Fourth .Astronomy Conference (.Astronomy 4), Heidelberg, Germany, July 9-11 2012

The goal of the .Astronomy conference series is to bring together astronomers, educators, developers and others interested in using the Internet as a medium for astronomy. Attendance at the event is limited to approximately 50 participants, and days are split into mornings of scheduled talks, followed by 'unconference' afternoons, where sessions are defined by participants during the course of the event. Participants in unconference sessions are discouraged from formal presentations, with discussion, workshop-style formats or informal practical tutorials encouraged. The conference also designates one day as a 'hack day', in which attendees collaborate in groups on day-long projects for presentation the following morning. These hacks are often a way of concentrating effort, learning new skills, and exploring ideas in a practical fashion. The emphasis on informal, focused interaction makes recording proceedings more difficult than for a normal meeting. While the first .Astronomy conference is preserved formally in a book, more recent iterations are not documented. We therefore, in the spirit of .Astronomy, report 'unproceedings' from .Astronomy 4, which was held in Heidelberg in July 2012.Comment: 11 pages, 1 figure, .Astronomy 4, #dotastr