X-ray observations of the Ultraluminous infrared galaxy IRAS19254-7245 (The Superantennae)

We present ROSAT HRI and ASCA observations of the well known ULIRG IRAS19254-7245 (the Superantennae). The object is not detected by ROSAT yielding a 3\sigma upper limit of L_x ~8x10^{41} erg/s in the 0.1-2 keV band. However, we obtain a clear detection by ASCA yielding a luminosity in the 2-10 keV band of 2 \times 10^{42}erg/s. Its X-ray spectrum is very hard, equivalent to a photon index of Gamma=1.0+-0.35. We therefore, attempt to model the X-ray data with a "scatterer" model in which the intrinsic X-ray emission along our line of sight is obscured by an absorbing screen while some fraction, f, is scattered into our line of sight by an ionized medium; this is the standard model for the X-ray emission in obscured (but non Compton-thick) Seyfert galaxies. We obtain an absorbing column of 2x10^{23}cm^{-2} for a power-law photon index of Gamma=1.9, an order of magnitude above the column estimated on the basis of optical observations; the percentage of the scattered emission is high (~20%). Alternatively, a model where most of the X-ray emission comes from reflection on a Compton thick torus (N_H>10^{24} cm^{-2}) cannot be ruled out. We do not detect an Fe line at 6.4 keV; however, the upper limit (90%) to the equivalent width of the 6.4 keV line is high (~3 keV). All the above suggest that most of the X-ray emission originates in an highly obscured Seyfert-2 nucleus.Comment: 5 pages, 1 figure, 1 table, To appear in MNRA

ROSAT observations of two 'cooling flow' EMSS Galaxies

We present ROSAT observations of two luminous L~10^44 erg/s EMSS galaxies, MS1019+5139 and MS1209+3917, previously classified as 'cooling flow' galaxies. MS1019+5139 does not appear to be spatially extended (<13 kpc) while its spectrum is well fit by a power law with Gamma = 1.73 +0.19-0.18; X-ray variability on a timescale of ~ years is also clearly detected. MS1209+3917 shows no evidence of spatial extension (<50 kpc) but it shows variability, while its spectrum can be fit with thermal bremsstrahlung emission (kT=1.8 +0.9-0.4 keV) or a power law model (Gamma = 2.50 +0.44-0.42, but with excess photoelectric absorption above the Galactic value). All the above argue against thermal emission from a group of galaxies or a galaxy but in favour of an AGN (possibly BL Lac) interpretation. We conclude that no 'normal' galaxies with high X-ray luminosities have yet been detected in the EMSS survey that could be significant contributors to the X-ray background.Comment: 6 pages, LaTeX, 6 postscript figures included, to appear in MNRA

Automatic holographic droplet analysis for liquid fuel sprays

The basic scheme for automated holographic analysis involves an optical system for reconstruction of the three dimensional real image of the droplet field, a spatial scanning system to transport a digitizing X-y image sensor through the real image, and processing algorithms for droplet recognition which establish the droplet sizes and positions. The hardware for system demonstrated includes the expanded and collimated beam from a 5 mW helium-neon laser for hologram reconstruction, an imaging lens for magnification of the real image field, and a video camera and digitizer providing 512-by-512 pixel resolution with 8-bit digitization. A mechanical stage is used to scan the hologram in three dimensional space, maintaining constant image magnification. A test droplet hologram is used for development and testing of the image processing algorithms

On the arcmin structure of the X-ray Universe

We present the angular correlation function of the X-ray population of 1063 XMM-Newton observations at high Galactic latitudes, comprising up to ~30000 sources over a sky area of ~125 sq. degrees in the energy bands: soft (0.5-2 keV) and hard (2-10 keV). This is the largest sample of serendipitous X-ray sources ever used for clustering analysis purposes to date and the results have been determined with unprecedented accuracy. We detect significant clustering signals in the soft and hard bands (~10 sigma and ~5 sigma, respectively). We deproject the angular correlation function via Limber's equation and calculate the typical spatial lengths. We infer that AGN at redshifts ~1 are embedded in dark matter halos with typical masses of log M ~ 12.6/h Msol and lifetimes in the range ~3-5 x 10^8 years, which indicates that AGN activity is a transient phase in the life of galaxies.Comment: 4 pages, 1 figure. Proc. of the conference "X-ray Astronomy 2009: Present status, multiwavelength approach and future perspectives", September 2009, Bologna. To appear in AIP Conf. Proc. (editors: A. Comastri, M. Cappi, L. Angelini)

The XMM-Newton spectral-fit database

The XMM-Newton spectral-fit database is an ongoing ESA funded project aimed to construct a catalogue of spectral-fitting results for all the sources within the XMM-Newton serendipitous source catalogue for which spectral data products have been pipeline-extracted (~ 120,000 X-ray source detections). The fundamental goal of this project is to provide the astronomical community with a tool to construct large and representative samples of X-ray sources by allowing source selection according to spectral properties.Comment: Conference proceedings of IAU Symposium 304: Multiwavelength AGN surveys and studie

Grid infrastructures for the electronics domain: requirements and early prototypes from an EPSRC pilot project

The fundamental challenges facing future electronics design is to address the decreasing – atomistic - scale of transistor devices and to understand and predict the impact and statistical variability these have on design of circuits and systems. The EPSRC pilot project “Meeting the Design Challenges of nanoCMOS Electronics” (nanoCMOS) which began in October 2006 has been funded to explore this space. This paper outlines the key requirements that need to be addressed for Grid technology to support the various research strands in this domain, and shows early prototypes demonstrating how these requirements are being addressed

Supporting security-oriented, collaborative nanoCMOS electronics research

Grid technologies support collaborative e-Research typified by multiple institutions and resources seamlessly shared to tackle common research problems. The rules for collaboration and resource sharing are commonly achieved through establishment and management of virtual organizations (VOs) where policies on access and usage of resources by collaborators are defined and enforced by sites involved in the collaboration. The expression and enforcement of these rules is made through access control systems where roles/privileges are defined and associated with individuals as digitally signed attribute certificates which collaborating sites then use to authorize access to resources. Key to this approach is that the roles are assigned to the right individuals in the VO; the attribute certificates are only presented to the appropriate resources in the VO; it is transparent to the end user researchers, and finally that it is manageable for resource providers and administrators in the collaboration. In this paper, we present a security model and implementation improving the overall usability and security of resources used in Grid-based e-Research collaborations through exploitation of the Internet2 Shibboleth technology. This is explored in the context of a major new security focused project at the National e-Science Centre (NeSC) at the University of Glasgow in the nanoCMOS electronics domain