Search Publications
The INTEGRAL/IBIS AGN catalogue - I. X-ray absorption properties versus optical classification
Masetti, N.; Bird, A. J.; Ubertini, P. +5 more
In this work we present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which we have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100 keV fluxes plus column density. Here we mainly use this sample to study the …
Coplanar circumbinary debris discs
Wyatt, M. C.; Matthews, B. C.; Kennedy, G. M. +3 more
We present resolved Herschel images of circumbinary debris discs in the α CrB (HD 139006) and β Tri (HD13161) systems. By modelling their structure, we find that both discs are consistent with being aligned with the binary orbital planes. Though secular perturbations from the binary can bring the disc into alignment, in both cases the alignment ti…
SX Phoenicis period-luminosity relations and the blue straggler connection
Cohen, Roger E.; Sarajedini, Ata
This study is aimed at investigating the period-luminosity relation of SX Phoenicis (SX Phe) pulsators in Galactic globular clusters (GGCs) and Local Group dwarf galaxies. We verify isochrone-fitting distances of 46 GGCs by fitting their main sequences to a carefully chosen set of nearby, unevolved subdwarfs. We find that the difference between cl…
Approximate Bayesian Computation for astronomical model analysis: a case study in galaxy demographics and morphological transformation at high redshift
Cameron, E.; Pettitt, A. N.
'Approximate Bayesian Computation' (ABC) represents a powerful methodology for the analysis of complex stochastic systems for which the likelihood of the observed data under an arbitrary set of input parameters may be entirely intractable - the latter condition rendering useless the standard machinery of tractable likelihood-based, Bayesian statis…
Testing the universality of star formation - I. Multiplicity in nearby star-forming regions
Patience, Jenny; Parker, Richard J.; King, Robert R. +1 more
We have collated multiplicity data for five clusters (Taurus, Chamaeleon I, Ophiuchus, IC 348 and the Orion Nebula Cluster). We have applied the same mass ratio (flux ratios of ΔK≤ 2.5) and primary mass cuts (∼0.1-3.0 M⊙) to each cluster and therefore have directly comparable binary statistics for all five clusters in the separation ran…
The MeV spectral tail in Cyg X-1 and optically thin emission of jets
Zdziarski, Andrzej A.; Sikora, Marek; Lubiński, Piotr
We study the average X-ray and soft γ-ray spectrum of Cyg X-1 in the hard spectral state, using data from INTEGRAL. We compare these results with those from CGRO, and find a good agreement. Confirming previous studies, we find the presence of a high-energy MeV tail beyond a thermal-Comptonization spectrum; however, the tail is much softer and weak…
Substructure in the lens HE 0435-1223
Keeton, Charles R.; Fadely, Ross
We investigate the properties of dark matter substructure in the gravitational lens HE 0435-1223 (zl=0.455) via its effects on the positions and flux ratios of the quadruply imaged background quasar (zs= 1.689). We start with a smooth mass model, add individual, truncated isothermal clumps near the lensed images and use the B…
Observing simulated galaxy clusters with PHOX: a novel X-ray photon simulator
Böhringer, H.; Dolag, K.; Lemson, G. +1 more
We present a novel, virtual X-ray observatory designed to obtain synthetic observations from hydro-numerical simulations, named PHOX. In particular, we provide a description of the code constituting the photon simulator and of the new approach implemented. We apply PHOX to simulated galaxy clusters in order to demonstrate its capabilities. In fact…
Signatures of minor mergers in Milky Way like disc kinematics: ringing revisited
Gómez, Facundo A.; Minchev, Ivan; O'Shea, Brian W. +2 more
By means of N-body simulations, we study the response of a galactic disc to a minor merger event. We find that non-self-gravitating, spiral-like features are induced in the thick disc. As we have shown in a previous work, this 'ringing' also leaves an imprint in velocity space (the u-v plane) in small spatial regions, such as the solar neighbourho…
The dust energy balance in the edge-on spiral galaxy NGC 4565
Gordon, Karl D.; De Looze, Ilse; Baes, Maarten +20 more
We combine new dust continuum observations of the edge-on spiral galaxy NGC 4565 in all Herschel/Spectral and Photometric Imaging Receiver (250, 350 and 500 µm) wavebands, obtained as part of the Herschel Reference Survey, and a large set of ancillary data (Spitzer, Sloan Digital Sky Survey, Galaxy Evolution Explorer) to analyse its dust ene…