Search Publications
Search for X-ray occultations in active galactic nuclei
Salvati, M.; Risaliti, G.; Pietrini, P. +1 more
Recent time-resolved spectral studies of a few active galactic nuclei (AGNs) in hard X-rays revealed occultations of the X-ray primary source probably by broad-line region (BLR) clouds. An important open question on the structure of the circumnuclear medium of AGN is whether this phenomenon is common, i.e. whether a significant fraction of the X-r…
First detection and characterization of symbiotic stars in M31
Caldwell, Nelson; Mikołajewska, Joanna; Shara, Michael M.
Symbiotic binaries are putative progenitors of Type Ia supernovae. The census of Galactic symbiotic binaries is so incomplete that we cannot reliably estimate the total population of these stars, and use it to check whether that number is consistent with the observed Type Ia supernova rate in spiral galaxies. We have thus begun a survey of the nea…
A comparative study of radio halo occurrence in SZ and X-ray selected galaxy cluster samples
Basu, Kaustuv; Sommer, Martin W.
We aim at an unbiased census of the radio halo population in galaxy clusters and test whether current low number counts of radio haloes have arisen from selection biases. We construct near-complete samples based on X-ray and Sunyaev-Zel'dovich (SZ) effect cluster catalogues and search for diffuse, extended (Mpc-scale) emission near the cluster cen…
A physical model for the X-ray time lags of narrow-line Seyfert type 1 active galactic nuclei
Done, Chris; Gardner, Emma
We study the origin of the soft X-ray excess seen in the `simple' narrow-line Seyfert 1 galaxy PG1244+026 using all available spectral-timing information. This object shows the now ubiquitous switch between soft leading the hard band on long time-scales, to the opposite behaviour on short time-scales. This is interpreted as a combination of intrin…
Dissecting the origin of the submillimetre emission in nearby galaxies with Herschel and LABOCA
Roussel, H.; Hunt, L. K.; Weiss, A. +17 more
We model the infrared to submillimetre spectral energy distribution of 11 nearby galaxies of the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel sample using Spitzer and Herschel data and compare model extrapolations at 870 µm (using different fitting techniques) with Large APEX BOlometer CAmera (LABOCA) 870 µm obs…
The dust masses of powerful radio galaxies: clues to the triggering of their activity.
Ysard, N.; Morganti, R.; Nesvadba, N. +4 more
We use deep Herschel Space Observatory observations of a 90 per cent complete sample of 32 intermediate-redshift 2Jy radio galaxies (0.05 < z < 0.7) with strong emission lines to estimate the dust masses of their host galaxies and thereby investigate the triggering mechanisms for their quasar-like AGN. The dust masses derived for the radio g…
Combined analysis of Hubble and VLT photometry of the intermediate mass black hole ESO 243-49 HLX-1
Maccarone, T. J.; Knigge, C.; Soria, R. +11 more
In this paper, we present a combined analysis of data obtained with the Hubble Space Telescope (HST), Very Large Telescope (VLT) and Swift X-ray telescope of the intermediate-mass black hole ESO 243-49 HLX-1 that were taken two months apart between 2010 September and November. Previous separate analyses of these data found that they were consisten…
New insights on accretion in supergiant fast X-ray transients from XMM-Newton and INTEGRAL observations of IGR J17544-2619
Hill, A. B.; Sidoli, L.; Bird, A. J. +4 more
XMM-Newton observations of the supergiant fast X-ray transient IGR J17544-2619 are reported and placed in the context of an analysis of archival INTEGRAL/IBIS data that provide a refined estimate of the orbital period at 4.9272 ± 0.0004 d. A complete outburst history across the INTEGRAL mission is reported. Although the new XMM-Newton observations…
A Chandra look at the X-ray faint millisecond pulsars in the globular cluster NGC 6752
Heinke, C. O.; Cohn, H. N.; Lugger, P. M. +5 more
We combine new and archival Chandra observations of the globular cluster NGC 6752 to create a deeper X-ray source list, and study the faint radio millisecond pulsars (MSPs) of this cluster. We detect four of the five MSPs in NGC 6752, and present evidence for emission from the fifth. The X-rays from these MSPs are consistent with thermal emission …
Principal component analysis of MCG-06-30-15 with XMM-Newton
Fabian, A. C.; Brenneman, L.; Matt, G. +4 more
We analyse the spectral variability of MCG-06-30-15 with 600 k s of XMM-Newton data, including 300 k s of new data from the joint XMM-Newton and NuSTAR 2013 observational campaign. We use principal component analysis to find high-resolution, model-independent spectra of the different variable components of the spectrum. We find that over 99 per ce…