Search Publications
X-ray selected starbursts in the Great Observatories Origins Deep Survey-North
Georgakakis, A.; Georgantopoulos, I.; Rowan-Robinson, M. +1 more
We investigate claims that recent ultra-deep X-ray surveys are detecting starbursts at cosmologically interesting redshifts (z = 0-1). We combine X-ray data from the 2Ms Chandra Deep Field-North and multiwavelength observations obtained as part of the Great Observatories Origins Deep Survey (GOODS)-North to build the Spectral Energy Distributions …
Two newly identified, relatively old star clusters in the Small Magellanic Cloud
Piatti, Andrés E.; Sarajedini, Ata; Geisler, Doug +2 more
We present the results on the age and metallicity estimates of the Small Magellanic Cloud (SMC) clusters L110, L112 and L113 obtained from CCD Washington CT1 photometry. We confirm L113 as a relatively old and metal-poor cluster, and report for the first time that L110 and 112 are also relatively old clusters (t~ 6.5 Gyr). Their derived…
Hard X-ray emission of the Earth's atmosphere: Monte Carlo simulations
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +1 more
We perform Monte Carlo simulations of cosmic ray-induced hard X-ray radiation from the Earth's atmosphere. We find that the shape of the spectrum emergent from the atmosphere in the energy range 25-300 keV is mainly determined by Compton scatterings and photoabsorption, and is almost insensitive to the incident cosmic ray spectrum. We provide a fi…
Now you see it, now you don't - the circumstellar disc in the GRO J1008-57 system
Hill, A. B.; Coe, M. J.; Bird, A. J. +7 more
Multiwavelength observations are reported here of the Be/X-ray binary pulsar system GRO J1008-57. Over ten years worth of data are gathered together to show that the periodic X-ray outbursts are dependant on both the binary motion and the size of the circumstellar disc. In the first instance an accurate orbital solution is determined from pulse pe…
Reconstructing the history of dark energy using maximum entropy
Trotta, Roberto; Zunckel, Caroline
We present a Bayesian technique based on a maximum-entropy method to reconstruct the dark energy equation of state (EOS) w(z) in a non-parametric way. This Maximum Entropy (MaxEnt) technique allows to incorporate relevant prior information while adjusting the degree of smoothing of the reconstruction in response to the structure present in the dat…
X-ray and optical variability of Seyfert 1 galaxies as observed with XMM-Newton
Smith, R.; Vaughan, S.
We have examined simultaneous X-ray and optical light curves of a sample of eight nearby Seyfert 1 galaxies observed using the European Photon Imaging Camera (EPIC) X-ray cameras and Optical Monitor onboard XMM-Newton. The observations span ~1 d and revealed optical variability in four of the eight objects studied. In all the cases, the X-ray vari…
Morphologies and stellar populations of galaxies in the core of Abell 2218
Covone, G.; Sánchez, S. F.; Cardiel, N. +2 more
We present a study of the stellar populations and morphologies of galaxies in the core of the galaxy cluster Abell 2218. Integral field spectroscopy (IFS) observations were performed using PMAS in the PPAK mode covering a field of view of ~74 × 64 arcsec2 centred on the core of the cluster, in order to obtain spectroscopy of an unbiased…
The ISO LWS high-resolution spectral survey towards Sagittarius B2
Cernicharo, José; Polehampton, Edward T.; Swinyard, Bruce M. +5 more
A full spectral survey was carried out towards the giant molecular cloud complex, Sagittarius B2 (SgrB2), using the Infrared Space Observatory (ISO) Long Wavelength Spectrometer (LWS) Fabry-Pérot mode. This provided complete wavelength coverage in the range 47-196µm (6.38-1.53THz) with a spectral resolution of 30-40kms-1. This is …
HESS J1616-508: likely to be powered by PSR J1617-5055
de Rosa, A.; Bird, A. J.; Ubertini, P. +3 more
HESS J1616-508 is one of the brightest emitters in the TeV sky. Recent observations with the IBIS/ISGRI telescope onboard the INTEGRAL spacecraft have revealed that a young, nearby and energetic pulsar, PSR J1617-5055, is a powerful emitter of soft γ-rays in the 20-100 keV domain. In this paper, we present an analysis of all available data from th…
An XMM-Newton view of the young open cluster NGC 6231 - III. Optically faint X-ray sources
Gosset, E.; Rauw, G.; Vreux, J. -M. +2 more
We discuss the properties of the X-ray sources with faint optical counterparts in the very young open cluster NGC 6231. From their positions in the Hertzsprung-Russell diagram, we find that the bulk of these objects probably consists of low-mass pre-main-sequence (PMS) stars with masses in the range 0.3-3.0 Msolar. The age distribution …