Search Publications
The X-ray spectral evolution of the ultraluminous X-ray source Holmberg IX X-1
Done, Chris; Roberts, Timothy P.; Luangtip, Wasutep
We present a new analysis of X-ray spectra of the archetypal ultraluminous X-ray source (ULX) Holmberg IX X-1 obtained by the Swift, XMM-Newton and NuSTAR observatories. This ULX is a persistent source, with a typical luminosity of ∼1040 erg s-1, that varied by a factor of 4-5 over eight years. We find that its spectra tend t…
Statistical analysis of suprathermal electron drivers at 67P/Churyumov-Gerasimenko
Frahm, R. A.; Eriksson, A.; Henri, P. +16 more
We use observations from the Ion and Electron Sensor (IES) on board the Rosetta spacecraft to study the relationship between the cometary suprathermal electrons and the drivers that affect their density and temperature. We fit the IES electron observations with the summation of two kappa distributions, which we characterize as a dense and warm pop…
Testing deviations from ΛCDM with growth rate measurements from six large-scale structure surveys at z = 0.06-1
Ho, Shirley; Silvestri, Alessandra; Alam, Shadab
We use measurements from the Planck satellite mission and galaxy redshift surveys over the last decade to test three of the basic assumptions of the standard model of cosmology, ΛCDM (Λ cold dark matter): the spatial curvature of the universe, the nature of dark energy and the laws of gravity on large scales. We obtain improved constraints on seve…
Quantifying tensions between CMB and distance data sets in models with free curvature or lensing amplitude
Mohr, J. J.; Saro, A.; Dietrich, J. P. +2 more
Recent measurements of the cosmic microwave background (CMB) by the Planck Collaboration have produced arguably the most powerful observational evidence in support of the standard model of cosmology, I.e. the spatially flat ΛCDM paradigm. In this work, we perform model selection tests to examine whether the base CMB temperature and large scale pol…
Relativistic X-ray reverberation modelling of the combined time-averaged and lag-energy spectra in AGN
Chainakun, P.; Young, A. J.; Kara, E.
General relativistic ray tracing simulations of the time-averaged spectrum and energy-dependent time delays in active galactic nuclei (AGN) are presented. We model the lamp-post geometry in which the accreting gas is illuminated by an X-ray source located on the rotation axis of the black hole. The spectroscopic features imprinted in the reflectio…
Subaru Telescope adaptive optics observations of gravitationally lensed quasars in the Sloan Digital Sky Survey
Terada, Hiroshi; Pyo, Tae-Soo; Oguri, Masamune +12 more
We present the results of an imaging observation campaign conducted with the Subaru Telescope adaptive optics system (IRCS+AO188) on 28 gravitationally lensed quasars and candidates (23 doubles, 1 quad, 1 possible triple, and 3 candidates) from the SDSS Quasar Lens Search. We develop a novel modelling technique that fits analytical and hybrid poin…
Discrepancies between CFHTLenS cosmic shear and Planck: new physics or systematic effects?
Verde, Licia; Jimenez, Raul; Kitching, Thomas D. +1 more
There is currently a discrepancy in the measured value of the amplitude of matter clustering, parametrized using σ8, inferred from galaxy weak lensing, and cosmic microwave background (CMB) data, which could be an indication of new physics, such as massive neutrinos or a modification to the gravity law, or baryon feedback. In this paper…
The temporal evolution of exposed water ice-rich areas on the surface of 67P/Churyumov-Gerasimenko: spectral analysis
Mottola, S.; Barucci, M. A.; Kappel, D. +16 more
Water ice-rich patches have been detected on the surface of comet 67P/Churyumov-Gerasimenko by the VIRTIS (Visible InfraRed and Thermal Imaging Spectrometer) hyperspectral imager on board the Rosetta spacecraft, since the orbital insertion in late 2014 August. Among these, three icy patches have been selected, and VIRTIS data are used to analyse t…
67P/C-G inner coma dust properties from 2.2 au inbound to 2.0 au outbound to the Sun
Lamy, P. L.; Fulle, M.; Rodrigo, R. +36 more
GIADA (Grain Impact Analyzer and Dust Accumulator) on-board the Rosetta space probe is designed to measure the momentum, mass and speed of individual dust particles escaping the nucleus of comet 67P/Churyumov-Gerasimenko (hereafter 67P). From 2014 August to 2016 June, Rosetta escorted comet 67P during its journey around the Sun. Here, we focus on …
The Carina Nebula and Gum 31 molecular complex - I. Molecular gas distribution, column densities, and dust temperatures
Elia, Davide; Molinari, Sergio; Burton, Michael +6 more
We report high-resolution observations of the 12CO(1-0) and 13CO(1-0) molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of The Mopra Southern Galactic Plane CO Survey. We cover 8 deg2 from l = 285° to 290°, and from b = -1.5° to +0.5°. The molecular gas column…