Search Publications
Does the obscured AGN fraction really depend on luminosity?
Krivonos, R.; Sazonov, S.; Churazov, E.
We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstra…
The spatially-resolved star formation history of the M31 outer disc
Lewis, Geraint F.; McConnachie, Alan W.; Ibata, Rodrigo A. +4 more
We present deep Hubble Space Telescope Advanced Camera for Surveys observations of the stellar populations in two fields lying at 20 and 23 kpc from the centre of M31 along the south-west semimajor axis. These data enable the construction of colour-magnitude diagrams reaching the oldest main-sequence turn-offs (∼13 Gyr) which, when combined with a…
Constraints on neutrino mass from cosmic microwave background and large-scale structure
Knox, L.; Pan, Z.
Our tightest upper limit on the sum of neutrino mass eigenvalues Mν comes from cosmological observations that will improve substantially in the near future, enabling a detection. The combination of the baryon acoustic oscillation feature measured from the Dark Energy Spectroscopic Instrument and a Stage-IV Cosmic Microwave Background ex…
A magnetic reconnection model for explaining the multiwavelength emission of the microquasars Cyg X-1 and Cyg X-3
del Valle, M. V.; de Gouveia Dal Pino, E. M.; Khiali, B.
Recent studies have indicated that cosmic ray acceleration by a first-order Fermi process in magnetic reconnection current sheets can be efficient enough in the surrounds of compact sources. In this work, we discuss this acceleration mechanism operating in the core region of galactic black hole binaries (or microquasars) and show the conditions un…
Are the total mass density and the low-mass end slope of the IMF anticorrelated?
Koopmans, L. V. E.; Spiniello, C.; Trager, S. C. +1 more
We conduct a detailed lensing, dynamics and stellar population analysis of nine massive lens early-type galaxies (ETGs) from the X-Shooter Lens Survey (XLENS). Combining gravitational lensing constraints from HST imaging with spatially-resolved kinematics and line-indices constraints from Very Large Telescope (VLT) X-Shooter spectra, we infer the …
Chandra survey in the AKARI North Ecliptic Pole Deep Field - I. X-ray data, point-like source catalogue, sensitivity maps, and number counts
Malkan, M. A.; Pearson, C.; Takagi, T. +10 more
We present data products from the 300 ks Chandra survey in the AKARI North Ecliptic Pole Deep Field. This field has a unique set of nine-band infrared photometry covering 2-24 µm from the AKARI Infrared Camera, including mid-infrared (MIR) bands not covered by Spitzer. The survey is one of the deepest ever achieved at ∼15 µm, and is by…
Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by
Zheng, W.; Filippenko, A. V.; Foley, R. J. +6 more
The nearby Type Ia supernovae (SNe Ia) 2011fe and 2011by had nearly identical photospheric phase optical spectra, light-curve widths, and photometric colours, but at peak brightness SN 2011by reached a fainter absolute magnitude in all optical bands and exhibited lower flux in the near-ultraviolet (NUV). Based on those data, Foley & Kirshner a…
Biases in the determination of dynamical parameters of star clusters: today and in the Gaia era
Balbinot, E.; Hénault-Brunet, V.; Gieles, M. +4 more
The structural and dynamical properties of star clusters are generally derived by means of the comparison between steady-state analytic models and the available observables. With the aim of studying the biases of this approach, we fitted different analytic models to simulated observations obtained from a suite of direct N-body simulations of star …
Predicted properties of multiple images of the strongly lensed supernova SN Refsdal.
Oguri, M.
We construct a mass model of the cluster MACS J1149.6+2223 to study the expected properties of multiple images of SN Refsdal, the first example of a gravitationally lensed supernova with resolved multiple images recently reported by Kelly et al. We find that the best-fitting model predicts six supernova images in total, i.e. two extra images in ad…
Gaia's potential for the discovery of circumbinary planets
Sahlmann, J.; Martin, D. V.; Triaud, A. H. M. J.
The abundance and properties of planets orbiting binary stars - circumbinary planets - are largely unknown because they are difficult to detect with currently available techniques. Results from the Kepler satellite and other studies indicate a minimum occurrence rate of circumbinary giant planets of ∼10 per cent, yet only a handful are presently k…