Context. An electron-positron beam escaping from the magnetospheric vacuum gap of an accreting black hole interacts with recombination-line photons from surrounding gas clouds. Inverse-Compton scattering and subsequent pair production initiate unsaturated electromagnetic cascades exhibiting a characteristic spectral energy distribution. Aims: By

We use semi-analytical methods to obtain detailed chemical evolution models (CEMs) for the dwarf spheroidal (dSph) galaxy Tucana. Published star formation rates and the age-metallicity relationship are used to constrain the observables. The results show that Tucana: (i) behaved like a closed box for 75 per cent of its life, (ii) had either a

MAXI J1659-152 is a 2.4 h orbital period X-ray dipping transient black hole candidate. We present spectroscopy of its I ≍ 23 quiescent counterpart, where we detect Hα emission with full width half maximum (FWHM) of 3200 ± 300 km s -1. Applying the correlation between the Hα FWHM and radial velocity semi-amplitude of the donor star for quiescent X

We introduce a new software package for modelling the point spread function (PSF) of astronomical images, called PIFF (PSFs In the Full FOV), which we apply to the first three years (known as Y3) of the Dark Energy Survey (DES) data. We describe the relevant details about the algorithms used by PIFF to model the PSF, including how the PSF model