Astronomers derive MOdified Newtonian Dynamics (MOND) rotation curves using the simple algebraic rule of calculating the acceleration as equal to the Newtonian acceleration (a) divided by some factor μ(a). However, there are velocity differences between this simple rule and the calculation derived from more sophisticated MOND versions such as AQUAL

The analysis of weak gravitational lensing in wide-field imaging surveys is considered to be a major cosmological probe of dark energy. Our capacity to constrain the dark energy equation of state relies on an accurate knowledge of the galaxy mean redshift ⟨z⟩. We investigate the possibility of measuring ⟨z⟩ with an accuracy better than 0.002 (1 + z

Galaxy clusters are the most massive gravitationally bound structures in the Universe and they play a key role in our understanding of structure formation and galaxy evolution. The particular conditions of these high density environments can have a significant effect on the evolution of galaxies. Previous studies have reported systematic

The Fermi Large Area Telescope gamma-ray source 3FGL J2039.6-5618 contains a periodic optical and X-ray source that was predicted to be a 'redback' millisecond pulsar (MSP) binary system. However, the conclusive identification required the detection of pulsations from the putative MSP. To better constrain the orbital parameters for a directed

We present modelling of the long-term optical light and radial velocity curves of the binary stellar system CXOGBS J175553.2-281633, first detected in X-rays in the Chandra Galactic Bulge Survey. We analysed 7 yr of optical I-band photometry from Optical Gravitational Lensing Experiment and found long-term variations from year to year. These long