UV bright red-sequence galaxies: how do UV upturn systems evolve in
  redshift and stellar mass?
  The so-called ultraviolet (UV) upturn of elliptical galaxies is a phenomenon
characterised by the up-rise of their fluxes in bluer wavelengths, typically in
the 1,200-2,500A range. This work aims at estimating the rate of occurrence of
the UV upturn over the entire red-sequence population of galaxies that show
significant UV emission. This assessment is made considering it as function of
three parameters: redshift, stellar mass, and -- what may seem
counter-intuitive at first -- emission-line classification. We built a
multiwavelength spectro-photometric catalogue from the Galaxy Mass Assembly
survey, together with aperture-matched data from Galaxy Evolution Explorer
Medium-Depth Imaging Survey (MIS) and Sloan Digital Sky Survey, covering the
redshift range between 0.06 and 0.40. From this sample, we analyse the UV
emission among UV bright galaxies, by selecting those that occupy the
red-sequence locus in the (NUV-r) x (FUV-NUV) chart; then, we stratify the
sample by their emission-line classes. To that end, we make use of
emission-line diagnostic diagrams, focusing the analysis in retired/passive
lineless galaxies. Then, a Bayesian logistic model was built to simultaneously
deal with the effects of all galaxy properties (including emission-line
classification or lack thereof). The main results show that retired/passive
systems host an up-rise in the fraction of UV upturn or redshifts between 0.06
and 0.25, followed by an in-fall up to 0.35. Additionally, we show that the
fraction of UV upturn hosts rises with increasing stellar mass.
