Luminous star-forming galaxies in the SDSS-GALEX database

We use the combined photometric GALEX + SDSS database to look for populations of luminous blue star-forming galaxies. These were initially identified from such a sample at redshifts near 0.4, using SDSS spectra. We make use of the NUV, g, and i colour index previously defined in our previous paper, to separate stars and QSOs, to locate more of these unusual galaxies, to fainter limits. They are found in significant numbers in two different regions of the related colour-magnitude plot. Within these regions, we use the ensemble 7-colour photometry (FUV, NUV, u, g, r, i, z) to postulate the populations of blue star-forming galaxies at redshifts near 0.4 and 1.0, from a full photometric sample of over half a million.