Quasar Selection

Quasars were selected in the SN fields imaged as part of DES-SV using the following criteria:
  • Choose point sources using des_spreadmodel_r < 0.005
  • Target only rAB < 22.5 sources to get reasonable S/N in ~1hr integration on AAT
  • DES+VISTA colour cuts: (u-g)>0.4 & (g-i)<=1.5 & (g-i) < 1.15291*(i-K)-1.40117 (empirically derived relation using SDSS data)
  • WISE colour cut: (3.4um - 4.6um) > 0.7
Summary of AAT Observations so far:
  • Spectra taken for ~60 quasars + an additional few photo-z targets which turn out to be quasars
  • AAT Pipeline assigns secure redshifts to ~40 of these
  • Eyeballing spectra - some contamination from low redshift ellipticals but ~25 have clear broad lines visible in the spectra
  • Mean redshift = 1.8, Max redshift = 3.2
  • Three show prominent BAL features