Universal Conditional Distribution Function of [O ii] Luminosity of Galaxies, and Prediction for the [O ii] Luminosity Function at Redshift z < 3

The star-forming emission line galaxies (ELGs) with a strong [O ii] doublet are one of the main spectroscopic targets for the ongoing and upcoming fourth-generation galaxy redshift surveys. In this work, we measure the [O ii] luminosity L _{[O II]} and the absolute magnitude in the near-ultraviolet (NUV) band M _NUV for a large sample of galaxies in the redshift range 0.6 ≤ z < 1.45 from the Public Data Release 2 (PDR-2) of the VIMOS Public Extragalactic Redshift Survey (VIPERS). We aim to construct the intrinsic relationship between L _{[O II]} and M _NUV through Bayesian analysis. In particular, we develop two different methods to properly correct for the incompleteness effect and observational errors in the [O ii] emission line measurement. Our results indicate that the conditional distribution of L _{[O II]} at a given M _NUV can be well described by a universal probability distribution function (PDF), which is independent of M _NUV and redshift. Convolving the L _{[O II]} conditional PDF with the NUV luminosity function (LF) available in the literature, we make a prediction for [O ii] LFs at z < 3. The predicted [O ii] LFs are in good agreement with the observational results from the literature. Finally, we utilize the predicted [O ii] LFs to estimate the number counts of [O ii] emitters for the Subaru Prime Focus Spectrograph survey. This universal conditional PDF of L _{[O II]} provides a novel way to optimize the source targeting strategy for [O ii] emitters in future galaxy redshift surveys, and to model [O ii] emitters in theories of galaxy formation.