J-PLUS: Synthetic galaxy catalogues with emission lines for photometric surveys

摘要

We present a synthetic galaxy lightcone specially designed for narrow-band optical photometric surveys. To reduce time-discreteness effects, unlike previous works, we directly include the lightcone construction in the L-Galaxies semi-analytic model applied to the subhalo merger trees of the Millennium simulation. Additionally, we add a model for the nebular emission in star-forming regions, which is crucial for correctly predicting the narrow- and medium-band photometry of galaxies. Specifically, we consider, individually for each galaxy, the contribution of 9 different lines: Ly α (1216 ?), H β (4861 ?), H α (6563 ?), [O? II ] (3727 ?, 3729 ?), [O? III ] (4959 ?, 5007 ?), [Ne? III ] (3870 ?), [O? I ] (6300 ?), [N? II ] (6548 ?, 6583 ?), and [S? II ] (6717 ?, 6731 ?). We validate our lightcone by comparing galaxy number counts, angular clustering, and H α , H β , [O? II ], and [O? III ]_(5007)luminosity functions to a compilation of observations. As an application of our mock lightcones, we generated catalogues tailored for J-PLUS, a large optical galaxy survey featuring five broad-band and seven medium-band filters. We study the ability of the survey to correctly identify, with a simple three-filter method, a population of emission-line galaxies at various redshifts. We show that the 4000 ? break in the spectral energy distribution of galaxies can be misidentified as line emission. However, all significant excess (> 0.4 mag) can be correctly and unambiguously attributed to emission-line galaxies. Our catalogues are publicly released to facilitate their use in interpreting narrow-band surveys and in quantifying the impact of line emission in broad-band photometry.