Toward a stellar population catalog in the Kilo Degree Survey: The impact of stellar recipes on stellar masses and star formation rates

The Kilo Degree Survey (KiDS) is currently the only sky survey providing optical (ugri) plus near-infrared (NIR, ZYHJK_S) seeing matched photometry over an area larger than 1000 deg². This is obtained by incorporating the NIR data from the VISTA Kilo Degree Infrared Galaxy (VIKING) survey, covering the same KiDS footprint. As such, the KiDS multi-wavelength photometry represents a unique dataset to test the ability of stellar population models to return robust photometric stellar mass (M_*) and star-formation rate (SFR) estimates. Here we use a spectroscopic sample of galaxies for which we possess ugriZY JHK_s "gaussianized" magnitudes from KiDS data release 4. We fit the spectral energy distribution from the 9-band photometry using: (1) three different popular libraries of stellar population templates, (2) single burst, simple and delayed exponential star-formation history models, and (3) a wide range of priors on age and metallicity. As template fitting codes we use two popular softwares: LePhare and CIGALE. We investigate the variance of the stellar masses and the star-formation rates from the different combinations of templates, star formation recipes and codes to assess the stability of these estimates and define some "robust" median quantities to be included in the upcoming KiDS data releases. As a science validation test, we derive the mass function, the star formation rate function, and the SFR-M_* relation for a low-redshift (z < 0.5) sample of galaxies, that result in excellent agreement with previous literature data. The final catalog, containing ∼ 290000 galaxies with redshift 0.01 < z < 0.9, is made publicly available.