Chasing passive galaxies in the early Universe: a critical analysis in CANDELS GOODS-South

Understand

We search for passive galaxies at $z>3$ in the GOODS-South field, using different techniques based on photometric data, and paying attention to develop methods that are sensitive to objects that have become passive shortly before the epoch of observation.

• We use CANDELS HST catalogues, ultra-deep $Ks$ data and new IRAC photometry, performing spectral energy distribution fitting using models with abruptly quenched star formation histories.
• We then single out galaxies which are best fitted by a passively evolving model, and having only low probability $( < 5 \%)$ star-forming solutions.
• We verify the effects of including nebular lines emission, and we consider possible solutions at different redshifts.