http://arxiv.org/abs/1708.02950
Semi-analytical galaxy formation models are widely used to gain insight into the astrophysics of galaxy formation and in model testing, parameter space searching and mock catalogue building. They are very complementary to hydrodynamical simulations, which are more physically detailed but also much more computationally expensive. It is important to make semi-analytical models as physically consistent and well motivated as possible for the robustness of their applications. In this work we present a new, improved model for gas cooling in halos in semi-analytical models. Compared to previous cooling models, our new treatment incorporates a more consistent calculation of the hot gas cooling history, a more detailed modeling of the contraction of the hot gas halo induced by cooling, and a more detailed calculation of the angular momentum of cooled down gas. This model predicts higher cooled down masses than the cooling models previously used in GALFORM, closer to the predictions of cooling models in L-GALAXIES and MORGANA, even though those models are formulated differently. It also predicts cooled down angular momenta higher than in previous GALFORM cooling models, but generally lower than the predictions of L-GALAXIES and MORGANA. When used in the full galaxy formation model, this cooling model improves the predictions for early-type galaxy sizes in GALFORM.
J. Hou, C. Lacey and C. Frenk
Fri, 11 Aug 17
26/45
Comments: 29 pages, 9 figures, submitted to MNRAS