2017/09/27 by Peter Mitchell, Peter D. Mitchell, C. G. Lacey +13 · 55 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Physics #Radio Astronomy Observations and Technology #Statistical physics #Theoretical physics #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stx2770
published in Monthly Notices of the Royal Astronomical Society 474(1), 492-521 (Oxford University Press) · some references corrected, 31 pages, 19 figures, submitted to MNRAS after responding to a first referee report
arxiv created 2017/09/27 · openalex created_date 2017/10/06 · openalex publication_date 2017/10/24 · arxiv updated 2017/12/20 · openalex updated_date 2026/08/05
Abstract It is now possible for hydrodynamical simulations to reproduce a representative galaxy population. Accordingly, it is timely to assess critically some of the assumptions of traditional semi-analytic galaxy formation models. We use the eagle simulations to assess assumptions built into the galform semi-analytic model, focusing on those relating to baryon cycling, angular momentum and feedback. We show that the assumption in galform that newly formed stars have the same specific angular momentum as the total disc leads to a significant overestimate of the total stellar specific angular momentum of disc galaxies. In eagle, stars form preferentially out of low-specific angular momentum gas in the interstellar medium due to the assumed gas density threshold for stars to form, leading to more realistic galaxy sizes. We find that stellar mass assembly is similar between galform and eagle but that the evolution of gas properties is different, with various indications that the rate of baryon cycling in eagle is slower than is assumed in galform. Finally, by matching individual galaxies between eagle and galform, we find that an artificial dependence of active galactic nucleus feedback and gas infall rates on halo mass-doubling events in galform drives most of the scatter in stellar mass between individual objects. Put together our results suggest that the galform semi-analytic model can be significantly improved in light of recent advances.