This is the astro-ph blog of the Theoretical Modelling of Cosmic Structures group (TMoX) at the Max-Planck-Institute for Extraterrestrial Physics. We are an independent Max-Planck Research Group focusing on the various aspects in the formation and evolution of galaxies. Part of our focus is on the formation and evolution of early-type galaxies, super-massive black holes, the formation of the first structures in the universe and the enrichment history of the Universe. We are theoreticians using analytic modelling as well as numerical simulations in our work.

The CosmologyCake blog is dedicated to the discussion of research papers and current developments. We will regularly post interesting papers and comment on them. Feel free to leave your comments as well. We encourage authors of discussed papers to post replies if they wish to. Our aim is to provide a platform to discuss recent astro-ph papers within a wider audience. Please feel free to send papers you would like to be discussed to us at

11 May 2012

The radius of baryonic collapse in disc galaxy formation

Authors: Kassin et al.
Link: here.

The authors propose a simple solution for the angular momentum catastrophe: measure the DM specific angular momentum (j) at the radius of baryonic collapse, defined as R_BC in their work, which is smaller than the R_vir and hence has a higher concentration of DM encompassed in it. Assuming the standard picture of galaxy formation where the baryons collapse from inside to outside in a DM halo, they are able to make a reasonable case for their R_BC parameter. The measurement of j at an inner radius leads to an agreement in the baryonic and DM j which they are able to constrain from observational data. Although they only run a DM-only simulation, certain assumptions about the j of the observed spiral galaxies (relating their circular velocity to the angular momentum) allow them to relate their simulated DM haloes and observed galaxies.

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