Lecturer: Prof. Yehuda Hoffman Affiliation: Racah Institute of Physics, The Hebrew University of Jerusalem Abstract: The association of ‘Near Field’ and ‘Cosmology’ rests on the implicit Copernican assumption that the near field constitutes a typical patch of the universe. A key question that needs to be addressed is how typical the near field is, and thereby how relevant it is to cosmology at large. Constrained simulations embody Near Field Cosmology in the realm of cosmological simulations and are used here to shed light on the problem. Recent advances in the setting of constrained initial conditions and the availability of the Cosmicflows-2 database of galaxy velocities have paved the way to the mass production of constrained simulations of the local universe. Of particular interest is the ability to produce in abundance Local Group (LG) like objects by our Local Group Factory. This opens a new era in which the Copernican nature of the LG and the near field can be studied statistically. We present a Bayesian framework for assessing the question of how typical is the LG. The problem of the mass of the LG is considered here as an example. This needs to be addressed within a context - a prior knowledge of the standard cosmological model (ΛCDM) and a LG model that defines what a LG is. The Cosmicflows-2 data adds new information on the local universe and it should be used to update our knowledge of the LG. Constrained simulations are the optimal mean for sampling the posterior probability of the mass of the LG and its environment. Additional details of the upcoming Astrophysics' seminars can be found on the following link. ‏האירוע הזה כולל שיחת וידאו ב-Google Hangouts. הצטרף: https://plus.google.com/hangouts/_/mail.huji.ac.il/astrophysics?hceid=bWFpbC5odWppLmFjLmlsX2c0czhydDlpcmhwZzRvdGNybWIzZGFqcjdvQGdyb3VwLmNhbGVuZGFyLmdvb2dsZS5jb20.rqc4srgice9fbfs0mbc08tsl0k&hs=121