Speaker:	Isabel Santos and Willem Elbers (Durham University)
Title:	The true radial distribution of satellite galaxies around MW-mass halos in LCDM / Coupling cosmology and baryonic feedback with FLAMINGO
Date (JST):	Tue, Nov 07, 2023, 11:00 - 13:00
Place:	Seminar Room A
Abstract:	Author: Dr Isabel Santos-Santos The true radial distribution of satellite galaxies around MW-mass halos in LCDM The MW galaxy presents a larger number of satellites within 20 kpc than predicted by cosmological simulations of MW halos. If we believe simulation results, one implication is that halos as small as Vpeak~7 km/s should harbour galaxies, which is in contrast to the expectations of most galaxy formation models. On the other hand, idealized simulations predict that the cuspy NFW density profile of cold dark matter halos always survives tidal stripping, leaving a compact remnant. This framework has highlighted that cosmological N-body simulations suffer from artificial disruption of subhalos near the centers of MW-mass halos after tidal stripping. This is a numerical limitation due to the finite mass resolution currently achievable in these simulations. In this work we use the Aquarius simulations of MW-mass halos, combined with the Galform semi-analytical galaxy formation model, to account for these sub-resolution subhalos (commonly known as “type-2s/orphans”) and estimate the true radial distribution of subhalos predicted by LCDM. We carry out a convergence study of the number of type-2s versus surviving satellites by comparing 5 different resolution levels and characterizing the population of type-2s. Our results show that the observed population of nearby ultrafaint MW satellites can be readily accommodated within LCDM and models where galaxy formation occurs in halos with masses above the Hydrogen-cooling limit. Author: Dr Willem Elbers Coupling cosmology and baryonic feedback with FLAMINGO To constrain our cosmological model and to measure key physical parameters, like the sum of neutrino masses, with galaxy surveys like DESI, Euclid, and LSST, precise theoretical modelling of the large-scale structure is indispensable. One of the main uncertainties limiting the accuracy of our predictions on non-linear scales relates to the impact of baryonic feedback processes. FLAMINGO is a new suite of cosmological hydrodynamical simulations aimed at quantifying baryonic uncertainties and producing mock observations of large-scale structure probes. I will talk about some of the developments that make these simulations ideal for precision cosmology applications. As one such application, I will discuss how FLAMINGO sheds light on the coupling between cosmology and feedback from active galactic nuclei (AGN) and the resulting corrections to clustering statistics. I will also talk about the role simulations play in our effort to constrain the neutrino content of our Universe.
Remarks:	There are two talks. Seminar Room A + Zoom

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