Group Events

Sunny Vagnozzi

"Recent developments in neutrino cosmology"

Special Seminar

CANCELED

Postponed 

Giorgia

Tamas

"Void size function" https://arxiv.org/pdf/1902.04585.pdf 

"Halo Mass function" https://arxiv.org/pdf/1903.01709.pdf 

International Woman's Day, suggested reading 

https://arxiv.org/abs/1811.11836 

"An alternative approach to the Finger of God in large scale structures" 

https://arxiv.org/abs/1810.01803 

"Counts-in-cells statistics for large-scale structure"

Special Seminal

"Fisher matrix for multiple tracers: model independent constraints on the redshift distortion parameter" https://arxiv.org/abs/1904.00673

 Briefly going through https://arxiv.org/abs/1905.08329

"Weak lensing by voids as a test for alternative cosmological models”

The accelerated expansion of our Universe is a long-standing problem in cosmology. Alternative theories of gravity offer a possible solution, but they are hard to constrain on small scales due to screening mechanisms that hide deviations from General Relativity. Cosmic voids are powerful probes of these theories, due to their underdense nature. We use a variety of void finding algorithms on mock galaxy catalogues that match the clustering constraints of current surveys. Our results show that weak gravitational lensing produced by voids will prove useful to constrain modified gravity models in forthcoming projects, such as LSST and EUCLID.

Special Seminal

"A non-fiducial cosmological test from geometrical and dynamical distortions around voids"

One of the major challenges of modern cosmology is to understand the nature of dark energy, which drives cosmic acceleration. Since their discovery, cosmic voids have been recognized as powerful cosmological laboratories, specially with the advent of modern galaxy redshift surveys. I will present a new cosmological test using the distribution of galaxies around cosmic voids without assuming a fiducial cosmology. The test is based on a physical model for the void–galaxy cross-correlation function projected along and perpendicular to the line of sight. We treat correlations in terms of void-centric angular distances and redshift differences between void–galaxy pairs, hence it is not necessary to assume a fiducial cosmology. This model reproduces the coupled dynamical (Kaiser effect, RSD) and geometrical (Alcock–Paczynski effect, GD) distortions that affect the correlation measurements. It also takes into account the scale mixing due to the projection ranges in both directions. The model is general, so it can be applied to an arbitrary binning scheme, not only in the case of the projected correlations. It primarily depends on two cosmological parameters: the matter fraction of the Universe today (sensitive to GD), and the ratio between the growth rate factor of density perturbations and the tracer bias (sensitive to RSD).