Cosmologie

Studying black hole populations with gravitational-wave observations

The first observations of gravitational waves emitted by merging binary black holes demonstrated the existence of black holes more massive than ever observed in our Galaxy. Future observations with ground-based interferometers such as Advanced LIGO and Virgo will probe the mass and spin distributions of black holes in various galactic environments and may also detect the stochastic gravitational-wave background from unresolved mergers. These measurements will provide a new tool for stellar and galaxy evolution studies.

Physics of Gravitational Redshifts in Clusters of Galaxies

Wojtak, Hansen and Hjorth and others have measured the long-predicted gravitational redshift of light escaping from galaxy clusters.  The effect is very small, corresponding to a velocity shift of only ~10 km/s, but the result appears to be fairly robust and seemed to be in good agreement with general relativity predictions and possibly in conflict with some alternative theories. The effect was initially imagined to be a simple astronomical analogue of the famous terrestrial Pound and Rebka experiment that verified Einstein's theoretical prediction.

The Dark Energy Survey Supernova Program and the Australian OzDES survey

The Dark Energy Survey (DES) is using four probes to investigate the dynamics of the expansion of the Universe. The DES Supernova Program (DES-SN) is observing 27 square degrees with a 6-day cadence to obtain a large sample of type Ia supernovae for cosmology. In collaboration with DES, OzDES is using the AAT to obtain redshifts and classifications for objects in the DES fields.

Probing dark energy with cosmic voids

Cosmic voids can supply powerful insights into the nature of dark energy, provided that we have accurate models of their statistical properties. In this talk I will present a new method to identify and predict void density profiles, and show how we can reduce systematic errors when probing the growth rate around voids. This will be crucial for testing non-standard dark energy models with upcoming large survey campaigns.

Possible consequences in Cosmology from the vector-like SU(3) family symmetry model

Extension of the Standard Model (SM) by gauged SU(3) symmetry of families involves new physics at high energy scales. Even elusive from direct experimental probes, such construction can be tested in the combination of Particle physics, Astrophysics and Cosmological signatures. We point out possible Cosmological impact of the new scalars, gauge bosons and vector-like quarks and leptons, including sterile neutrinos, of the vector-like SU(3) family symmetry.  

Robust but enigmatic post-Planck Cosmos

The widely heralded and remarkable   progress in cosmology 
leading to  the emergence of a  'standard cosmological model’ has relied on  
certain key assumptions at various levels.  I review work along  
multiple facets, largely,  from the research program of  my group 
at IUCAA, that have all attempted to adopt  an agnostic approach in 
drawing cosmological inference independent  of such assumptions, 
in the context of  the exquisite   observations  of the Cosmic  Microwave 
Background CMB anisotropy by Planck. I dwell on the enigmatic 

The Milky Way Dark Matter Halo and Direct Dark Matter Detection Results

Dark matter is ubiquitous. However, we do not know what it is. A large number of direct (and indirect detection) experiments, both ongoing and planned, are aimed at unveiling the particle nature of dark matter. All these searches take place within our own Milky Way halo and, thus, the Milky Way dark matter astrophysics is a crucial input. In this talk, I will review some current developments of our knowledge of the phase-space of our own dark matter halo and briefly show how it impacts particle physics dark matter searches.

 

Pages

S'abonner à RSS - Cosmologie