Non-standard cosmology2020.03.05 18:25 - admin-bp4
Understanding of the origin of accelerated expansion of the Universe (known as dark energy problem) is one of the most important challenges in modern cosmology and in fundamental physics. Lacking clear theoretical guidance in this respect we need to understand and describe the dynamics of the Universe in the most accurate and precise way using currently available observational data. At present, standard candles - Supernovae Ia and standard rulers (BAO, CMB acoustic peaks) serve this purpose. However, in order to break degeneracies in various cosmological parameters (curvature, mass density parameter, neutrino mass, Hubble constant) and trying to be free from prior assumptions on cosmological model (typically LCDM model) one needs new probes, which are alternative and complementary to the standard ones.
In the department we are developing the following new cosmological probes: strong gravitational lensing systems combined with stellar kinematics (complementary to time-delay method), mili-arcsecond compact radio-sources hosting intermediate luminosity quasars, quasars observed in UV and X-rays calibrated as standard candles, cosmic chronometers (passively evolving galaxies), gravitational wave signals from inspiralling compact binaries as standard candles and lensed gravitational wave signals as multimessengers. We are also using and developing non-parametric reconstruction techniques of expansion history of the Universe and consistency tests for the assumptions like LCDM model or validity of Friedman-Lemaitre-Robertson-Walker metric. Our interests extend to local measurements of cosmic curvature and testing validity of General Relativity on cosmological scales or tests of Lorentz invariance with extragalactic sources.