Dark matter and Gravitational waves: Distinguishing Lambda CDM model from modified gravity

In this talk, I will discuss the two apparently distinct issues of dark matter and polarization modes of gravitational waves (GWs) in the framework of modified gravity. Both of these two phenomena have been extensively investigated within the so-called standard Lambda CDM model. At the same time, it is known that scalar degree of freedom caused by modifying the geometric part of action reveals a minimally coupled scalar field in the Einstein frame.

The focus of the talk would be to outline the reincarnation of scalaron as dark matter and possible screening of the scalar modes of GWs polarization in an f(R) model. This may lead to a case for settling score towards a viable model of the universe.