I will discuss the covariant non-relativistic expansion of general relativity in powers of 1/c, using as an example the case of a compact perfect fluid matter source that can radiate gravitational waves. This is a well-studied scenario in the literature that is conventionally done by using the approach developed, amongst others, by Blanchet and Damour. This approach uses the harmonic gauge and...
The local geometry around a null geodesic in an arbitrary spacetime resembles the geometry of a plane wave (PW) spacetime at leading order. This idea is called the Penrose limit. Families of curves that stay within this local neighbourhood of the null geodesic can be thought of as being “ultrarelativistic” in some suitable sense, and their motion is largely determined by the structure of the...
As gravitational waves (GW) probe the strong field regime of gravity, they are an important tool for testing gravitational models. This requires an accurate description of the gravitational waveforms in modified gravity theories. In this work we focus on scalar Gauss Bonnet gravity (sGB), a promising extension of General Relativity (GR), to include finite size effects in the modelling of the...
We show that for the motion of elementary particles in vacuum metrics the DeWitt-Brehme equation can be reduced to the covariant form of the Landau-Lifshitz equation. Further we discuss the implications of this approach in the Schwarzschild and Kerr black hole metrics immersed into external uniform magnetic field. In the latter case one can observe energy gain of a radiating charged particle...
For many years, the idea that there may be more than three spatial dimensions in our universe has attracted people’s interest. The method by which extra dimensions are concealed, making spacetime essentially four-dimensional as far as known physics is concerned, is a key issue in multidimensional theories. Extra dimensions might be large or infinite, and they might then have consequences that...
I am interested in understanding radiation reaction(RR) and the post-Newtonian(PN) expansion in the presence of a cosmological constant. To this end, de Sitter spacetime provides a simple maximally symmetric background, where the in-in action that describes the RR can be computed. This in-in action has a natural interpretation through a 'doubled' static patch geometry associated with a...
Scalar-tensor theories are one of the long-standing alternatives to General Relativity (GR). These theories introduce an extra degree of freedom through a scalar field coupled to gravity, which affects the dynamics and internal composition of neutron stars. In this talk we use an effective field theory approach in order to describe an isolated body with size effects, characterised through the...
