Related papers: Some applications of the Shapiro time delay
This paper investigates the use of gravitational time delays of macro-lenses to constrain a possible photon mass. The time delay between the 2 compact images of a source of massive photons is computed. Explicit expressions are given for…
We study the effects of a finite mass for the photon on its propagation in a weak gravitational field. In particular, we analyse the gravitational time delay, also known as the Shapiro effect. We work in isotropic coordinates in the…
Propagation of relativistic particles in the Schwarzschild gravitational field is studied. Particles emitted radially outward with speed at infinity exceeding c/2^0.5 are observed to be accelerated in the gravitational field by a distant…
We discuss the deflection of light and Shapiro delay under the influence of gravity as described by Schwarzschild metric. We obtain an exact expression based on the coordinate velocity, as first set forth by Einstein, and present a…
We reexamined the gravitational time delay of light, allowing for various models of modified gravity. We clarify the dependence of the time delay (and induced frequency shift) on modified gravity models and investigate how to distinguish…
Although gravitational waves only interact weakly with matter, their propagation is affected by a gravitational potential. If a gravitational wave source is eclipsed by a star, measuring these perturbations provides a way to directly…
There has been a striking realization that physics resolving the black hole information paradox could imply postmerger gravitational wave echoes. We here report on evidence for echoes from the LIGO compact binary merger events, GW151226,…
The study of ultralight dark matter helps to constrain the lower bound of the mass in minimally coupled dark matter models. The granular structure of ultralight dark matter density fields produces metric perturbations which have been…
Gravitational waves are rapidly becoming a very reliable tool for testing alternative theories of gravity. In particular, features in the gravitational wave emission during black hole ringdown phase provide a direct probe of the spacetime…
Gravitational time delays, observed in strong lens systems where the variable background source is multiply-imaged by a massive galaxy in the foreground, provide direct measurements of cosmological distance that are very complementary to…
To determine whether the Shapiro time delay of light passing near a moving object depends on the ``speed of gravity'' or the ``speed of light,'' one must analyze observations in a bimetric framework in which these two speeds can be…
Can the observation of the "shadow" allow us to distinguish a black hole from a more exotic compact object? We study the motion of photons in a class of vacuum static axially-symmetric space-times that is continuously linked to the…
In the next decade or two, extremely accurate tests of general relativity under extreme conditions are expected from gravitational wave observations of binary black hole mergers with a wide range of mass ratios. In addition, major…
We consider the possibility that future wide-field time-domain optical imaging surveys may be able to discover gravitationally lensed quasar pairs through serendipitous measurements of their time delays. We discuss the merits such a…
The recent detection of gravitational waves has generated interest in alternatives to the black hole interpretation of sources. One set of such alternatives involves a prediction of gravitational wave "echoes". We consider two aspects of…
We discuss the implications for gravity wave detectors of a class of modified gravity theories which dispense with the need for dark matter. These models, which are known as Dark Matter Emulators, have the property that weak gravitational…
Space-time singularities, viz. Big bang, Big crunch and black holes have been shown to follow from the singularity theorems of General relativity. Whether the entropy at such infinite proper-time objects can be other than zero has also been…
One of the open questions of modern cosmology is the nature and properties of the Dark Matter halo and its substructures. In this work we study the gravitational effect of dark matter substructures on pulsar timing observations. Since…
Black Holes are unique objects which allow for meaningful theoretical studies of strong gravity and even quantum gravity effects. An infalling and a distant observer would have very different views on the structure of the world. However, a…
The possible detection of echoes in late gravitational-wave signals is the most promising way to test horizonless alternatives to general relativistic black holes, and probe the physics of these hypothetical ultra-compact objects. While…