Related papers: Radio Tests of GR
We study the impact of relativistic gravitational deflection of light on the accuracy of future Space Interferometry Mission (SIM). We estimate the deflection angles caused by the monopole, quadrupole and octupole components of…
In this work, our focus is on exploring the potential of current GRB measurements to provide reliable constraints on cosmological model parameters at high redshift. This work is divided into two parts. First, we calibrate the Amati relation…
The upcoming direct detection of gravitational waves will open a window to probing the strong-field regime of general relativity (GR). As a consequence, waveforms that include the presence of deviations from GR have been developed (e.g. in…
Gamma-ray bursts (GRBs) are extremely energetic events at cosmological distances. They provide unique laboratory to investigate fundamental physical processes under extreme conditions. Due to extreme luminosities, GRBs are detectable at…
We present the results of a second epoch of 18cm global Very Long-Baseline Interferometry (VLBI) observations, taken on 23 February 2001, of the central kiloparsec of the nearby starburst galaxy Messier 82. These observations further…
We use four observations with the European VLBI network to measure the first precise radio parallax of the Crab Pulsar. We found two in-beam extragalactic sources just outside the Crab Nebula, with one bright enough to use as a background…
The arrival of gravitational wave astronomy and a growing number of time-domain focused observatories are set to lead to a increasing number of detections of short gamma-ray bursts (GRBs) launched with a moderate inclination to Earth. Being…
During the last years, much attention has been paid to the astrometric implications of the galactic aberration in proper motions (GA). This effect causes systematic errors in astrometric measurements at a microarcsecond level. Some authors…
The detection of six Fast Radio Bursts (FRBs) has recently been reported. FRBs are short duration ($\sim$ 1 ms), highly dispersed radio pulses from astronomical sources. The physical interpretation for the FRBs remains unclear but is…
It is shown that the finite speed of gravity affects very-long baseline interferometric observations of quasars during the time of their line-of-sight close angular encounter with Jupiter. The next such event will take place in 2002,…
General relativity may be an effective theory with higher curvature correction terms in the action. Inclusion of these terms leads to exciting new possibilities, e.g., gravitational and electromagnetic perturbations following different…
We report astrometric results of VLBI phase-referencing observations of 22 GHz \hho\ masers emission toward the red hypergiant \vxsgr, one of most massive and luminous red hypergiant stars in our Galaxy, using the Very Long Baseline Array.…
Five compact radio sources, include 0420-014, 1334-127, 1504-166, 2243-123, and 2345-167, were observed at 5GHz by European VLBI (Very Long Baseline Interferometry) Network (EVN) in June, 1996. The primary purpose of this observation was to…
Lorentz-invariance violation (LV) at energy scales approaching the Planck regime serves as a critical probe for understanding quantum gravity phenomenology. Astrophysical observations of gamma-ray bursts (GRBs) present a promising avenue…
The asymmetry in the time delay for light rays propagating on opposite sides of a spinning body is analyzed. A frequency shift in the perceived signals is found. A practical procedure is proposed for evidencing the asymmetry, allowing for a…
In order to investigate the gravitational wave (GW) radiation, without appealing to the tensorial formalism of the linearized general relativity, we formulate the so-called modified linearized general relativity (MLGR). As an application of…
We calculate the time evolution of the flux, apparent size, and image centroid motion of gamma-ray burst (GRB) radio jets, and show that they can be resolved by the VLBA at distances of hundreds of Mpc. We find that GRB 030329 which showed…
The potential of gravitational lenses for providing direct, physical measurements of the Hubble constant, free from systematic errors associated with the traditional distance ladder, has long been recognized. However, it is only recently…
This work arose as an aftermath of Cassini's 2002 experiment \cite{bblipt03}, in which the PPN parameter $\gamma$ was measured with an accuracy $\sigma_\gamma = 2.3\times 10^{-5}$ and found consistent with the prediction $\gamma =1$ of…
We present the radio light curves of lensed images of the gravitational lens B1422+231. The observations have been carried out using the VLA at 8.4 and 15 GHz over a period of 197 days. We describe a method to estimate the time delay from…