The recent detection of a stochastic signal in the NANOGrav 15-year dataset has aroused
great interest in uncovering its origin. However, the evidence for the Hellings-Downs …

General relativity predicts that gravitational waves propagate at the speed of light. Although
ground-based gravitational-wave detectors have successfully constrained the velocity of …

In the summer of 2023, the pulsar timing arrays (PTAs) announced a compelling evidence
for the existence of a nanohertz stochastic gravitational wave background (SGWB). Despite …

Gravitational waves (GWs) influence the arrival times of radio signals coming from pulsars.
Here, we investigate the harmonic space approach to describing a pulsar's response to …

Pulsar timing arrays (PTAs) have revealed galaxy-size gravitational waves (GWs) in the form
of a stochastic gravitational wave background (SGWB), correlating the radio pulses emitted …

Pulsar timing array (PTA) observations hinted towards the existence of a stochastic
gravitational wave background (SGWB) in the nHz frequency band. Still, the nature of the …

The recent compelling observation of the nanohertz stochastic gravitational wave
background has brought to light a new galactic arena to test gravity. In this paper, we derive …

Strong evidence for the Helling-Downs correlation curves have been reported by multiple
pulsar timing array (PTA) collaborations in the middle of 2023. In this work, we investigate …

There is growing interest in the overlap reduction function in pulsar timing array
observations as a probe of modified gravity. However, current approximations to the Hellings …

Astrometry, the precise measurement of star motions, offers an alternative avenue to
investigate low-frequency gravitational waves through the spatial deflection of photons …