The exploration of the universe has recently entered a new era thanks to the multi-
messenger paradigm, characterized by a continuous increase in the quantity and quality of …

Gravitational waves (GWs) were recently detected for the first time. This revolutionary
discovery opens a new way of learning about particle physics through GWs from first-order …

Pulsar timing arrays aim to detect nanohertz-frequency gravitational waves (GWs). A
background of GWs modulates pulsar arrival times and manifests as a stochastic process …

We present observations and timing analyses of 68 millisecond pulsars (MSPs) comprising
the 15 yr data set of the North American Nanohertz Observatory for Gravitational Waves …

We searched for an isotropic stochastic gravitational wave background in the second data
release of the International Pulsar Timing Array, a global collaboration synthesizing decadal …

The noise in millisecond pulsar (MSP) timing data can include contributions from observing
instruments, the interstellar medium, the solar wind, solar system ephemeris errors, and the …

Abstract The North American Nanohertz Observatory for Gravitational Waves (NANOGrav)
has reported evidence for the presence of an isotropic nanohertz gravitational-wave …

Gravitational wave (GW) detection in space probes the GW spectrum that is inaccessible
from the Earth. In addition to the LISA project led by the European Space Agency, and the …

Multiple pulsar timing array (PTA) collaborations recently announced the evidence of
common-spectral processes caused by gravitational waves (GWs). These can be the …

We revisit the possibility that the stochastic common-spectrum process recently detected by
the NANOGrav pulsar timing array experiment could be due to primordial gravitational …