Abstract The Laser Interferometer Space Antenna (LISA) has two scientific objectives of
cosmological focus: to probe the expansion rate of the universe, and to understand …

We provide a review on the state-of-the-art of gravitational waves induced by primordial
fluctuations, so-called induced gravitational waves. We present the intuitive physics behind …

We report multiple lines of evidence for a stochastic signal that is correlated among 67
pulsars from the 15 yr pulsar timing data set collected by the North American Nanohertz …

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 …

We present results from the search for a stochastic gravitational-wave background (GWB) as
predicted by the theory of General Relativity using six radio millisecond pulsars from the …

Evidence for a low-frequency stochastic gravitational-wave background has recently been
reported based on analyses of pulsar timing array data. The most likely source of such a …

We search for an isotropic stochastic gravitational-wave background (GWB) in the 12.5 yr
pulsar-timing data set collected by the North American Nanohertz Observatory for …

The NANOGrav Collaboration has recently published strong evidence for a stochastic
common-spectrum process that may be interpreted as a stochastic gravitational wave …

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO
and Virgo full O3 dataset. Search results are presented for gravitational waves produced by …

ABSTRACT The International Pulsar Timing Array 2nd data release is the combination of
data sets from worldwide collaborations. In this study, we search for continuous waves …