Gravitational waves are a unique probe of the early Universe, as the Universe is transparent
to gravitational radiation right back to the end of inflation. This review summarizes detection …

Various pulsar timing array (PTA) experiments (NANOGrav, EPTA, PPTA, CPTA, including
data from InPTA) very recently reported evidence for excess red common-spectrum signals …

Composite topological structures such as superheavy “quasistable strings”(QSS) and “walls
bounded by strings”(WBS) arise in realistic extensions of the Standard Model of high energy …

Many symmetry breaking patterns in grand unified theories (GUTs) give rise to cosmic
strings that eventually decay when pairs of GUT monopoles spontaneously nucleate along …

Recently, Pulsar Timing Array (PTA) Collaborations have detected a stochastic gravitational
wave background (SGWB) at nano-Hz frequencies, with domain wall networks (DWs) …

In this paper, we analyse sound waves arising from a cosmic phase transition where the full
velocity profile is taken into account as an explanation for the gravitational wave spectrum …

We explore how quantum gravity effects, manifested through the breaking of discrete
symmetry responsible for both dark matter and domain walls, can have observational effects …

A series of pulsar timing arrays (PTAs) recently observed gravitational waves at the
nanohertz frequencies. Motivated by this remarkable result, we present a novel class of Pati …

Motivated by the NANOGrav 15 year data and other recent investigations of stochastic
gravitational background radiation based on pulsar timing arrays, we show how superheavy …

A bstract Light primordial black holes (PBHs) with masses smaller than 10 9 g (10− 24 M⊙)
evaporate before the onset of Big-Bang nucleosynthesis, rendering their detection rather …