New insights on the cosmic strings stochastic gravitational wave background

In less than two years, GW detections have confirmed the omnipresence of black holes in the Universe and have shed lights on the origin of short
gamma ray bursts and kilonovae. What's next? Cosmic strings are one the expected outcome of phase transitions in the Early Universe. They have unique signatures in terms of GWs that strongly depend on various properties associated with the loops they produce, but not only. In this talk, after having reviewed the cosmological properties of a cosmic string network, I'll discuss a new estimate of the stochastic gravitational wave spectrum generated by a string network, including various effects neglected so far. In particular, for some string tensions, the signal ends up be boosted in
the LIGO and VIRGO frequency range and these are already constrained. The stochastic GW background is a new window to search for cosmic
strings, which encompasses the complete range of possible GUT phase transitions. Such a situation has never occurred before.