Primordial Gravitational Wave Signals in Modified Cosmologies

Understand

Modified expansion rates in the early Universe prior to big bang nucleosynthesis are common in modified gravity theories, and can have a significant impact on the generation of dark matter, matter-antimatter asymmetry, primordial black holes and the primordial gravitational wave (PGW) spectrum.

• Here we study the PGW spectrum in modified gravity theories, in early Universe cosmology.
• In particular, we consider scalar-tensor and extradimensional scenarios, investigating the detection prospects in current and future GW observatories.
• For the scalar-tensor case, PGW could be potentially observed by laser interferometers operating in the high-frequency range, while for the extradimensional case they could be detected even at low frequencies with pulsar timing arrays.