GravitationalWaves

Stochastic gravitational wave background (SGWB) is expected to be more promising at this aim. Since many years, the proposers study the generation of a SGWB signal by a primordial magnetic field #1 #2 #3 #4. However, this has been carried on mainly in the spirit of using this observable to constrain the primordial magnetic field amplitude. Now that the era of GW astronomy and cosmology has started, it is timely to reconsider this topic in depth, with the aim of establishing to which level the planned next generation of GW detectors, both Earth-based and space-based, can constrain or detect the presence of a primordial magnetic field. In this context, the space-based interferometer LISA, which has been approved by ESA and is scheduled for mission adoption in 2023, is particularly interesting. The frequency range of LISA spans from 10-5 to 0.1 Hz. In the early universe, this corresponds to processes operating around the TeV energy scale. LISA could therefore probe the SGWB signal from a magnetic field generated during the Electroweak Phase Transition, which is an important candidate among primordial magnetogenesis scenarios (c.f. discussion in #5 and references therein).

References:

#1 C. Caprini et al., JCAP 0912 (2009) 024.

#2 C. Caprini et al., JCAP 0911 (2009) 001.

#3 C. Caprini and R. Durrer, Phys.Rev. D65 (2001) 023517 .

#4 C. Caprini et al., Phys.Rev. D69 (2004) 063006.

#5 K.Subramanian, Rep.Progr.Phys. 79 (2016) 076901 .