Speaker
Description
High-frequency gravitational waves (f\gtrsimf≳~MHz) are a smoking gun for the existence of exotic physics. In particular, GW backgrounds lying in the high-frequency would allow one to probe inflation, first-order phase transitions, topological defects and primordial black holes. The lack of current and future gravitational wave experiments sensitive at those frequencies leads to the need of employing different indirect techniques. Notably, one of the most promising one is constituted by graviton-photon conversions in magnetic fields. In this talk, I will discuss possible signature of gravitational wave conversions within astrophysical magnetic fields, focusing on the case Galactic B-fields. In this regard, I will illustrate how graviton-to-photon conversions may lead to unexpected imprints in gamma-ray observations in the range of frequencies f\sim10^{9}-10^{26}\,\Hz. Hence, the absence of any significant evidence for a diffuse photon flux induced by gravitational-wave conversions places stringent constraints on the gravitational-wave strain h_c
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