Complete Gravitational-Wave Spectrum of the Sun

The high-temperature plasma in the solar interior generates stochastic gravitational waves (GWs). Due to its significance as the primary source of high-frequency GWs in the solar system, we reexamine this phenomenon highlighting some physical processes, including the contribution of macroscopic hydrodynamic fluctuations. Our analysis builds upon several studies of axion emission from the Sun, particularly in relation to the treatment of plasma effects. The resulting GW spectrum is comparable to many well-motivated early Universe signals, yet orders of magnitude below the current sensitivities of axion helioscopes such as (Baby)IAXO.