Helioseismology and Asteroseismology: Looking for Gravitational Waves in acoustic oscillations

Understand

Current helioseismology observations allow the determination of the frequencies and surface velocity amplitudes of solar acoustic modes with exceptionally high precision.

• In some cases, the frequency accuracy is better than one part in a million.
• We show that there is a distinct possibility that the quadrupole acoustic modes of low order could be excited by gravitational waves (GWs), if the GWs have a strain amplitude in the range $10^{-20}h_{-20}$ with $h_{-20}\sim 1$ or $h_{-20}\sim 10^{3}$, as predicted by several types of GW sources, such as galactic ultracompact binaries or extreme mass ratio inspirals and coalescence of black holes.
• If the damping rate at low order is $ 10^{-3}\eta_N$ $\mu{\rm Hz}$, with $\eta_N\sim 10^{-3} $ - $1,$ as inferred from the theory of stellar pulsations, then GW radiation will lead to a maximum rms surface velocity amplitude of quadrupole modes of the order of $h_{-20}\eta_N^{-1}\sim$ $10^{-9}$ - $10^{-3}$ ${\rm cm\; s^{-1}}$, on the verge of what is currently detectable via helioseismology.