Universal $10^{20}$Hz stochastic gravitational waves from photon spheres of black holes

Abstract

We show that photon spheres of supermassive black holes generate high-frequency stochastic gravitational waves through the photon-graviton conversion. Remarkably, the frequency is universally determined as me me/mp 10 20 Hz in terms of the proton mass mp and the electron mass me. It turns out that the density parameter of the stochastic gravitational waves Ωgw could be 10 −12 . Since the existence of the gravitational waves from photon spheres is robust, it is worth seeking methods of detecting high-frequency gravitational waves around 10 20 Hz.

Conversion of gravitational and electromagnetic waves without any external background field

“…Thus, the substantial conversion observed is attributed to the nonlinear dynamics resulting from the interaction between the waves. This result distinguishes our work from previous studies that examined similar conversion phenomena through perturbative approaches [16][17][18][19][20][21][22][23], and likely represents the first demonstration of large conversion phenomena driven entirely by "nonlinearity." In fact, a numerical relativistic approach had already been used to study the conversion phenomena [24].…”

“…The methodology employed in this study to construct a new set of metric and electromagnetic fields is as follows: Initially, we solve Eqs. (19) and (20) to find their solutions. Next, utilizing the definition (18), we algebraically determine the quantities e 2ψ , Φ, χ and A z .…”

Electromagnetic counterparts of high-frequency gravitational waves in a rotating laboratory frame system and their detection

“…Thus, how to detect continuous GWs and GWs in other frequency bands is of great significance and urgent affairs at present. In fact, many mainstream cosmological models, high-energy astrophysical processes, and even high-energy physical experiments have predicated the existence of the HFGWs in the GHz band even higher frequencies, and the corresponding amplitudes would be expected to be h ∼ 10 −23 to 10 −39 [2][3][4][5]. Obviously, such high frequencies are far beyond the detection ability of traditional ground-band GW detectors.…”

Conversion of gravitational and electromagnetic waves without any external background fields

“…several studies have been done to treat the occurrence of conversion phenomena based on the existence of external background fields, such as electromagnetic fields around black holes [6][7][8][9][10][11].…”