Electromagnetic response to high-frequency gravitational waves having additional polarization states: distinguishing and probing tensor-mode, vector-mode and scalar-mode gravitons
Fang-Yu Li, Hao Wen, Zhen-Yun Fang, Di Li, Tong-Jie Zhang
Abstract
Abstract Gravitational waves (GWs) from extra dimensions, very early universe, and some high-energy astrophysical processes might have at most six polarization states: tensor- and nontensor-mode gravitons. The peak regions or partial peak regions (of the amplitudes or energy densities) of some of such GWs are just distributed in the GHz or higher frequency band, which would be an optimal frequency band for the electromagnetic (EM) response to such high-frequency GWs (HFGWs). In this paper we investigate the EM response to the HFGWs, and for the first time we obtain the concrete form of analytic solutions of the perturbative EM fields caused by all six possible polarizations of the HFGWs in the background stable EM fields and in the proposed three dimensional synchro-resonance system (3DSR system), respectively. It is found that all such six polarizations may in principle show separability and detectability. Moreover, the detection frequency band ( $$\sim 10^{8}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>8</mml:mn> </mml:msup> </mml:mrow> </mml:math> to $$10^{12}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>12</mml:mn> </mml:msup> </mml:math> Hz or higher) of the signal photon fluxes by the 3DSR system and the observation frequency range ( $$\sim 7\times 10^{7}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mn>7</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>7</mml:mn> </mml:msup> </mml:mrow> </mml:math> to $$3\times 10^{9}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>3</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>9</mml:mn> </mml:msup> </mml:mrow> </mml:math> Hz) of the signals by the FAST (Five-hundred-meter Aperture Spherical Telescope, China) have a certain overlapping property, and thus their coincidence experiments in the future for observations will have high complementarity.