Ultra-low-frequency electromagnetic waves as signals and special counterparts of gravitational waves (from binary mergers) having tensorial and possible nontensorial polarizations

Abstract

Gravitational waves (GWs, from binary merger) interacting with super-strong magnetic fields of the neutron star (in the same binary system), would lead to perturbed electromagnetic waves [EMWs, in the same frequencies of these GWs, partially in the ultra-low-frequency (ULF) band for the EMWs]. Such perturbed ULF-EMWs are not only the signals, but also a new type of special EM counterparts of the GWs (unlike usual EM counterparts of gamma-ray bursts, they have accurately the same start time to the GWs). Here, generation of the perturbed ULF-EMWs is investigated, and the strengths of their magnetic components are estimated to be around 10 −12 Tesla to 10 −17 Tesla at the Earth for various cases, which would be already within or approaching the sensitivity range of the cutting-edge technologies of the magnetometry. Especially, for the case that the neutron star in the binary is a magnetar, the strengths of signals with level of ∼ 10 −13 to ∼ 10 −15 Tesla are already detectable by current highly sensitive ULF detectors and magnetometers. Waveforms of the perturbed ULF-EMWs will be modified into shapes different but related to the waveforms of the GWs, due to the amplification process during the binary mergers which could amplify the magnetic fields into 10 12 Tesla or even higher. Specific connection relationships between the polarizations of the perturbed ULF-EMWs and the polarizations (tensorial and possible nontensorial) of the GWs of binary mergers, are also addressed. These characteristic waveforms and particular polarizations of the perturbed ULF-EMWs will be very helpful for filtering and extracting the signals from background noise. Briefly, we propose such a potential novel way of detection for signals and special EM counterparts of the GWs from binary mergers, which would bring us some different new information of fundamental properties of the gravity and Universe that other GW detections may not provide.