# Hypermagnetic knots and gravitational radiation at intermediate frequencies

## TL;DR

This paper investigates how hypermagnetic knots at the electroweak epoch could generate a detectable stochastic gravitational wave background at intermediate frequencies, with potential implications for baryogenesis models and future gravitational wave observations.

## Contribution

It constructs a physical template for gravitational waves from hypermagnetic knots and analyzes their detectability and implications for baryogenesis and cosmology.

## Key findings

- Hypermagnetic knots can produce gravitational waves exceeding inflationary signals by nine orders of magnitude.
- The gravitational wave background from hypermagnetic knots is polarized, aiding potential detection.
- Lack of observed signals at intermediate frequencies could challenge certain baryogenesis models.

## Abstract

The maximally gyrotropic configurations of the hypermagnetic field at the electroweak epoch can induce a stochastic background of relic gravitational waves with comoving frequencies ranging from the $\mu$Hz to the kHz. Using two complementary approaches we construct a physical template family for the emission of the gravitational radiation produced by the hypermagnetic knots. The current constraints and the presumed sensitivities of the advanced wide-band interferometers (both terrestrial and space-borne) are combined to infer that the lack of observations at intermediate frequencies may invalidate the premise of baryogenesis models based (directly or indirectly) on the presence of gyrotropic configurations of the hypermagnetic field at the electroweak epoch. Over the intermediate frequency range the spectral energy density of the gravitational waves emitted by the hypermagnetic knots at the electroweak scale can exceed the inflationary signal even by nine orders of magnitude without affecting the standard bounds applicable on the stochastic backgrounds of gravitational radiation. The signal of hypermagnetic knots can be disambiguated, at least in principle, since the the produced gravitational waves are polarized.