An international team of astronomers has measured the magnetic field of a star-forming galaxy nearly 4.6 billion light-years away.
The galaxy in question is a star-forming disk galaxy that acts as a gravitational lens in the lensing system CLASS B1152+199.
The galaxy is at a redshift of 0.439, putting it about 4.6 billion years in the past.
It lies directly between a more-distant quasar and Earth, and its strong gravity splits the quasar’s image into two separate images. Importantly, the radio waves coming from this quasar, nearly 7.9 billion light-years away, are preferentially aligned, or polarized.
“The polarization of the waves coming from the background quasar, combined with the fact that the waves producing the two lensed images traveled through different parts of the intervening galaxy, allowed us to learn some important facts about the galaxy’s magnetic field,” explained lead author Dr. Sui Ann Mao, of the Max Planck Institute for Radio Astronomy in Bonn, Germany.
According to astronomers, galaxies have their own magnetic fields, but they are incredibly weak — a million times weaker than the Earth’s magnetic field.
One theory suggests that the magnetic field of a young galaxy starts off weak and tangled, becoming stronger and more organized over time.
But, because the magnetic field of the observed galaxy is not much different from the fields scientists observe in our own Milky Way Galaxy and nearby galaxies, the detection is evidence that galactic magnetism appears relatively early, rather than growing slowly over time.
“This means that magnetism is generated very early in a galaxy’s life by natural processes, and thus that almost every heavenly body…