Massive galaxy halo exposed with low density and magnetization.


Recently researchers encountered a massive galaxy halo due to Fast Radio Burst (FRB) detected by a radio interferometer.

The galaxy exposed has a sheath of cool halo gases that extend up to hundreds of kilo parsec.

Massive galaxy halo gases

  • These are the gases that surround the galaxy, which are supposed to serve as the reservoir for future stars.
  • The halo gas contains very low density and very faint magnetic field.
  • The density of these gases decides the light travelling time.

“This data can also be used to infer gas density, with most estimates on high side” Prochaska continues, ”Our new measurements on a single galaxy with this FRB observation have given a density and magnetic field strength which are both lower than previous estimates”.

Fast radio burst (FRB)

This can be defined as a probe to detect the galaxies with the help of lightening of the burst.

FRB was discovered in Nov 2018 designated as FRB 181112. It was initially observed and localized by Australian Square Array Path Finder (ASKAP) radio telescope.

This probe not only helped in detecting its native galaxy from which it emerged, but also helped in identification of the galaxy in front along the line of sight.

“The signal from the fast radio burst exposed the nature of magnetic field around the galaxy and the structure of halo gas” Professor Prochaska.

“When the team overlaid the radio and optic images they were able to determine that FRB 181112 penetrated the galactic halo foreground galaxy providing for the first time, a direct way to investigate the matter that is for all purpose, invisible” adds Cherie Day of Swinburne University.

How to detect the galaxy with radio burst

There is an explosion that lasts for millisecond and that particular explosion or burst helps to detect the galaxy. A recent study was made by University of California, Santa Cruz, the researchers use FRB to detect the galaxies surrounded by halo gases that even comprises of dark matter.

These halo gases are still mystery to be solved as these are invisible to eyes.

“The primary challenge is the gas, which has to diffuse to emit light brightly” J. Xavier Prochaska Prof. of Astronomy and Astrophysics at University of California, Santa Cruz. “With a few exceptions halo gas is invisible even to our largest telescope”.

Generally all signals of FRB 181112 consists of lightening that lasts for 40 microsecond, the maximum limit of this duration entirely depends on the density of the halo gases. Because dense medium would increase the light travelling time, as it is difficult for light to pass through denser medium rather than rarer medium.

These fluctuations in the lightning variability or pulse time indicates the density of halo gases being very less dense, less than one- tenth per cubic cm.

“One favored model is that halos are pervaded by clouds of clumsy gas” says Prochaska “but we have found no evidence of these clouds whatsoever”.

Prochaska points “This galaxy may be special. We will need to use FRBs to study tens or hundreds of galaxies over a range of masses and ages to assess the full population”.

FRB 181112 indicate that magnetic field of halo is super weak, to compare weaker than the refrigerator magnets.

“The study proves a new transformation for exploring the nature of galaxy halos”. By Prochaska.