There’s so much we don’t know about fast radio bursts and galactic halos. Combined, we get a unique window on the Universe.
Deep in space, mysterious signals known as Fast Radio Bursts (FRBs) stream towards Earth.
These FRBs last milliseconds or less, originate in ultra-distant galaxies, and sometimes repeat.
Although scientists have studied them intensely since their discovery, their origins remain mysterious.
Meanwhile, an estimated 2 trillion galaxies populate our observable Universe.
With incredibly large distances for FRBs to traverse, each one risks passing through an intervening galaxy.
Giving off multiple pulses of under 40 microseconds apiece, FRB 181112 became the first burst to intercept a galactic halo.
Halos are their own enigmas, populated with cool, enriched gas extending for hundreds of thousands of light-years.
This gas is necessary for fueling future star-formation, but its physical properties remain largely unexplored.
Absorption features previously revealed abundant, cool (~10,000 K), low-density gas in these halos.
But properties like total halo mass and hot (~1,000,000+ K) gas density are still undetermined.
When FRB 181112’s pulses traversed this galaxy’s halo, they were surprisingly unaffected.
This burst revealed a tranquil halo for this Milky Way-like galaxy, with:
- very low-density gas,
- no turbulence,
- no clumps,
- and negligible magnetization.
Are these properties universal to all Milky Way-like galaxies?
More observations, with additional FRBs, hold the answers.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.