University of California, Santa Cruz | 2019 Sep 26
Analysis of radio pulses that passed through a galactic halo reveals a surprisingly quiescent halo with very low density and weak magnetic field
Using one cosmic mystery to probe another, astronomers have analyzed the signal from a fast radio burst, an enigmatic blast of cosmic radio waves lasting less than a millisecond, to characterize the diffuse gas in the halo of a massive galaxy.
A vast halo of low-density gas extends far beyond the luminous part of a galaxy where the stars are concentrated. Although this hot, diffuse gas makes up more of a galaxy’s mass than stars do, it is nearly impossible to see. In November 2018, astronomers detected a fast radio burst that passed through the halo of a massive galaxy on its way toward Earth, allowing them for the first time to get clues to the nature of the halo gas from an elusive radio signal.
“The signal from the fast radio burst exposed the nature of the magnetic field around the galaxy and the structure of the halo gas. The study proves a new and transformative technique for exploring the nature of galaxy halos,” said J. Xavier Prochaska ...
“When we overlaid the radio and optical images, we could see straight away that the fast radio burst pierced the halo of this coincident foreground galaxy and, for the first time, we had a direct way of investigating this otherwise invisible matter surrounding this galaxy,” said coauthor Cherie Day ...
Galaxy Surrounded by a Halo of Tranquil Gas
International Center for Radio Astronomy Research (ICRAR) | 2019 Sep 26
Enigmatic Radio Burst Illuminates a Galaxy's Tranquil Halo
ESO Science Release | 2019 Sep 26
The Low Density and Magnetization of a Massive Galaxy Halo
Exposed by a Fast Radio Burst ~ J. Xavier Prochaska et al
- Science (online 26 Sep 2019) DOI: 10.1126/science.aay0073 (pdf)