Our galaxy’s supermassive black hole is relatively calm, but the center of the Milky Way galaxy, where it resides, is anything but a calm place. Its extreme locations are filled with acts that can best be described as shenanigans of epic proportions.
Now you can add a powerful cosmic accelerator known as PeVatron to Jape’s list. Astronomical observatories in the mountains of Mexico have recorded repeated emissions of some of the most energetic gamma rays ever recorded from a single point near the galactic center.
The nature of this water source, named HAWC J1746-2856, is unknown, but it is known as high-altitude water Cherenkov (hawk) The observatory recorded 98 gamma-ray events with energy levels exceeding 100 teraelectronvolts.
“These results provide a glimpse of orders of magnitude higher energies at the center of the Milky Way than we have ever seen before.” physicist Pat Harding says of Los Alamos National Laboratory.
“This study confirms for the first time that there is a PeVatron source of ultra-high energy gamma rays at a location in the Milky Way known as the galactic center ridge. This is because the galactic center is home to some of the most extreme physical processes in the universe. It means to exist.”
PeVatron is what you get when you mix cosmic rays (mainly charged protons and atomic nuclei flowing through space at nearly the speed of light) with a giant natural particle accelerator. Environments such as supernova remnants, nascent stars, and strong magnetic fields around supermassive black holes can become PeVatrons.
If particle accelerators are powerful enough, they can accelerate cosmic rays to extremely high energies, up to the tera-electronvolt range, or 1 trillion electronvolts.
Despite their power, finding such high-energy accelerators is not easy.
“Many of these processes are too rare to be expected to occur in our galaxy, or occur at scales that are uncorrelated to the size of the galaxy.” Harding explains. “For example, a black hole eating another black hole would be an event only expected outside our galaxy.”
When accelerated cosmic rays suddenly slow down due to interaction with something else in space, such as a magnetic field or a dust cloud, the energy they carry is released in the form of gamma rays.
gamma Radiation cannot travel far through the Earth’s atmosphere, so radiation cannot be detected directly from the ground.
But when they enter the atmosphere, their powerful energy is dispersed through interactions with other molecules, breaking them into a shower of harmless, low-energy particles. These can be detected using underground Cherenkov detectors like HAWC. Physicists can then reconstruct the gumIt can also reveal the rays that caused the showers, and even where in the sky they came from.
HAWC is particularly sensitive to tera-electronvolt energies and has made several breakthrough detections, including the first. TeV gamma rays from the sun.
A team led by University of Maryland physicist Sohyun Yu Cárcaron discovered signs of PeVatron in HAWC’s rich data collected over 2,546 days. And interestingly, 98 of these signals appear to come from the same point source at the center of the Milky Way.
The accelerator, named HAWC J1746-2856, spews out the most powerful radiation ever observed from the galactic center.
The research team has not yet narrowed down the identity of HAWC J1746-2856, and there are no known supernova remnants that match its source. There are two things in the vicinity that could be causing the release. It’s Sagittarius A*, the supermassive black hole around which the galaxy revolves. And a known but unidentified gamma-ray emitter called HESS J1746-285 is located near a galactic feature known as HESS J1746-285. radio arc.
Although researchers were unable to discern the nature of the source, their discovery confirmed the presence of Pevatron at the center of the galaxy.
The results tell us a few other things. For example, cosmic ray densities at the galactic center have been found to be higher than the galactic average, suggesting that this region contains a new source of accelerated protons.
But solving the strange mystery of HAWC J1746-2856 may have to wait for observations by the next generation of Cherenkov detectors.
This research Astrophysics Journal Letter.
