To truly understand the universe we need to look at it in every wavelength, and sometimes that requires some inventive methods. The High Altitude Water Cherenkov (HAWC) observatory in Puebla, Mexico is one such example, and it’s helping scientists to look at the universe in gamma rays.
The HAWC observatory has just released its first sky map, which shows pulsars, supernova remnants, and even flickering black holes. It is sensitive to photons with energies up to 100 teraelectronvolts (TeV), which is over 7 times the energy reached by the particles in the Large Hadron Collider.
“This is our deepest look at two-thirds of the sky, as well as the highest energy photons we’ve ever seen from any source,” said Brenda Dingus, as reported by New Scientist. She presented the map at the American Physical Society meeting in Salt Lake City, Utah on April 18. “We’re at the high energy frontier.”
HAWC''s first gamma ray sky map. HWAC Collaboration
HAWC doesn't work like your conventional telescopes, though. Instead, it uses the Cherenkov radiation effect. HAWC is made up of 300 water tanks filled with 200,000 liters of pure water each, and each tank has detectors. Scientists then use Cherenkov light to reconstruct images from the distant universe.
When high energy photons interact with the atmosphere, they generate a shower of secondary particles. Those particles are the ones that reach the observatory. These particles are moving at almost the speed of light in a vacuum, but they are moving faster than the speed of light in water. So when they move through the water they emit blue light (the Cherenkov radiation), like a supersonic jet generates a sonic boom.
The observatory works 24 hours a day and can pick up the changes in brightness in many gamma-ray sources both in our galaxy and beyond. Thanks to this feature, the team was able to observe a flare from a galaxy called Markarian 501 more than 450 million light-years away.
Over the next five years, this observatory will provide more insight into the gamma-ray sky and supermassive black hole flares, maybe even observing flares from the center of the Milky Way itself.
[H/T: New Scientist]