Just usual business for the Hubble Space Telescope, as it captured more stunning images from across the galaxy for the Earthlings to marvel upon. This time, the telescope captured the ‘ghosts’ of eight quasars tens of thousands of light-years away whose light faded a long time ago.
Hubble photographed the images of eight unusual gas-cloud structures which were illuminated by the powerful radiation coming from a quasar – the most luminous known object in the universe. According to the scientists who analyzed the images, this suggests the past presence of bright quasars in their vicinity.
“Quasars are not bright enough now to account for what we’re seeing; this is a record of something that happened in the past,” Dr. Bill Keel with the University of Alabama, Tuscaloosa, concluded.
Quasars are immense luminous galactic cores formed around supermassive black holes. Each of the eight faded quasars used to orbit their host galaxy – NGC 5972, NGC 5252, Mrk 1498, UGC 11185, UGC 7342, the Teacup (also known as 2MASX J14302986+1339117), 2MASX J15100402+0740370, and 2MASX J22014163+1151237.
As the black hole absorbs all galactic material found within its reach – propelling it a very high speed towards its accretion disk – gas and dust heat up reaching incredibly high temperatures. This phenomenon results in the formation of the brilliant objects named quasars, blasting high-energy radiation all around the black hole’s disk.
What Hubble photographed is a collection of actually invisible space objects that became illuminated after they came in contact with the powerful jets of radiation emanating from the quasar. “In each of these eight images, a quasar beam has caused once-invisible filaments in deep space to glow through a process called photoionization,” European Space Agency officials explained. The ESA partnered up with NASA overseeing the Hubble project.
Photoionization happens when oxygen, sulphur, helium, nitrogen and neon atoms begin to re-emit the light they absorbed from the pulsating quasar. According to the scientists the stunning green light Hubble captured in these recent photos represents ionized particles of oxygen, which tend to glow in an emerald light.
However, researchers also concluded that the quasars lighting up the eight gas formation are long dead. They estimate the gas clouds are too far off the center of their host galaxies, thus suggesting it took several thousands of years for the quasar’s radiation to reach them.
In regard to the gas conglomerates themselves, ESA officials believe they were formed as a result of violent galactic mergers. “Galactic mergers do not just alter the forms of the previously serene galaxies involved; they also trigger extreme cosmic phenomena,” the ESA press release stated. A similar galactic merger could have also led to the formation of the quasars, scientists say.
The space agency is eager to reward people who saw the illuminated gas formation prior to their caption on Hubble images. For example, one glowing green space was named “Hanny’s Voorwerp” (the Dutch word for ‘object’) honoring schoolteacher Hanny van Arkel who first spotted the gas cloud in 2007.
Image Source: Sci News
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