A newly discovered galaxy is aiding astronomers in the research into the early evolution of individual galaxies and galaxy clusters. Named Speca, this unique finding is only the second spiral galaxy known to produce “jets” – streams of subatomic particles emitted from the nucleus. What’s more, it’s also one of two which shows this activity happened in separate intervals.
As astronomers know, galaxy jets are formed at the heart of activity where a supermassive black hole is present. While both elliptical and spiral galaxies have known supermassive black holes, only one had been known to produce copious amounts of material from its poles – Messier 87. Now Speca is changing the way researchers look for recurring activity.
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“This is probably the most exotic galaxy with a black hole ever seen. It has the potential to teach us new lessons about how galaxies and clusters of galaxies formed and developed into what we see today,” said Ananda Hota, of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), in Taiwan.
Located in a galaxy cluster about 1.7 billion light-years, Speca (an acronym for Spiral-host Episodic radio galaxy tracing Cluster Accretion) made its presence known to Ananda’s researches via an image which joined data from the visible-light Sloan Digital Sky Survey and the FIRST survey done with the National Science Foundation’s Very Large Array (VLA) radio telescope. Subsequent observations with the Lulin optical telescope in Taiwan and ultraviolet data from NASA’s GALEX satellite verified the lobes of material were part of an active, star-forming galaxy. Ananda’s team further refined their studies with information from the NRAO VLA Sky Survey (NVSS), then made new observations with the Giant Meterwave Radio Telescope (GMRT) in India. Each telescope set provided more and more clues to solving the puzzle.
“By using these multiple sets of data, we found clear evidence for three distinct epochs of jet activity,” Ananda explained. But the real excitement began when the low-frequency nature of the oldest, outermost lobes was examined. It was an artifact which should have disappeared with time.
“We think these old, relic lobes have been ‘re-lighted’ by shock waves from rapidly moving material falling into the cluster of galaxies as the cluster continues to accrete matter,” said Ananda. “All these phenomena combined in one galaxy make Speca and its neighbors a valuable laboratory for studying how galaxies and clusters evolved billions of years ago.”
Sandeep K. Sirothia of India’s National Centre for Radio Astrophysics, Tata Institute of Fundamental Research (NCRA-TIFR) said, “The ongoing low-frequency TIFR GMRT Sky Survey will find many more relic radio lobes of past black hole activity and energetic phenomena in clusters of galaxies like those we found in Speca.” Also, Govind Swarup of NCRA-TIFR, who is not part of the team, described the finding as “an outstanding discovery that is very important for cluster formation models and highlights the importance of sensitive observations at meter wavelengths provided by the GMRT.”
Stay close to your radio, folks… Who knows what we’ll hear in the future!
Original Story Source: National Radio Astronomy Observatory News.