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Astronomers are witnessing a spectacle never seen before in space: the awakening of a supermassive black hole at the center of a distant galaxy.
At the end of 2019 team astronomers spotted an otherwise inconspicuous galaxy called SDSS1335+0728, 300 million light-years away in the constellation Virgo. The Zwicky Transient Facility telescope at the Palomar Observatory in California automatically recorded the galaxy’s sudden jump in brightness.
With its extremely wide field of view, the camera scans the entire northern sky every two days, capturing data on celestial objects such as near-Earth asteroids as well as distant bright supernovae.
An interdisciplinary team of astronomers and engineers followed up on Zwicky’s observations using information from space and ground-based telescopes to see how the galaxy’s luminosity has changed over time.
To their surprise, the scientists realized that they had witnessed a unique moment when a cosmic monster had awakened. The results of their study have been accepted for publication in the journal Astronomy & Astrophysics.
“Imagine that you have observed a distant galaxy for years and it always seemed calm and inactive,” said study leader Paula Sánchez Sáez, an astronomer at the European Southern Observatory in Germany. “Suddenly it (the core) starts to show dramatic changes in brightness, unlike any typical events we’ve seen before.”
The team classified the galaxy as having an active galactic nucleus, or a bright compact region that is powered by a supermassive black hole.
A number of celestial scenarios can cause a galaxy to brighten suddenly, such as supernova explosions or when stars get too close to black holes and are torn apart during a phenomenon called a tidal disruption event.
But such events last only tens or hundreds of days — and SDSS1335+0728 continues to grow in brightness more than four years after scientists first observed the luminosity jump like a flick of a cosmic light switch.
And the brightness variations in the galaxy are unlike anything astronomers have seen before, which only confuses them even more.
To find answers, the team consulted archival data from NASA’s Wide-field Infrared Survey Explorer and Galaxy Evolution Explorer, the Two Micron All Sky Survey, the Sloan Digital Sky Survey, and other observatories.
The researchers compared the data with subsequent observations taken by the European Southern Observatory’s Very Large Telescope (VLT) in Chile, the Southern Astrophysical Research Telescope in Chile, the WM Keck Observatory in Hawaii, and NASA’s Neil Gehrels Swift and Chandra spacecraft. X-ray observatories.
Together, the datasets presented a broad portrait of the galaxy before and after the December 2019 observation, revealing that the galaxy has shifted in recent years to emit much more ultraviolet, visible and infrared light and X-rays since February – unprecedented. behavior, said Sánchez Sáez.
Since the galaxy is 300 million light-years away, the events astronomers see happened in the past—but the light from those events is just now hitting Earth after traveling through space for millions of years. One light year is the distance light travels in one year, which is 5.88 trillion miles (9.46 trillion kilometers).
“The most tangible possibility to explain this phenomenon is that we see the (core) of the galaxy starting to show (…) activity,” said study co-author Lorena Hernández GarcÃa, an astronomer at the Millennium Institute of Astrophysics and the University of ValparaÃso, both in Chile, in declaration. “If so, it would be the first time we’ve seen the activation of a massive black hole in real time.”
Supermassive black holes are classified as having masses over 100,000 times that of our Sun. They can be found at the center of most galaxies, including the Milky Way.
“These giant monsters are usually asleep and not directly visible,” study co-author Claudio Ricci, an associate professor at Diego Portales University in Chile, said in a statement. “In the case of SDSS1335+0728, we were able to observe the wake of a massive black hole, (which) suddenly began to feed on the gas available in its vicinity and became very bright.”
Previous research has pointed to inactive galaxies that appear to become active after a few years, which is usually triggered by black hole activity, but the black hole’s wake-up process has never been directly observed before, until now, Hernández GarcÃa said.
The same scenario may play out with Sagittarius A*, the supermassive black hole at the center of the Milky Way, but astronomers aren’t sure how likely it is to happen, Ricci said.
Astronomers cannot rule out that their sighting could be an unusually slow tidal disturbance or an unknown new celestial phenomenon.
“Regardless of the nature of the variations, (this galaxy) provides valuable information about how black holes grow and evolve,” Sánchez Sáez said. “We expect that instruments like (MUSE on the VLT or those on the upcoming Extremely Large Telescope) will be the key to understanding (why the galaxy brightens.”