Astronomers watch a supermassive black hole wake up in real time

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Astronomers are witnessing a spectacle never before seen in the universe: the awakening of a supermassive black hole at the center of a distant galaxy.

In late 2019, Team of Astronomers have noticed an unremarkable galaxy called SDSS1335+0728, located 300 million light-years away in the constellation Virgo. A sudden spike in the galaxy's brightness was detected spontaneously by the Zwicky Transient Facility telescope at Palomar Observatory in California.

Thanks to 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 bright distant supernovae.

An interdisciplinary team of astronomers and engineers followed up on Zwicky's observation using information from space-based and ground-based telescopes to see how the galaxy's luminosity has changed over time.

To their surprise, the researchers realized that they were witnessing a unique moment with the awakening of a cosmic monster. The results of their study have been accepted for publication in the Journal of Astronomy and Astrophysics.

“Imagine you have been observing a distant galaxy for years, and it has always seemed quiet and inactive,” lead study author Paula Sanchez Saez, an astronomer at the European Southern Observatory in Germany, said in a statement. “Suddenly, (its core) began to show dramatic changes in brightness, unlike any typical events we have seen before.”

The team classified the galaxy as containing an active galactic nucleus, or a bright, compact region feeding on a supermassive black hole.

A number of celestial scenarios can cause a galaxy to suddenly brighten, such as supernova explosions or when stars get too close to black holes and get torn apart during phenomena called tidal disturbance events.

But such events only last tens or hundreds of days, and SDSS1335+0728 continues to grow in brightness more than four years after researchers first noticed its brightness rising like the flick of a cosmic light switch.

The brightness variations in the galaxy are unlike anything astronomers have seen before, which has added to their confusion.

To find answers, the team reviewed archival data from NASA's Wide Field Infrared Survey Explorer, the Galaxy Evolution Explorer, the 2 Micron All-Sky Survey, the Sloan Digital Sky Survey and other observatories.

The researchers compared the data with follow-up observations made by the European Southern Observatory's Very Large Telescope, or VLT, in Chile, the Southern Astrophysical Research Telescope in Chile, the W.M. Keck Observatory in Hawaii, and NASA's Neil Girls-Swift and Chandra Space Observatory. X-ray observatories.

Together, the datasets provided a broad picture of the galaxy before and after the December 2019 observation, revealing that the galaxy had shifted to emit more ultraviolet, visible and infrared light in recent years, and X-rays starting in February – something unprecedented. behavior, Sanchez Saez said.

Given that the galaxy is 300 million light-years away, the events that astronomers see occurred in the past, but the light from these events is now reaching Earth after traveling through space for millions of years. One light year is The distance light travels in one yearthat 5.88 trillion miles (9.46 trillion km).

“The most obvious option to explain this phenomenon is that we see how the (core) of the galaxy began to show (…) activity,” said study co-author Lorena Hernandez Garcia, an astronomer at the Millennium Institute for Astrophysics and Columbia University. Valparaiso, both in Chile, in a statement. “If so, this would be the first time we have seen a massive black hole activate in real time.”

Supermassive black holes are classified as having masses 100,000 times greater than the mass of our Sun. It can be found at the center of most galaxies, including the Milky Way.

“These giant monsters are usually dormant and not directly visible,” Claudio Ricci, study co-author and assistant professor at Diego Portales University in Chile, said in a statement. “In the case of SDSS1335+0728, we were able to observe the awakening of the supermassive black hole, (which) suddenly started feeding on the gas available in its surroundings, and became extremely bright.”

Previous research has pointed to inactive galaxies that appear to become active after several years, which are usually stimulated by black hole activity, but the process of black hole awakening has never been observed directly before, until now, Hernandez-Garcia said.

Ritchie said the same scenario could happen with the supermassive black hole at the center of the Milky Way galaxy, Sagittarius A*, but astronomers aren't sure how likely that is.

Astronomers cannot rule out that their observation is an unusually slow tidal disturbance event, or a new, unknown celestial phenomenon.

“Regardless of the nature of the differences, (this galaxy) provides valuable information about how black holes grow and evolve,” Sanchez Saez said. “We expect that instruments like MUSE on the VLT or the one on the upcoming Very Large Telescope will be key to understanding why the galaxy is bright.”