Skip to main content

TAU-led team discovers new way black holes are “fed”

Written on |

These “giant monsters” were observed suddenly devouring gas in their surroundings

Supermassive black holes weigh millions to billions times more than our sun and lie at the center of most galaxies. A supermassive black hole several million times the mass of the sun is situated in the heart of our very own Milky Way.

Despite how commonplace supermassive black holes are, it remains unclear how they grow to such enormous proportions. Some black holes constantly swallow gas in their surroundings, some suddenly swallow whole stars. But neither theory independently explains how supermassive black holes can “switch on” so unexpectedly and keep growing so fast for a long period.

A new Tel Aviv University-led study published today in Nature Astronomy finds that some supermassive black holes are triggered to grow, suddenly devouring a large amount of gas in their surroundings.

Following the light

In February 2017, the All Sky Automated Survey for Supernovae discovered an event known as AT 2017bgt. This event was initially believed to be a “star swallowing” event, or a “tidal disruption” event, because the radiation emitted around the black hole grew more than 50 times brighter than what had been observed in 2004.

However, after extensive observations using a multitude of telescopes, a team of researchers led by Dr. Benny Trakhtenbrot and Dr. Iair Arcavi, both of TAU’s Raymond & Beverly Sackler School of Physics and Astronomy, concluded that AT 2017bgt represented a new way of “feeding” black holes.

“The sudden brightening of AT 2017bgt was reminiscent of a tidal disruption event,” says Dr. Trakhtenbrot. “But we quickly realized that this time there was something unusual. The first clue was an additional component of light, which had never been seen in tidal disruption events.”

Dr. Arcavi, who led the data collection, adds, “We followed this event for more than a year with telescopes on Earth and in space, and what we saw did not match anything we had seen before.”

The observations matched the theoretical predictions of another member of the research team, Prof. Hagai Netzer, also of Tel Aviv University.

“We had predicted back in the 1980s that a black hole swallowing gas from its surroundings could produce the elements of light seen here,” says Prof. Netzer. “This new result is the first time the process was seen in practice.”

Mysterious re-activation 

Astronomers from the U.S., Chile, Poland and the U.K. took part in the observations and analysis effort, which used three different space telescopes, including the new NICER telescope installed on board the International Space Station.

One of the ultraviolet images obtained during the data acquisition frenzy turned out to be the millionth image taken by the Neil Gehrels Swift Observatory — an event celebrated by NASA, which operates this space mission.

The research team identified two additional recently reported events of black holes “switched on,” which share the same emission properties as AT 2017bgt. These three events form a new and tantalizing class of black hole re-activation.

“We are not yet sure about the cause of this dramatic and sudden enhancement in the black holes’ feeding rate,” concludes Dr. Trakhtenbrot. “There are many known ways to speed up the growth of giant black holes, but they typically happen during much longer timescales.”

“We hope to detect many more such events, and to follow them with several telescopes working in tandem,” says Dr. Arcavi. “This is the only way to complete our picture of black hole growth, to understand what speeds it up, and perhaps finally solve the mystery of how these giant monsters form.”

Related posts

Is the Heaviest Black Hole in Our Galaxy Closer Than We Think?

16 April 2024

First Israeli Nanosatellite Designed to Communicate from Space with Optical Ground Station

4 January 2023

Researchers Characterize Earliest Galaxies in the Universe

4 December 2022

Two New Planets Found in Milky Way

11 July 2022

Diagnosing Diseases in Space

6 July 2022

The “COTS-Capsule” that protects electronic systems from hazardous radiation effects in space

18 January 2022

For the 1st time at an Israeli university: Air and Space Power Center

5 January 2022

Out of This World

5 January 2022

When the stars aligned: A star in a distant galaxy blew up in a powerful explosion, solving an astronomical mystery from the 11th century

16 July 2021

What Disrupted A Giant Black Hole’s Feast?

11 August 2020

A new, revolutionary way to simplify complex scientific calculations

7 December 2019

Discovery of a binary star orbited by three planets

6 May 2019

Over 400 People Attend Launch of “Astronomy on Tap”

22 April 2019

Conversations in the Clean Room

14 February 2019

Victoria

Tok Corporate Centre, Level 1,
459 Toorak Road, Toorak VIC 3142
Phone: +61 3 9296 2065
Email: [email protected]

New South Wales

Level 22, Westfield Tower 2, 101 Grafton Street, Bondi Junction NSW 2022
Phone: +61 418 465 556
Email: [email protected]

Western Australia

P O Box 36, Claremont,
WA  6010
Phone: :+61 411 223 550
Email: [email protected]