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

Seahorses – Slow, but Fierce

October 6, 2021

Why Do We Squabble Over The AC?

October 5, 2021

A House is Not a Home Without a Pet

October 4, 2021

Fighting Pollution With Seaweed

September 12, 2021

Where Have All the Birds Gone?

August 11, 2021

Diminishing at the Edges

August 3, 2021

This Exhibition Will Make You Sweat

August 2, 2021

He’s Bringing Plastic Back

August 2, 2021

Tel Aviv Bats Have More Fun

July 22, 2021

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

July 15, 2021

Care for A Glass of Tel Aviv Air?

June 24, 2021

We Are Part of the Problem and the Solution

June 10, 2021

Bats ‘Social Distance’ Too

June 6, 2021

Time Flies and So Do Bats

May 31, 2021

When One Becomes Three

May 19, 2021

Our Planet in the Hands of Academia

May 12, 2021

Fireflies’ Protective ‘Musical Armor’ Against Bats

May 12, 2021

An Underwater Salute to Grandma Vera

April 8, 2021

Struggling in a Toxic Workplace?

April 6, 2021

Robot “Hears” through the Ear of a Locust

March 4, 2021

Tel Aviv’s Ecological Oasis: The Yehuda Naftali Botanic Garden at TAU

January 31, 2021

New Study Presents A Gloomy Climate Future for the Middle East

January 21, 2021

An Underwater Journey Following the Vanishing of Sponge Species from the Shallow Water of the Israeli Coast

December 1, 2020

Why Do Bats Fly Into Walls?

November 10, 2020

Prince of Monaco to TAU: Together, We Can Fix Environment

October 1, 2020

Pharmaceutical residuals pose a serious threat to Marine life

August 19, 2020

What Disrupted A Giant Black Hole’s Feast?

August 10, 2020

Bats navigate just like humans – using their excellent eyesight and a cognitive map

July 12, 2020

Turning vapor into electricity?

June 8, 2020

Rethinking our plan(e)t

February 19, 2020

Pope welcomes Israeli, Jordanian, Palestinian bird experts

June 11, 2019

Discovery of a binary star orbited by three planets

May 6, 2019

Over 400 People Attend Launch of “Astronomy on Tap”

April 22, 2019

Inside a bat’s brain

February 13, 2019

Conversations in the Clean Room

February 13, 2019

Inside a bat’s brain

February 13, 2019

Pursuing the Unknown

Copyright ©  Tel Aviv University Trust. All rights reserved.
Registered charity number 314179.