Register for updates

 
 

Astronomy & Astrophysics
RSS Feed
TAU-Led International Team Discovers New Way Supermassive Black Holes Are "Fed"
Monday, January 14, 2019 12:09:00 PM

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.

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."

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."

Image caption: An artistic impression of a gas disk feeding a massive black hole while emitting radiation. (Credit: NASA)




Latest News

Study Finds Prehistoric Humans Ate Bone Marrow Like Canned Soup 400,000 Years Ago

Bone and skin preserved the nutritious marrow for later consumption, TAU researchers say.

TAU and Ichilov Researchers Develop Innovative Treatment for Familial Adenomatous Polyposis

Adolescents and young adults with the inherited disorder bear a high risk of developing colorectal cancer.

Engineered T Cells May Be Harnessed to Kill Solid Tumor Cells

Novel immunotherapy extends therapy now used in fighting leukemia, TAU researchers say.

Researchers Discover How a Protein Connecting Calcium and Plant Hormone Regulates Plant Growth

Mechanism enables plants to adapt their development to their environment, TAU researchers say.

LocalTAU Top Scientists Move Closer to Securing Pilot Program in Miami

Fellows from competition return to Miami to present at marine health summit and participate in high-level meetings.

TAU Researchers Discover Evidence of Biblical Kingdom of Edom in Arava Desert

Findings also suggest pharaoh's influence on Edom turned kingdom into copper powerhouse, say TAU researchers.

Business and Civic Leader Mort Mandel Awarded TAU Honorary Doctorate

Mr. Mandel cited for his visionary philanthropy and establishment of the Jack, Joseph and Morton Mandel Center for STEM and the Humanities at TAU.

Early Humans Used Tiny, Flint "Surgical" Tools to Butcher Elephants

New discovery by TAU-led research group suggests early humans in the Levant were sophisticated and environmentally conscious.

TAU Ranks Among Top 10 Undergraduate Programs Producing Most Venture Capital-Backed Entrepreneurs

Joining Stanford, UC Berkeley, and MIT, TAU is the only non-U.S. university to make top 10 of global VC list.

Protein Mapping Pinpoints Why Most Metastatic Melanoma Patients Do Not Respond to Immunotherapy

Lipid metabolism found to affect cancer cells' visibility to the immune system, say TAU, Sheba Medical Center researchers.

contentSecondary
c

© 2019 American Friends of Tel Aviv University
39 Broadway, Suite 1510 | New York, NY 10006 | 212.742.9070 | info@aftau.org
Privacy policy | Tel Aviv University