Professor Tsevi Mazeh

TAU scientists help discover massive stellar black hole

An international team, including astronomers from Tel Aviv
University, has uncovered the most massive stellar black hole found to
date in a binary system.

Published in the prestigious journal
Nature, the research was conducted by an international team including
Professor Tsevi Mazeh, who is the director of the Sackler Institute of
Astronomy at Tel Aviv University and holds the Oren Family Chair of
Experimental Physics, and his Ph.D. student Avi Shporer.

newly-discovered black hole is about 16 times the mass of our sun and
located three million light-years away in a distant galaxy called
Messier 33. The finding is unique because the black hole, named M33
X-7, is associated with an unusually large companion star (its binary
pair), with a mass about 70 times the mass of our sun. The two objects
move one around the other in space once every 3.5 days in an
everlasting dance.

A stellar black hole is formed from the
collapse of the core of a massive star at the end of its life. The
collapse creates an intense gravitational force, where not even rays of
light can escape its gravitational pull, rendering the phenomenon
invisible. Matter transferred from the companion star into the black
hole falls into the hole’s gravitational attraction and emits X-ray
radiation that the astronomers have detected by using special

“Giant telescopes and satellites make it possible
for us to discover in space systems that seem to come from a
science-fiction film,” says Prof. Mazeh. “We are able to study black
holes whose existence we were able to imagine only thanks to Einstein’s
General Theory of Relativity.”

This new discovery raises all
sorts of questions about how massive black holes are formed. Prof.
Mazeh says that these questions illustrate the enormous scale of the
universe and the smallness of the Earth within it. “I hope these
discoveries will lead scientists and even human society to a degree of
modesty,” he noted.

The scientific community has known about
black holes orbiting companion stars for 40 years. “This discovery
raises doubts about theories of how black holes, like this one, are
created,” said Prof. Jerome Orosz from San Diego State University, the
first contributor of the article. Prof. Orosz led the international
teams that analyzed data collected by the Chandra X-ray satellite and
the Gemini telescope in Hawaii.

Concludes Prof. Mazeh,
“Astronomical measurements allow us to peek into the vastness of space
and discover epic events incomparable with anything which takes place
on earth.”


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