Black
holes are often described as voracious and monstrous, with sloppy eating habits
that cause X-rays to be coughed up and spat out willy nilly.
Pushing
the dietary analogy a bit further, scientists now say that regardless of where black holes dine, they have the
same culinary habits.
Supermassive
black holes, which anchor many galaxies, feed just like smaller
"stellar" black holes, the researchers announced last week. The
finding supports some implications of Einstein's relativity
theory that black holes of all sizes have similar properties.
The
conclusion comes from a large observing campaign of the spiral galaxy M81,
which is about 12 million light-years from Earth. In the center of M81 is a
black hole about 70 million times more massive than the sun. It pulls gas from
the central region of the galaxy inward at high speed.
Stellar
mass black holes typically weigh just a few solar masses and have a different
source of food. They pull gas from an orbiting companion star.
In
both cases, when black holes dine, material spirals inward and becomes
superheated, giving off X-rays and other forms of radiation.
Researchers
wondered if they'd have the same feeding mechanism. A study of the X-rays,
optical light and radio waves emitted from the jowls of both black hole
varieties suggests they do.
Scientists
used the Chandra X-ray Observatory and multiple ground-based telescopes to take
detailed observations of the huge black hole at the center of the M81 galaxy,
and compared these to observations of smaller black holes. They found that
while the total energy coming out of the massive black hole was larger, the relative
amounts of energy being emitted at different wavelengths — from radio to
infrared to X-ray light — were roughly the same.
"The
shape of the light curves looks very much the same," said researcher
Michael Nowak of MIT. "The only difference is the total energy coming out.
The characteristic energy of the matter and the speeds of the jets all seem to work
the same way. It's just that big black
holes have more matter."
Even
the material falling onto the black hole seems to travel at the same speed,
regardless of the black hole's size. But since a more massive black hole has a wider
event horizon, or distance within which matter cannot escape, it takes material
longer to fall in.
"Everything
around this huge black hole looks just the same except it's almost 10 million
times bigger," Nowak said.
The
findings help scientists understand how black holes work on a fundamental level.
"I
think what this is really doing is helping us see the connection between
different kinds of black holes," Nowak told SPACE.com. "The
more we can say that big and small black holes are analogous to each other, it
gives us a better idea to understand how black holes eat matter and eject
matter."
And
because large black holes are thought to play an important role in galaxy
formation and evolution, by learning more about black holes scientists can
better understand how galaxies came to be, he said.
The
findings will be detailed in the Astrophysical Journal.
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