This illustration shows a black hole that grew faster than its host galaxy.
Credit: Michael S. Helfenbein/Yale University
Astronomers have spotted a super-sized black hole in the early universe that grew much faster than its host galaxy.
The discovery runs counter to most observations about black holes,
which are massive areas of space with extraordinarily strong gravity
that can pull in anything -- even light. In most cases, black holes and
their host galaxies expand at the same rate.
This particular black hole formed in the early universe, roughly two
billion years after the Big Bang. An international research group made
the discovery during a project to map the growth of supermassive black
holes across cosmic time. The team included astronomers from Yale
University, ETH Zurich, the Max-Planck Institute in Germany, Harvard
University, the University of Hawaii, INAF-Osservatorio Astronomico di
Roma, and Oxford University.
"Our survey was designed to observe the average objects, not the
exotic ones," said C. Megan Urry, Yale's Israel Munson Professor of
Astrophysics and co-author of a study about the phenomenon in the
journal Science. "This project specifically targeted moderate
black holes that inhabit typical galaxies today. It was quite a shock to
see such a ginormous black hole in such a deep field."
Deep-field surveys are intended to look at faint galaxies; they point
at small areas of the sky for a longer period of time, meaning the
total volume of space being sampled is relatively small.
This particular black hole, located in the galaxy CID-947, is among
the most massive black holes ever found. It measures nearly 7 billion
solar masses (a solar mass is equivalent to the mass of our Sun).
However, it was the mass of the surrounding galaxy that most
surprised the research team. "The measurements correspond to the mass of
a typical galaxy," said lead author Benny Trakhtenbrot, a researcher at
ETH Zurich's Institute for Astronomy. "We therefore have a gigantic
black hole within a normal-size galaxy."
Most galaxies, including our own Milky Way, have a black hole at
their center, holding millions to billions of solar masses. Not only
does the new study challenge previous notions about the way host
galaxies grow in relation to black holes, it also challenges earlier
suggestions that the radiation emitted by expanding black holes curtails
the creation of stars.
Stars were still forming in CID-947, the researchers said, and the
galaxy could continue to grow. They said CID-947 could be a precursor of
the most extreme, massive systems observed in today's local universe,
such as the galaxy NGC 1277 in the Perseus constellation, 220 million
light years from the Milky Way. But if so, they said, the growth of the
black hole still greatly anticipated the growth of the surrounding
galaxy, contrary to what astronomers thought previously.
Urry and her colleagues credited the W.M. Keck Observatory in Hawaii
and the Chandra COSMOS legacy survey in aiding the team's work. "The
sensitivity and versatility of Keck's new infrared spectrometer,
MOSFIRE, was critical to this discovery," Urry said.
Other co-authors of the paper include Francesca Civano, an associate
research scientist at Yale; David Rosario, of the Max-Planck Institute;
Martin Elvis, of Harvard; Kevin Schawinski, of ETH Zurich and a former
Einstein Fellow at Yale; Hyewon Suh, of Harvard; Angela Bongiorno, of
INAF-Osservatorio Astronomico di Roma; and Brooke Simmons, of Oxford and
a former graduate student at Yale.
Story Source:
The above post is reprinted from
materials provided by
Yale University. The original item was written by Jim Shelton.
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