This blog consists of daily news items of interest to followers of QUIDDITY as a qualitatitive method of describing the world. This approach was described by Clive Barker in "The Great and Secret Show" and analyzed in the 149 posts of the QUIDDITY blog of this writer (see link to companion blog).
Wednesday, June 28, 2017
Binary Black Holes Studied
Astronomers Detect Orbital Motion in Pair of Supermassive Black Holes VLBA reveals
first-ever black-hole "visual binary"
Using the supersharp radio
“vision” of the National Science Foundation’s Very Long Baseline Array (VLBA),
astronomers have made the first detection of orbital motion in a pair of upermassive
black holes in a galaxy some 750 million light-years from Earth.
The two black holes, with a
combined mass 15 billion times that of the Sun, are likely separated by only
about 24 light-years, extremely close for such a system.
“This is the first pair of black
holes to be seen as separate objects that are moving with respect to each
other, and thus makes this the first black-hole ‘visual binary,'” said Greg
Taylor, of the University of New Mexico (UNM).
Supermassive black holes, with
millions or billions of times the mass of the Sun, reside at the cores of most
galaxies. The presence of two such monsters at the center of a single galaxy
means that the galaxy merged with another some time in the past. In such cases,
the two black holes themselves may eventually merge in an event that would
produce gravitational waves that ripple across the universe.
“We believe that the two
supermassive black holes in this galaxy will merge,” said Karishma Bansal, a graduate
student at UNM, adding that the merger will come at least millions of years in
The galaxy, an elliptical galaxy
called 0402+379, after its location in the sky, was first observed in 1995. It
was studied in 2003 and 2005 with the VLBA. Based on finding two cores in the
galaxy, instead of one, Taylor and his collaborators concluded in 2006 that it
contained a pair of supermassive black holes.
The latest research, which
Taylor and his colleagues are reporting in the Astrophysical Journal,
incorporates new VLBA observations from 2009 and 2015, along with re-analysis
of the earlier VLBA data. This work revealed motion of the two cores,
confirming that the two black holes are orbiting each other. The scientists’
initial calculations indicate that they complete a single orbit in about 30,000
“We need to continue observing
this galaxy to improve our understanding of the orbit, and of the masses of the
black holes,” Taylor
said. “This pair of black holes offers us our first chance to study how such
systems interact,” he added.
The astronomers also hope to
discover other such systems. The galaxy mergers that bring two supermassive
black holes close together are considered to be a common process in the
universe, so astronomers expect that such binary pairs should be common.
“Now that we’ve been able to
measure orbital motion in one such pair, we’re encouraged to seek other,
similar pairs. We may find others that are easier to study,” Bansal said.
The VLBA, part of the Long
Baseline Observatory, is a continent-wide radio telescope system using ten,
240-ton dish antennas distributed from Hawaii
to St. Croix in the Caribbean. All ten
antennas work together as a single telescope with the greatest resolving power
available to astronomy. That extraordinary resolving power allows scientists to
make extremely fine measurements of objects and motions in the sky, such as
those done for the research on 0402+379.