HILLSDALE, Mich., Oct. 17, 2017 /PRNewswire/ -- The Laser
Interferometer Gravitational-Wave Observatory (LIGO) Scientific
Collaboration and the Virgo Collaboration announced today that
gravitational wave detectors in the U.S. and Italy, as well as dozens of ground and space
observatories, have made the first detection of both gravitational
waves and light emanating from the collision of two neutron stars,
a detection termed "multi-messenger" astronomy. Ryan Lang, assistant professor of physics at
Hillsdale College, worked on this
historic achievement.
Gravitational Wave Research at Hillsdale
College
"Neutron stars are some of the most exotic objects in the
universe," said Lang. "By carefully studying the gravitational
waves from merging neutron stars like these, we can learn about the
fundamental structure of matter."
Lang has been working in the field of gravitational-wave science
for twelve years and with the LIGO project since August 2015, research that this year earned three
of the project's physicists a Nobel Prize. He is one of only three
professors from Michigan
institutions who are participating in the international
collaboration.
"This is an incredible day for the astrophysics world," said Dr.
Lang. "The detection of both gravitational waves and light from the
merger of these neutron stars has fulfilled the promise of LIGO and
Virgo as astronomical observatories. We have learned many new
things that we could not have determined with either piece on its
own. The era of multi-messenger astronomy has finally begun."
At Hillsdale College, Lang works
students to develop and use the computer codes which search LIGO
and Virgo data for gravitational waves, with a particular focus on
intermediate-mass black hole binaries. Lang also participates in
the LIGO Education and Public Outreach group, which develops and
disseminates resources to help the general public understand LIGO's
discoveries. He attended today's press conference as well.
Detection of GW170817
The observation, labeled GW170817, took place on August 17, and was made by the two Advanced LIGO
detectors in Louisiana and
Washington. The Advanced Virgo
detector in Italy also found a
small signal which, when combined with the information from the
LIGO detectors, allowed the source of the waves to be localized
more precisely than any gravitational waves detected previously.
Analysis of the waves revealed that two massive objects had
collided about 130 million light years from Earth. The masses of
the objects were determined to be about 1.1 to 1.6 times the mass
of the sun, much smaller than the masses of the four merging black
hole pairs previously observed by Advanced LIGO and Advanced Virgo.
These masses are consistent with neutron stars, the smallest and
densest stars known to exist. Neutron stars are only about 20
kilometers, or 12 miles, in diameter, but contain so much mass in
that small volume that a teaspoon of neutron star would weigh about
a billion tons on Earth.
Within seconds of the gravitational-wave detections, a
coinciding burst of gamma rays was observed by NASA's Fermi
Gamma-ray Space Telescope. Theorists have long suspected that
gamma-ray bursts like this one are caused by the mergers of neutron
stars. The simultaneous detection of GW170817 and a short gamma-ray
burst confirms this theory.
Theorists have also predicted that the initial "fireball" of
gamma rays should be followed by a mini supernova-like event called
a kilonova. With coordinates provided by the three-instrument
gravitational wave detection, optical telescopes were able to
search the sky and find this new point of light. About 70 space and
ground observatories ultimately observed the source emitting
different forms of light, or electromagnetic radiation: X-ray,
ultraviolet, optical, infrared, and radio. These observations have
shown that heavy elements, like gold and platinum, are created in
neutron star collisions and then spread throughout the universe,
again answering a long-standing question in astrophysics.
Press Conference and Publications
Representatives of the LIGO and Virgo collaborations discussed
GW170817 at a press conference in Washington, D.C. today. The scientists
explained the process and significance of the detection from both
the gravitational-wave and electromagnetic perspectives.
Physical Review Letters has published a paper detailing the
LIGO-Virgo detection, and additional papers from the collaborations
and their astronomical partners have been submitted to or accepted
by various journals.
Multimedia Resources
Photos of Dr. Lang are available here. Infographics, video
clips, and artists' renderings are available here.
About LIGO and Virgo Scientific Collaborations
LIGO is funded by the NSF, and operated
by Caltech and MIT, which conceived of LIGO and led
the Initial and Advanced LIGO projects. Financial support for
the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K.
(Science and Technology Facilities Council) and Australia (Australian Research Council) making
significant commitments and contributions to the project. More
than 1,200 scientists and some 100 institutions from
around the world participate in the effort through the LIGO
Scientific Collaboration, which includes the GEO Collaboration and
the Australian collaboration OzGrav. Additional partners are listed
at http://ligo.org/partners.php. The Virgo collaboration
consists of more than 280 physicists and engineers belonging to 20
different European research groups: six from Centre National
de la Recherche Scientifique (CNRS) in France; eight from the Istituto Nazionale
di Fisica Nucleare (INFN) in Italy; two in the
Netherlands with Nikhef; the MTA Wigner RCP in
Hungary; the POLGRAW group in
Poland; Spain with the University of Valencia; and the European Gravitational
Observatory, EGO, the laboratory hosting the Virgo detector
near Pisa in Italy, funded by CNRS, INFN, and Nikhef.
About Hillsdale College
Hillsdale College, founded in 1844,
has built a national reputation through its classical liberal arts
core curriculum and its principled refusal to accept federal or
state taxpayer subsidies, even indirectly in the form of student
grants or loans. It also conducts an outreach effort promoting
civil and religious liberty, including a free monthly speech
digest, Imprimis, with a circulation of more than 3.6
million. More information is available at hillsdale.edu.
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