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Nepal-Born Researcher Sudarshan Karki Part of Scientific Breakthrough

LIGO Opens New Window on the Universe with Observation of Gravitational Waves from Colliding Black Holes. For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.

The gravitational waves were detected on Sept. 14, 2015, at 5:51 a.m. Eastern Daylight Time (9:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

The LIGO group at UO has played a crucial role in the GW150914 discovery, both in developing key instrumentation at the LIGO observatories and in confirming GW150914 as being pure of astrophysical origin. The UO group is responsible for the LIGO “environmental monitoring” system — a suite of instruments which determine the terrestrial conditions at the observatories: weather conditions, ground motion, radio, and magnetic interferences, cosmic ray events, acoustic disturbances, etc. Robert Schofield, a research professor at UO, was able to demonstrate that such terrestrial influences had a completely negligible effect on the GW150914 signal.

Other members of the UO group also played key roles in developing the environmental instrumentation and interpreting the data pertinent to GW150914. They consist of postdoctoral researcher Dipongkar Talukder, graduate students Sudarshan Karki, Ryan Quitzow-James, Jordan Palamos, Vinny Roma, and Paul Schale, and faculty members Raymond Frey and James Brau.

Sudarshan Karki, a Nepal-born Graduate Research Assistant at the University of Oregon is part of the team who made the breakthrough.  Karki, Palamos, and Roma were all present at the LIGO Hanford Observatory (LHO) at the time of GW150914. Karki had spent the previous year at LHO developing a novel system for calibrating the minute displacements (0.01% the diameter of a proton) of the LIGO mirrors due to the passage of gravitational waves.

The UO contingent was one of the founding groups of the LIGO Scientific Collaboration, which was formed in 1997. The UO group was initially led by Prof. James Brau, and more recently by Prof. Raymond Frey. Dr. Schofield has been in the UO LIGO group since 1998. The group’s research has been supported by the National Science Foundation.

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LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1000 scientists from universities around the United States and in 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data; approximately 250 students are strong contributing members of the collaboration.

The LSC detector network includes the LIGO interferometers and the GEO600 detector. The GEO team includes scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI), Leibniz Universität Hannover, along with partners at the University of Glasgow, Cardiff University, the University of Birmingham, other universities in the United Kingdom, and the University of the Balearic Islands in Spain.

LIGO was originally proposed as a means of detecting these gravitational waves in the 1980s by Rainer Weiss, professor of physics, emeritus, from MIT; Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus; and Ronald Drever, professor of physics, emeritus, also from Caltech.

Virgo research is carried out by the Virgo Collaboration, consisting of more than  250 physicists and engineers belonging to 19 different European research groups: 6 from Centre National de la Recherche Scientifique (CNRS) in France; 8 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; 2 in The Netherlands with Nikhef; the Wigner RCP in Hungary; the POLGRAW group in Poland and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy.

The discovery was made possible by the enhanced capabilities of Advanced LIGO, a major upgrade that increases the sensitivity of the instruments compared to the first generation LIGO detectors, enabling a large increase in the volume of the universe probed—and the discovery of gravitational waves during its first observation run. The US National Science Foundation leads in financial support for Advanced LIGO. Funding organizations in Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council, STFC) and Australia (Australian Research Council) also have made significant commitments to the project.

Several of the key technologies that made Advanced LIGO so much more sensitive have been developed and tested by the German UK GEO collaboration. Significant computer resources have been contributed by the AEI Hannover Atlas Cluster, the LIGO Laboratory, Syracuse University, and the University of Wisconsin-Milwaukee.  Several universities designed, built, and tested key components for Advanced LIGO: The Australian National University, the University of Adelaide, the University of Florida, Stanford University, Columbia University of New York, and Louisiana State University.

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