Network of pulsars being used to search for gravitational waves — Gravitational waves, or ripples in spacetime predicted by general relativity, cause changes in the arrival times of pulsar radio signals that are correlated between pulsars in a way that depends on their angular separations. They are detectable from Earth with sensitive radio timing observations.Figure by David Champion, Max Planck Institute for Radio Astronomy, Bonn, GermanyMaura McLaughlin, Eberly distinguished professor of physics and astronomy at West Virginia University, will serve as co-director; Xavier Siemens, a physicist at the University of Wisconsin-Milwaukee, is the principal investigator and was named director of the center.

“PFCs are awarded to teams working to address the most significant questions regarding the fundamental nature of our universe and the underlying physics,” said Fred King, WVU vice president for research. “The universities in this collaboration join a very select group of institutions who work at the forefront of physics and astronomy.”

“This award recognizes the unique expertise WVU faculty and students bring to exploring one of the most challenging questions in modern astrophysics.”

Maura McLaughlinWest Virginia UniversityThe NSF currently supports 10 other PFCs, which range in research areas from theoretical biological physics and the physics of living cells to quantum information and nuclear astrophysics at institutions such as the Massachusetts Institute of Technology, Harvard University, the California Institute of Technology, the University of Wisconsin, the University of Notre Dame, the University of Chicago, the University of California at Santa Barbara, the University of California at San Diego, the University of Colorado and the University of Maryland.

The NANOGrav PFC will also provide funding for 23 senior personnel, six postdoctoral researchers, 10 graduate students and 25 undergraduate students distributed across 11 institutions.

At WVU, McLaughlin; Duncan Lorimer, professor of physics and astronomy; and Sean McWilliams, assistant professor of physics and astronomy, are members of NANOGrav and will contribute to NANOGrav PFC activities.

Universe of mystery

The NANOGrav PFC will address a transformational challenge in astrophysics – the detection of low-frequency gravitational waves.

“This center will ensure that researchers have the resources necessary to explore one of the most exciting frontiers in all of physics and astronomy,” said Siemens.

Theories suggest that gravitational waves, which are ripples in the fabric of space-time, should arise from extremely energetic and large-scale cosmic events such as orbiting pairs of massive black holes found at the centers of merging galaxies or the period just after the Big Bang when all of the universe that we can see expanded rapidly from a minuscule volume in a tiny fraction of a second.

In Einstein’s theory of gravity, general relativity, these events produce waves that distort, or ripple, the actual fabric of the cosmos as they emanate throughout space. So far, the waves have proved elusive, but the search for them is intensifying.

For the signals that NANOGrav is searching for, the wavelengths are so long – significantly larger than our solar system – that it would be impossible to build a detector large enough to observe them. Fortunately, the universe created its own detection tool – millisecond pulsars.

Pulsars are rapidly spinning, superdense remains of massive stars that have exploded in supernovae. These ultra-stable stars are nature’s most precise celestial clocks, appearing to “tick” every time their beamed emissions sweep past the Earth like a lighthouse beacon.

Gravitational waves may be detected in the small but perceptible fluctuations – a few tens of nanoseconds over five or more years – that they cause in the measured arrival times at Earth of radio pulses from these millisecond pulsars.

“The detection of gravitational waves will be a watershed moment in the history of science,” said McWilliams. “Beyond being the strongest evidence available in support of general relativity as the correct theory of gravity, the signals that NANOGrav will detect will provide us with information about the evolution of galaxies and supermassive black holes over most of cosmic history. This information is impossible to acquire through conventional electromagnetic observations.”

About the project

Green Bank Telescope.West Virginia UniversityNANOGrav research makes use of the unique capabilities of the largest, fully steerable single-dish radio telescope in the world, the Green Bank Telescope at the National Radio Astronomy Observatory in Pocahontas County, as well as the Arecibo Observatory in Puerto Rico. The GBT is located in the National Radio Quiet Zone, which protects the incredibly sensitive telescope from unwanted radio interference, enabling it to study pulsars and other astronomical objects.

“NANOGrav is fortunate to have access to the two most sensitive radio telescopes in the world for this groundbreaking research”, McLaughlin stated. “Furthermore, as many of our observations are performed by students, the telescopes are serving a vital role in creating a pipeline for science and technology fields.”

Because of the importance of the GBT for NANOGrav science, the NANOGrav PFC will contribute $500,000 a year to support telescope operations. WVU researchers have been observing the sky from its enormous dish since 2006 and established a partnership the GBT in 2013.

“The GBT is currently being used to survey the low-frequency radio sky for millisecond pulsars,” said Lorimer. “The pulsars that are being found are providing significant improvements to NANOGrav’s sensitivity to gravitational waves. The GBT is really a critical part of NANOGrav and thePFC over the next decade.”

The research performed by the PFC is distributed among the participating institutions and members of NANOGrav.

In addition to the three faculty members at WVU, other personnel funded by the NANOGrav PFC include researchers from the California Institute of Technology, Cornell University, Franklin and Marshall College, Lafayette College, Montana State University, Universities Space Research Association and NASA’s Goddard Flight Center, the National Radio Astronomy Observatory, Oberlin College, the University of Texas at Brownsville, and the University of Wisconsin-Milwaukee.

They will collaborate closely with the University of British Columbia in Vancouver and McGill University in Montreal.

“The combination of knowledge, talents and resources in the NANOGravPFC will bring scientists even closer to discoveries that could transform what we know about our universe and how it was created,” said Earl Scime,vice president for research and distinguished professor of physics and astronomy. “WVU’s significant role in this program speaks to the high caliber of our physics and astronomy faculty and research.”

NANOGrav was founded in 2007 and at the time consisted of 17 members in the United States and Canada. It has since grown to 55 scientists and students at 15 institutions.

By bringing together astronomers and physicists from across the U.S. and Canada to search for the telltale signature of gravitational waves buried in the incredibly steady ticking of distant pulsars, NANOGrav is advancing thePFC mission to foster research at the intellectual frontiers of physics and to enable transformational advances in the most promising research areas. More information can be found at http://nanograv.org.