UWM Leads Search for Quintessential Information About Universe

Newswise — MILWAUKEE – The University of Wisconsin-Milwaukee and partners at 10 other U.S. research institutions have landed a highly competitive $14.5 million grant from the National Science Foundation (NSF) to advance efforts to detect low-frequency gravitational waves in the universe.

Gravitational waves are elusive ripples in the fabric of space and time, which Albert Einstein predicted should arise from extremely energetic cosmic events. Low-frequency waves carry the imprint from supermassive black hole mergers and events from the period just after the Big Bang when scientists theorize that the entire universe expanded in size from sub-microscopic to gargantuan in an instant.

The funding brings together astronomers and physicists from the research consortium called NANOGrav, to form a Physics Frontiers Center, directed by Xavier Siemens, a UWM associate professor of physics. The center will search for the telltale “signatures” of gravitational waves using a unique method to measure the signals from pulsars.

Siemens recently answered some basic questions about the quest for gravitational waves.

Before we talk about pulsars, tell us a little more about gravitational waves. Why is it so important to find physical evidence of them?We’re talking about gravitational waves with very low frequencies – waves with wavelengths much longer than the size of our Solar System. These waves are produced by the coalescence of supermassive twin black holes that form when galaxies merge, and also by sources in the very early universe. So these waves can tell us about how the very early universe formed.

With such huge waves lengths, how can scientists possibly hope to find these gravitational waves?Fortunately, nature itself has provided us with its own detection tool – millisecond pulsars.

What are pulsars?They are rapidly spinning, super-dense remains of massive stars that have exploded. And they are nature’s most precise celestial clocks. They send out beams of radio waves from their magnetic poles as they spin, like beams from a lighthouse. These sweep past the Earth at extremely regular intervals and appear to us as pulsating radio stars.

So then how do pulsars reveal the presence of gravitational waves?As gravitational waves pass through the galaxy, they change the arrival times of pulses on Earth. Gravitational waves cause small but detectable fluctuations in the measured arrival times of the radio pulses — and by small, I mean a few tens of nanoseconds!

What tools are available to monitor the pulsars?This research makes use of the two most sensitive telescopes in the world – the Arecibo Observatory in Puerto Rico and the National Radio Astronomy Observatory’s Green Bank Telescope in West Virginia. Arecibo is the largest single dish radio telescope in the world. Having the two most sensitive radio telescopes at our disposal means we have access to the best data to do our work.

What is NANOGrav and when did UWM join its ranks?NANOGrav is the North American Nanohertz Observatory for Gravitational Waves, a collaboration that aims to study the universe using gravitational waves. It was founded in 2007, and UWM joined its ranks in 2008.

Recently I was voted in as chair of the NANOGrav collaboration. Being able to start as a member in 2008 to becoming chair of the group in 2015 is a result of UWM’s support of our research group. I’ve been able to invest the time to become knowledgeable in this area. This support has now paid off with UWM leading this center.

This center, led by UWM, is one of 10 such centers nationally. What is the significance of being named a Physics Frontier Center?These are very high-impact, high-visibility centers. Among the directors of the 10 current PFCs are three Nobel Prize winners. That sets the bar for us.

http://www5.uwm.edu/news/2015/03/30/new-nsf-funded-physics-frontiers-center-joins-the-race-to-detect-gravitational-waves/#.VRl7JLqUebI

Other institutions on the grant: California Institute of Technology, Cornell University, Franklin and Marshall College, Lafayette College, Montana State University, Universities Space Research Association and NASA’s Goddard Space Flight Center, National Radio Astronomy Observatory, Oberlin College, University of Texas at Brownsville, and West Virginia University.