Prof. Joe Romano, UT Rio Grande Valley

"The Hellings and Downs correlation curve: What it is and why it plays such an important role for pulsar timing array searches for gravitational waves"

Abstract: By precisely monitoring the "ticks" of Nature's most precise "clocks" (pulsars), astronomers have recently reported evidence for a background "hum" of low-frequency gravitational waves (GWs). A possible source for this observed signal is the combination of GWs produced by hundreds of thousands of pairs of super-massive black holes orbiting one another in the centers of merging galaxies. In this talk, I will describe these observations, paying specific attention to the Hellings and Downs correlation curve --- the "smoking gun" signature that the signal was of GW origin. For reference, I will make comparisons to the more familiar detections of GWs made by the LIGO and Virgo detectors over the past 8 years.

Bio: Joe Romano is currently a Professor of Physics at UT Rio Grande Valley. His primary research interest is gravitational-wave (GW) data analysis, focusing on searches for stochastic GW backgrounds (the GW analogue of the electromagnetic cosmic microwave background). He has helped develop search methods for GW backgrounds using data from ground-based detectors like LIGO and Virgo, space-based detectors like the planned mission LISA, and pulsar timing arrays. Many, many years ago, he did research in the field of quantum gravity.