Dr. John Ruan studies mergers of neutron stars (the leftover cores of dead massive stars) to understand the origin of the heaviest elements in the Universe. His research exploits a new window to the cosmos –ripples in space-time called gravitational waves. As Canada Research Chair in Multi-Messenger Astrophysics, Dr. Ruan studies neutron star mergers using both ‘cosmic messengers’ of light (as detected by telescopes) and gravitational waves (as detected by laser interferometers). Through these observations, he hopes to understand the nuclear astrophysics behind the cosmic alchemy of how heavy elements like gold were produced.
Traditionally, astronomical observations are performed using telescopes, which detects light from distant objects like stars and galaxies for study. However, over a century ago, Einstein’s theory of general relativity predicted the existence of another cosmic messenger: gravitational waves. These ripples in space time should be generated during the mergers of dense objects such as black holes and neutron stars in distant galaxies. The resulting gravitational waves could then be detected as they passed by the Earth as the transient stretching and compression of space itself.
Gravitational waves were first detected in 2015 by the Laser Interferometer Gravitational Wave Observatory, from a merger of two black holes. Although this breakthrough discovery led to the award of the 2017 Nobel Prize in Physics, no light from this merger was detected, because black holes do not have a surface. However, gravitational waves from the merger of two neutron stars were detected in 2017, which emitted light that was detected by telescopes around the world (including the Chandra X-ray Observatory in work led by Dr. Ruan). The light emitted was in part due to the production of heavy elements produced in the neutron star material ejected during the merger.
It is currently unclear whether neutron star mergers are responsible for the production of all the heaviest elements in the Universe. To answer this question, Dr. Ruan’s research group is working on innovative approaches at the intersection of nuclear astrophysics, statistic, and machine learning, to infer how much of each heavy element is produced in each merger. Over the next decade, many more neutron star mergers will be detected, and Dr. Ruan will use telescopes to observe them with the ultimate goal of conducting a cosmic census of the heaviest elements.
Through support from his Canada Research Chair, Dr. Ruan is able to support his undergraduate and graduate students in research, thus training them to innovative and make the next landmark discoveries. Thanks to the research funding that comes with the position, he hires a team of students to conduct research in his newly-renovated research lab at Bishop’s. The small size of the university and low student-to-faculty ratio at Bishop’s increases opportunities for students to join in cutting-edge research, whether it be about the cosmic origin of the elements or searching for planets around other stars. In addition to the research itself, the close connections and mentorship built through these experiences often play a decisive role in helping students at Bishop’s to advance to graduate school and pursue a PhD.
Dr. Ruan praises the Office of Research and Graduate Studies at Bishop’s for their integral support for faculty seeking grants. In addition to providing administrative help for faculty like him when they apply for government research grants, they also help undergraduate students apply for scholarships and experiential learning opportunities.