READING, Pa. — Ruth A. Daly, professor of physics at Penn State Berks, will conduct research at the Flatiron Institute, which is funded by the Simons Foundation. This support will help underwrite Daly's year-long, 2019-2020 sabbatical to expand her theoretical astrophysics and cosmology research of the universe and objects in the universe, with an emphasis on black holes and the acceleration of the universe.
A member of the college’s faculty since 1999, teaching physics and astronomy, Daly conducts research focused on the properties of black holes, the formation and evolution of structure in the universe, and the evolution of the universe itself, such as the expansion and acceleration histories of the universe.
The mission of the private Simons Foundation in New York City is to advance the frontiers of research in mathematics and the basic sciences, including physics. The foundation exists to support basic or discovery-driven scientific research undertaken in the pursuit of understanding the phenomena of our world.
The foundation’s Flatiron Institute, also in New York City, advances scientific research in astrophysics, biology and quantum physics through computational methods, including data analysis, modeling and simulation.
An exciting time for her fields
Daly stated that this is an exciting time for the fields of astrophysics and cosmology as we try to find our place in the universe, and these fields are alive and well at Penn State Berks.
“What do we mean by ‘astrophysics’ and ‘cosmology,’ and how do they impact the community and the world? Astrophysics involves the application of physics to astronomical objects, such as galaxies, black holes, stars, planets, and everything else that is in the universe,” she explained, adding that cosmology is the study of the properties and history of the universe itself.
Daly said she is currently concentrating on the acceleration of the universe and the properties of supermassive black holes, astrophysical objects that are currently the focus of many studies, including those at Penn State Berks.
“You may think of a black hole as an object that does not emit any light –- so how can a black hole be studied?," said Daly. "As stars and gas get close to a black hole, stars begin to orbit the black hole very rapidly and gas is heated to very high temperature. If we find stars orbiting a region very rapidly but we don’t see emission from anything inside the stellar orbits, then we can conclude that there must be a black hole there, and the mass of the black hole can be estimated."
She added that we can draw an analogy with the solar system.
“By studying the motion of the planets in the solar system, we can determine the mass of the sun, since the gravitational field of the sun is holding the planets in their orbits," said Daily. "Imagine if we saw a system with similar orbits, but with no visible sun at the orbital center – then we would conclude the planets are orbiting a black hole.”
Gases also found near black holes
Daly noted that gas can also find itself near a black hole; in this case, one can see very hot, X-ray-emitting gas orbiting a region with nothing visible inside the ring or disk of hot gas.
Sometimes, very powerful jets of material are flung from the area close to a black hole, and these can be studied with radio telescopes and interferometers, such as the National Radio Astronomy Observatory Very Large Array (VLA) in New Mexico and the Giant Metrewave Radio Telescope (GMRT) in India.
Daly said she and her collaborators have been fortunate to be awarded significant observing time at the VLA and the GMRT.
Exploring ages of the universe
Daly uses data gathered from extragalactic radio sources to understand the properties of black holes, such as their rate of spin, as well as to study the global geometry and expansion history of the universe.
The strong radio sources, she explained, can be used to study the global geometry and history of the universe, in addition to helping us to understand the properties of black holes.
“Since different sources are located at different distances, we can study the universe as it was at a variety of ages, all the way from a few billion years to its current age of about 14 billion years. The properties and structure of the universe at different ages allow us to piece together the history of the universe,” she said.
She frequently includes students on research projects, many of which result in publications with students as co-authors. Her research findings also have received numerous citations from scientific colleagues.
Students involved with research projects at Penn State Berks develop valuable transferable skills, said Daily, such as the ability to collaborate and work with others, to search and test for systematic and other types of errors, and to describe and explain their results. Students also gain familiarity with a variety of computer environments and software packages.
In addition to determining and announcing in 1998 that the universe's expansion is accelerating, Daly developed a method of studying the expansion and acceleration of the universe that does not require that a theory of gravity or contents of the universe be specified. The method only requires that a space-time metric be specified.
Latest discovery advances the field
Most recently, Daly discovered a tenfold increase (from 100 to 1000) in the number of sources for which magnetic field strengths and black hole spins could be determined. She will present those findings at a conference at the Aspen Center for Physics in Colorado in March 2019.
“It is fascinating to think about the universe, and rewarding for me to have an impact with my research,” she said.
In terms of important problems today, “finding a signal of life on another planet would be huge, as would be determining what constitute the dark energy and dark matter that make up about 95 percent of the universe," said Daly. "Only about five percent is normal matter (atoms, electrons, neutrons, etc.) that we can see."
Daly, a native of New York City, earned a doctorate and master of arts in astronomy and physics from Boston University, and bachelor of arts in psychology and English from Boston College. She has held the titles of associate and assistant professor at Penn State Berks; visiting assistant professor at Bucknell University; assistant professor, instructor and research associate at Princeton University; and postdoctoral fellow at the Institute of Astronomy, Cambridge, England.
Her awards include Penn State Berks Outstanding Researcher (2006), NSF National Young Investigator (1993-2002), NATO-NSF Postdoctoral Fellow (1987-1988) and NASA Graduate Student Research Fellowship (1986-1987).
For more information about Daly and her research, visit sites.psu.edu/rdaly.