AMHERST, Mass. – Theoretical astronomer Neal Katz at the University of Massachusetts Amherst has received a Fulbright Scholarship to collaborate with colleagues in South Africa to study, teach and help guide observations on a new radio telescope by performing computer simulation models that will advance understanding of galaxy formation.
The Fulbright Scholar program, sponsored by the U.S. State Department’s Bureau of Educational and Cultural Affairs, was established in 1946 and emphasizes science diplomacy and international research collaborations between American researchers and their colleagues around the world. Over the past few years, Katz says, an average of two have been awarded each year in astronomy.
Beginning in September, Katz will embark upon a series of three visits lasting a few months each to work with colleagues at the University of Cape Town, the University of the Western Cape and the South African Astronomical Observatory to create computer simulations modeling galaxy formation. They will also build a large new array of radio telescopes to detect hydrogen in distant galaxies. The Fulbright award will pay for his travel and local support in Cape Town.
Katz is no stranger to southern Africa. In fact, several years ago he drove across the continent with a telescope, stopping in many villages to let people look through it at the stars. “During that trip I made a lot of connections that helped with planning this research,” he notes.
One of the more creative parts of his Fulbright study program will be for the first time incorporating some difficult-to-model processes in new, next-generation simulations of galaxy formation, Katz says. Galaxies are made of as many as 10 billion stars, but stars are a tiny fraction of a galaxy, the astronomer points out. Another big component that must be modeled is dark matter, something that is not ordinary or “baryonic” matter.
“By using computer simulations, we make a little model of the universe and we put in the physics we think is relevant,” he explains. “This can be very technically challenging. We need to simulate a large enough model so it is statistically significant but we also need to achieve small resolution. This limits our ability to include everything that might be relevant, but if you get to include all the relevant physical processes you wouldn’t need a model.”
Thus, he adds, one of the main difficulties in understanding galaxy formation today is which processes to include, and how to include them, in the simulations. “Once we have a simulation ready to go, it will take months to run on the world’s fastest supercomputers. Because they take so long we can’t do a lot of parameter exploration, that is, tweaking the variables. The better the simulation, the more reliable your results will be.”
Katz says the observational project, known as LADUMA, will be performed on a new radio telescope called MeerKAT. It is the precursor for an even large telescope, the Square Kilometer Array (SKA), which he believes is the biggest technical project ever attempted in Africa and will take many years to complete. Instead of one large dish, the telescope will be built as a linked array of many smaller dishes spread over several countries. When finished in 10 or 20 years it will have an effective dish size of almost one square kilometer.
“It’s a radio telescope that can detect hydrogen using a specific radio wavelength (21cm) to detect very distant galaxies,” Katz explains. “It’s very hard to detect individual galaxies so we will add images together from the different parts of the array. The trick of it is you have to add together the same types of galaxies, so the more you can refine the process the more precise you can be. That’s where simulations come in. You add galaxies together in different ways until you get what looks like a refined group. It offers a superior way of including the same types.”
Katz says, “By the time of my last visit, LADUMA data will be available and then we can actually use the simulations to figure out how to best analyze it.”
As part of its mission to “expand and strengthen relationships between people of the United States and citizens of other nations,” Fulbright Scholars are expected to give public talks, mentor students and engage with the host community in addition to their research and teaching.