The 'galactic ecosystem' at the Milky Way's center

Fulbright-funded collaboration sends astronomer to Chile

The 'galactic ecosystem' at the Milky Way's center
August 1, 2018

Daniel Wangastronomy, has received a Fulbright Scholar award to make what he calls “an astronomical pilgrimage,” to Chile, the “world capital of ground-based astronomical observation and home to more than half of the world’s largest radio and optical telescopes. He plans to collaborate with colleagues there to study the massive black hole and its environment at the center of the Milky Way.  

“I am an observational astronomer, and my collaborator at the Institute of Astrophysics at Pontificia Universidad Catolicaprofessor Jorge Cuadra, is a theorist,” Wang explains. “We want to complement each other to reach a better understanding of black hole accretion and how our galaxy’s outflow interacts with the galactic center environmentto see better how this system works. Another goal is to develop a stronger, wider collaboration with the Chilean astronomy community.” 

The Fulbright award will pay for his travel and local support in Chile for the semester from August to December. Wang’s visit will also be supported by Cuadra’s university, after their proposed collaboration was selected in a competition for programs that will strengthen the international academic networkAs the host country, Chile provides its astronomers about a 10 percent share of observing time on its telescopes, Wang says, offering a generous and valuable opportunity. 

“They have a unique observing opportunity in the Atacama Desert of northern Chileits the best in the world,” he says. There are five astronomical institutes in Santiago alone. He adds, I’ll have a chance to visit a few of these observatories and institutes, for an unusual extended visit. Usually people go for an observation and then leave, but the Fulbright offers special opportunities for longer research collaboration, mentoring and teaching, guest lecturing, a departmental colloquium and public talks. It potentially means more opportunities for my students in the future, too.” 

Wang says, “Cuadra is a leading expert on computer simulations, I am primarily an observer. We share a common research interest in the galactic center. One goal of my visit to Chile is to establish a strong, long-term collaboration on high-energy astrophysics education and research and, in particular, on a comprehensive observational and theoretical study of the heart of our galaxy.” 

The galaxy’s center is “full of interesting astronomical objects and phenomena,” including the closest known massive black hole, known as Sgr A*, Wang explains. It is surrounded by a population of young massive stars with strong, fast winds and a cusp of old stars accumulated over the history of the galaxy, and by a ring of cold gas, all within a radius no more than a few times the average distance between stars in the galaxy, and all of these strongly interact with each other. 

Wang, with a long-standing research interest in the galactic center, led the first large-scale surveys of the region with the Chandra X-ray Observatory and the Hubble Space Telescope and more recently with the Large Millimeter Telescope, a joint facility of Mexican institutions with UMass Amherst. The research on Sgr A* started about four years ago during his visit to the Institute of Astronomy at Cambridge University, where he began the collaboration with Cuadra 

“We were both members of an international team working on the 3-megasecond Chandra observation of the ‘X-ray visionary project’ on Sgr A*,” he notes. “Now some of the big questions we’ll be asking is how this black hole interacts with the galactic ecosystem, whether these interactions have cycles, how the black hole affects star formation and how much the central region affects the entire galaxy.” 

Over the past five years, Wang says that their work has demonstrated that joint theoretical and observational studies can effectively provide insights into the working of various complicated physical processes in the center of the galaxy. He says, “I envision that the results of our work will be of broad interest to both the galactic center research community and to those trying to understand the intimate relationships of galactic nuclei with various galaxy-wide properties.  

At UMass, he has developed and taught classes including extragalactic astronomy, stellar astrophysics and high-energy astrophysics at the graduate level, and has mentored many undergraduate and graduate students and postdoctoral fellows. 

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.