Exploring the Universe
Every so often, one galaxy collides with another. In any billion years, about 10 percent of fairly bright galaxies are involved in mergers of, well, cosmic proportions. For example, for hundreds of millions of years, our own Milky Way Galaxy has been nibbling at the smaller Sagittarius Dwarf Elliptical Galaxy, which intersects the plane of the Milky Way at an angle.
Vivienne Baldassare (Macaulay Honors College at Hunter College, 2012) wonders whether there’s a relationship between collisions and the detection of X-rays, which spew from the super-massive black hole that’s at the nucleus of every galaxy.
Armed with a 2012 National Science Foundation Graduate Research Fellowship, she’s about to start doctoral work at the University of Michigan-Ann Arbor, looking at mergers in ultra-luminous infrared galaxies – that is, in galaxies with an “active” nucleus that emits 1012 times the infrared light that our sun does.
The NSF Graduate Research Fellowships are the most prestigious awards a graduate student in the STEM disciplines (science, technology, engineering and mathematics) can receive. Providing $126,000 over three years, they recognize and support exceptional students who have proposed graduate-level research projects in their fields.
“I hope that my research will contribute to our understanding of the role that galaxy mergers and active galactic nuclei play in galaxy evolution,” she says.
Her research question arises from the fact that instruments detect X-rays from some galactic nuclei but not others. “One possible explanation is there may be dust blocking the X-rays in the active galaxies for which we don’t see them,” she says. [Active galaxies have active nuclei, which generate above-average emissions across a broad array of wavelengths.] “In galaxy mergers, a lot of gas and dust come together from the individual galaxies, so it would make sense that their active galactic nuclei are obscured. I’d like to see if galaxies in earlier stages of merger are not detected in X-ray, while galaxies in later stages of mergers are.”
A good question, but the merger of two galaxies can span 3 billion years. “In our timescale, I wouldn’t expect to see any changes, so I’ll need a large sample of galaxies at different merger stages,” she says. “Some large astronomical surveys have data for millions of galaxies, so ideally one could use data from these surveys to test predictions like this.”
Baldassare knew she’d major in physics when she enrolled at Hunter, but she didn’t find her niche until she landed a summer internship after her freshman year through Macaulay Honors College. Associate Professor Charles Liu at the College of Staten Island, who also works in the Department of Astrophysics at the American Museum of Natural History, asked her to classify galaxies according to their shapes. “I’d never thought about astronomy as a career, but I found I loved it,” she says.
She stayed with him a semester longer, leading into a series of projects focused on some of the diverse mysteries of the cosmos.
She worked with her mentor, Kelle Cruz, an assistant professor of physics and astronomy at Hunter and a research associate in the Department of Astrophysics at the American Museum of Natural History, to study the age and evolution of brown dwarfs. These are wannabe stars – bigger than gas giant planets, smaller than stars and lacking an energy source at their core. This project was funded by a grant from the John P. McNulty Scholarship Fund for Excellence in Math and Science.
In the summer of 2011, Baldassare moved on to the National Optical Astronomy Observatory under a Research Experience for Undergraduates grant funded by the National Science Foundation.
“We were studying a set of ultra-luminous infrared galaxies, which get their extreme luminosities from active galactic nuclei and/or bursts of star formation,” she says. “We had a sample of objects and were testing to see which of those scenarios was playing out.”
Baldassare also started a blog, Physicist/Feminist (http://physicistfeminist.wordpress.com/author/vbaldassare/), “because I feel strongly about increasing the representation of women in the sciences. In some sciences, like psychology and biology, the numbers are close to even, but in physics, engineering and math, women are underrepresented.”
On her blog and a Twitter feed, she “has gotten good feedback from other women scientists.”
A recent blog post recounted a talk at the CUNY Graduate Center by Jill Tarter, the director of the Center for Search for Extraterrestrial Intelligence. Not only did Tarter discuss the more than 2,000 distant planets detected so far, some of which may harbor life, but also she “had some great advice (which is relevant for all scientists).” To be:
“Positive. Others can and will try to discourage you. Remain positive and don’t let it affect you.
“Realistic. Try to find metrics to measure your own performance. How are you doing in relation to your peers? Figure out what do you need to be able to do the things you want.
“Flexible. You probably won’t end your career doing what you started, so be flexible. Figure out what problem-solving skills you have and then figure out what the most interesting problems are. Be willing to use your skill sets to solve these problems.
Kind. Be kind to yourself! And especially be kind to other women. Support other female scientists.
“These are qualities I will definitely try to maintain throughout my career!” Baldassare wrote.
For all her current and prospective exploration of the universe, there is one thing on her wish list that she knows she will never accomplish. “In an estimated five billion years, the Milky Way will merge with Andromeda, the closest large galaxy to us,” Baldassare says. “It probably will be very beautiful, and I’m sorry I won’t be here to see that.”