A conversation with PRIYAMVADA NATARAJAN
I’m a theoretical astrophysicist, working on what I think are some of the most exciting, open and challenging questions. The first is trying to understand the nature of dark matter, and the second question pertains to the physics of black holes. Part of my interest in these two questions, aside from the fact that we now have an enormous amount of data that can help us understand these very enigmatic objects in the universe, is that we have a standard theory—a theoretical model—that works extremely well.
This is a model of structure formation in which dark matter, which is the dominant matter component in the universe, is in the driving seat. It’s the scaffolding in which all the first galaxies form, the first stars form, and so on. While we have this exquisite inventory and role for dark matter, we do not know what it is, what it’s composed of, what kind of particle it is, when it was created in the universe, and so on and so forth. Similarly, with black holes; we know that they exist. They are real. There is one in the center of our galaxy, which is a few million times the mass of the sun. The one in the center of our galaxy is a dormant black hole. It’s not doing very much at present, it was likely active in the past. We see in the early universe that there are massive black holes that are 1000 times, 10,000 times more massive than the one in the center of the galaxy that play a very important role in shaping the properties of the galaxy which hosts them.
What is the life-story of a black hole? How do they grow? How do they form, evolve, and then end up as dead black holes? This is an open question because we know that black holes feed on gas, but what we don’t understand is precisely how the gas makes it onto this peculiar surface that all black holes have called the “event horizon.” The physics, the astrophysics, if you will, or the details of the flow, are very poorly understood. Once again, these are both problems where we have a good, in fact, a rather specialized, detailed broad-brush understanding; however, the very nature of these objects remains unknown. The situation is very similar to that of dark matter that appears to be ubiquitous.
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