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Post-doctorate publishes paper on dark matter

| Thursday, December 11, 2014

Notre Dame post-doctoral fellow Joseph Bramante co-authored a paper entitled “Detecting Dark Matter with Imploding Pulsars in the Galactic Center” with University of Chicago astrophysicist Tim Lindon that explores how detecting imploding pulsars may lead provide insights about the properties of dark matter.

Bramante said studies high-energy theory, a field which includes the study of particle physics, high energy processes and reactions of the universe at the smallest distances.

“I do research in a few different areas, including cosmological inflation, dark matter and high energy phenomenology,” Bramante said. “I was looking at possible consequences of a specific kind of dark matter called asymmetric dark matter and what it could possibly do to pulsars at the galactic center.”

Physical Review Letters, a website self-described as “the world’s premier physics letter journal,” published Bramante’s paper Nov. 3.

“It’s really not so hard to understand,” Bramante said. “Most of what we’re made of is matter, and not anti-matter. One way to think about it is if our universe started off as just very very dense energy, which we think it did, there’s a symmetry between matter and anti-matter that seems to indicate that it should’ve produced equal parts matter and anti-matter, but we don’t see that, we see mostly just matter.

There’s a completely separate question — which is, what makes up all this dark matter that we see in galaxies? We know there’s dark matter, and we know that there’s about five times more dark matter than there is normal matter. […] we don’t really know anything about it, how heavy it is, whether it is just a particle or an extended object, that’s the focus of the ​research. And so getting knowledge of any of its properties, since it’s never been detected​ directly​,​ ​is one of the major questions right now in particle physics.”

Bramante said the text explores the lack of pulsars in the galactic center and what that void is a result of and will cause in the future.

“I was able to show in writing the paper that recently they haven’t been seeing pulsars in the galactic center, and if there’s asymmetric dark matter with a certain scattering off of ​normal matter ​and ​with certain self-interactions, then it could make pulsars in the galactic center collapse into black holes and essentially leave pulsars outside of the galactic center alone,” Bramante said.

If the particular kind of dark matter Bramante discusses does indeed exist in a particular range of parameter space, then his paper has potentially huge implications, he said.

“Dark matter is important because we’re at a juncture with particle physics and energy theory in general where the standard model is complete,” Bramante said, “​But w​e know that there has to be something​ additional​ that accounts for dark matter. So in that sense finding dark matter isn’t just interesting because you find a new particle, but you gain some indication about what other symmetries govern nature, because in the end when people say the standard model of particle physics or what that is, it’s really a set of symmetries that govern how particles interact.

“The reason we look for new particles is because we’re interested in what the underlying symmetries of nature are.”

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About Andrea Vale

Andrea Vale is a freshman at Notre Dame who has previously written for both the Sun Chronicle and the Huffington Post. She plans to major in English with a Creative Writing concentration and a minor in Journalism.

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