Friday, September 23, 2016

Meet the Visitor: Justin Finke, from the Naval Research Labs

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The first guest speaker for Seminar this year was Justin Finke, a physicist at the Naval Research Labs, who gave his talk entitled ‘Gravitational Waves from Merging Black Holes and the Connection to Black Holes in Ultraluminous X-Ray Sources.’

Dr. Finke visited us on the day after the first anniversary of the discovery of gravitational waves (an article about this anniversary can be found on LIGO’s website here).  On September 14, 2015, gravitational waves were first detected with the merging of two of black holes. This event happened exactly as general relativity had predicted and additionally lead to the realization that black holes greater than 10 solar masses exist.

Gravitational waves are waves produced by an extremely accelerated mass. Usually these masses are orbiting black holes or neutron stars. Throughout his talk, Dr. Finke mentioned how pulsars (a neutron star that rotates at extremely high speeds) helped to show the existence of gravitational waves, before gravitational waves were observed.  Pulsars can be used because they emit pulses at an extremely regular rate, allowing them to act as a “clock.”

In order to thoroughly investigate gravitational waves, it is important to find the merger rate of Binary Black Holes (BBH). Dr. Finke explained that his work involved inferring the BBH merger rate by looking at the formation of Ultraluminous X-ray sources (ULXs). A ULX is an object which exceeds the Eddington limit, which is supposed to be the maximum brightness that an object in space can have. To some degree this limit is related to metallicity, which for astronomers, means the fraction elements heavier than H or He. The less metallicity a celestial object has, the greater the brightness.

In the future, Dr. Finke and his team hope to find the relationship that links ULXs and metallicity.

After Justin Finke finished his seminar on gravitational waves, we approached him for an interview. Dr. Finke was kind enough to answer the following questions we had for him.

Was your work on gravitational waves done in collaboration with LIGO?

Dr. Finke explained that he was inspired by the LIGO findings when he saw the connection between Ultraluminous X-Ray source formation rate and the Binary Black Hole merger rate, but he did not work together with LIGO.

What were you working on before gravitational waves?

Justin Finke said that he usually works on gamma ray jets shot out by Supermassive Black Holes. Dr. Finke commented that he did this research using the FERMI Gamma Ray Telescope, which circles the globe every 90 minutes in a low-Earth orbit.

Why did you choose to become an Astrophysicist?

Justin Finke joked that he did not have any big story that convinced him to become a physicist; he had always been interested in physics and math, and thought that astrophysics was the most interesting subject to research.

How did you end up working at the Navy Research Lab?

Dr. Finke recounted that, while going for his PhD, he collaborated with someone from the Navy Research Lab. The person Justin Finke worked with helped him get a job at the NRL, and is now Finke’s boss.

Breaking down the interview, Dr. Finke’s comments provide some good advice for aspiring physicists. Pursue the work that interests you, and interact with your fellow physicists. You never know where a work opportunity might come from, or when you’ll find inspiration for an interesting research subject, so always keep an open mind.