Dr. Zachariah Etienne is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the University of Illinois at Urbana-Champaign (UIUC). Dr. Etienne will perform fully general relativistic simulations of black hole-black hole binary (BHBH) mergers in gaseous environments, as well as binary neutron star-neutron star (NSNS), black hole-neutron star (BHNS), and white dwarf-neutron star (WDNS) mergers. To model these systems realistically, the PI will develop massively parallel, cutting-edge simulation software, incorporating new physics for the first time, such as realistic equations of state, radiation transport, magnetohydrodynamics, and black hole spin. NSNS and BHNS binary mergers are among the most promising candidates for powering gamma-ray bursts. Moreover, electromagnetic radiation signatures of these compact binary mergers, as well as binary black holes in gaseous environments, are potentially detectable by conventional telescopes, such as the Fermi Gamma-ray Space Telescope, the Hubble Space Telescope, and the proposed Large Synoptic Survey Telescope, among others.
Dr. Etienne will also spearhead an annual seven-school lecture tour. Dr. Etienne's lectures will be prepared on two levels--one designed for general physical science classes and the other for physics and advanced-placement physics courses. The lectures will be supplemented by computer-generated movies of Dr. Etienne's compact binary merger simulations, prepared by the PI in cooperation with the Illinois numerical relativity group's Research Experience for Undergraduates visualization team. In conjunction with the UIUC Physics Illinois Partnership Program and his lecture tour, the PI will develop a website that provides an interactive, multiple "mini-lesson" introduction to his research for students and teachers.
To maintain its worldwide leadership in astronomy and astrophyics research, the United States has invested greatly in the next generation of astronomical observatories. But the insights we gain from these observations will be limited by our theoretical understanding. This is where the PI's research fits in. The PI aims to produce the first self-consistent theoretical models of some of the most spectacular and mysterious astronomical phenomena we observe, but accurate theoretical models are extremely challenging to produce, requiring large-scale simulations on some of the fastest supercomputers in the world. Over the past years as an NSF Astronomy and Astrophysics Postdoctoral Fellow, the PI has worked to greatly improve simulations of important astrophysical phenomena for current and next generation astronomical observatories. This difficult research has required the development of new techniques for modeling the critically important physics that drive these phenomena. The end goal is to model some of the most energetic phenomena in the cosmos, such as gamma-ray and gravitational wave bursts, which are widely believed to be driven by the interactions and mergers of black holes, neutron stars, and white dwarfs. In the extreme violence of merger, these incredibly dense objects are capable of generating copious amounts of gravitational and electromagnetic radiation detectable by current and planned observatories. The PI's latest simulations have helped to move his research field, numerical relativity, beyond proof-of-principle astrophysical simulations and into the realm of informing and improving the theory explaining these phenomena, which are thought to be driven by interacting black holes, neutron stars, and white dwarfs. Here are the two most significant results from projects led by the PI: 1) Developed a novel technique for modeling magnetic fields within numerical relativity simulations that involve black holes, neutron stars, and white dwarfs. Other numerical relativity research groups have subsequently adopted this new technique in their own simulation software. [Published in the following scientific journal articles: PRD 82, 084031 (2010); PRD 85, 024013 (2012)]. 2) When a neutron star merges with a black hole, it may disrupt and form a disk around the black hole. The PI and collaborators applied the above technique and found that the magnetic fields in this disk are structured in such a way as to make it difficult for such a merger to form a gamma-ray burst. [Published in the following scientific journal articles: PRD 86, 084026 (2012); PRD 85, 064029 (2012)]. This grant has an impact beyond its research focus. The PI has built on his many volunteer experiences lecturing to high school and middle school students by spearheading an annual multi-school lecture tour at underserved high schools in predominantly rural southern Indiana. Because there are no major research institutions nearby, before the PI visited these schools, none of the students had interacted with a professional scientist before. The PI gave lectures to about 12 classes at four schools over the past year, including physics (both AP and non-AP), calculus, chemistry, and physical science classes. Over the past years, the PI has increased the number of classrooms he has visited and thus students he has reached. The lectures have undergone significant improvements over the past years, and have evolved into the following basic outline. They begin with a short "Career Day"-style introduction, describing the PI's career path. This is followed by a 5 minute discussion on the topic "What is Science and What Motivates Scientists?", as most students are not regularly reminded about what motivates scientific research and are therefore not easily familiar with the motivations. Next, the basic principles behind special relativity are described (15 minutes). It was this material that ultimately motivated the PI (as a high schooler) to pursue science as a career, and this section has evolved into the centerpiece of the lecture, sparking widespread classroom discussion. After the latest lecture tour, high school teachers reported to the PI with some surprise that the most active student participants in these discussions are often the ones who do not normally speak up in class. It is the PI's hope that these students, who happen to be underrepresented in the sciences, will be encouraged by his lecture to consider pursuing science as a career option. In addition, after the lecture tour, some students who had already planned to pursue careers in the sciences contacted the PI, asking for college course advice, to which the PI replied with recommendations. The PI's outreach lecture tour has a history well before this grant, and this grant has provided him a key opportunity to expand and improve the lectures, greatly increasing their impact. Over the coming years, he intends to expand this outreach, likely applying for future funding from the NSF for continued support.
