CAREER: Exploring Strong-field Gravity and Dense Matter Physics through Gravitational-wave Observations

The overarching goal of this award is to reveal how accurately one can probe fundamental physics (in particular gravitational and nuclear physics) and understand neutron star astrophysics with current and future gravitational wave and multimessenger observations. On the gravitational physics front, the PI will develop an artificial intelligence algorithm to perform strong-field tests of gravity with gravitational waves in a model-independent way that involves multiple deviation parameters from General Relativity. On the nuclear physics front, the PI will focus on probing the crystallized quark core inside neutron stars through characteristic stellar oscillations that are excited in the interface between the solid quark core and fluid hadronic envelope. On the astrophysics front, the PI will focus on binaries containing magnetars (neutron stars having magnetic field strength that are roughly 13 orders of magnitude stronger than typical fridge magnets) and study how well one can learn binary properties, including the magnetic field strength of magnetars, through multimessenger observations between gravitational-wave and radio observations. The long-term educational goal of the award is to connect with potential next-generation scientists and convey the beauty and excitement of physics, in particular General Relativity. The PI will attempt a three-pronged project to study neutron stars and tests of General Relativity. On the gravitational physics prong, the PI will adopt machine-learning algorithms called conditional variational autoencoder and normalizing flow. The PI will first create working codes within General Relativity to reproduce some existing results and next update the codes to handle theories beyond General Relativity. On the nuclear physics prong, the PI will construct stellar solutions with non-vanishing elasticity in the core and perturb them to find oscillation frequencies. On the astrophysics prong, the PI will construct neutron star solutions with a realistic magnetic-field configuration called twisted-torus, calculate the stellar quadrupole moment and the magnetic dipole moment, and carry out parameter estimation studies to reveal how accurately one can measure the magnetic field strength in binary neutron stars through gravitational wave observations. To achieve the educational goal, the PI's team will develop an online game on General Relativity and gravitational waves to reach out to young players across the world. In the game instructions, the PI will provide a brief description of General Relativity, black holes, and gravitational waves, conveying the excitement and key aspects of recent Nobel-prize-winning physics. University of Virginia undergraduate students will be involved in game development, integrating the research and educational activities. The PI will make the source codes publicly available so that anyone can develop their own games. The achievement will be advertised at annual meetings for physics teachers in Virginia and around and through a public article and audiobook that will reach over 55,000 readers globally including STEM minority regions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.