Supermassive Star Collapse: Probing a Pathway to Supermassive Black Hole Formation

Moran Christine C, Columbus OH

Investigators

Abstract

Christine Corbett Moran is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the California Institute of Technology. Upcoming space missions will enable astronomers to observationally test theoretical models for supermassive black hole (SMBH) growth for the first time. How SMBHs formed so quickly, during the first billion years of the Universe, remains a central puzzle of cosmology and galaxy evolution. One candidate formation pathway is through supermassive stars (SMSs) that could have formed in the direct collapse of primordial gas clouds. At the end of their lifetimes, the collapse of SMSs may result in black holes with seed masses large enough to be the progenitors of SMBHs; powerful thermonuclear explosions with no remnants; or black hole-explosion combinations. Yet our understanding of SMS collapse, its set of outcomes, and their signatures is in its infancy. Moran's research program will comprehensively address SMS evolution, producing predictions that can be tested by upcoming missions to help untangle the formation channel of SMBHs. Moran's program also includes a significant educational component, which will give a computing school, the Summer Space Programming Challenge to Pasadena area high school students and teachers. Much theoretical work is still needed to understand SMS collapse/explosion dynamics and to predict their observational multimessenger (electromagnetic, gravitational wave, neutrino, nucleosynthetic) signatures in preparation and support of upcoming space missions such as the NASA James Webb Space Telescope, the NASA Wide-Field Infrared Survey Telescope, and the ESA Euclid mission. SMS collapse is a promising pathway to SMBH formation, yet its simulation with the necessary microphysics (stellar equation of state, nuclear reactions) and approximate or full general relativity has thus far been limited to spherical or axial symmetry, completely ignoring magnetic fields and 3D dynamics. Lightcurve and spectral modeling has only been performed for a single SMS explosion model. Moran's research program will comprehensively address SMS evolution through collapse and potential explosion in 3D general relativistic magnetohydrodynamic simulations with detailed microphysics, producing observables across the SMS parameter space spanned by mass, metallicity, rotation, and magnetization. Necessary code development in support of the program will be released as open source. The broader impact of the program includes the Summer Space Programming Challenge, in which students and teachers will gain further interest in space research, concrete computational skills, a project portfolio, and open source curriculum materials.