Collaborative Research: Tidal Disruption of Stars in Galaxy Centers: Connecting Models to Observations

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

Abstract for 1615881/Ramirez-Ruiz + 1616754/Kasen 1. Galaxies like our own Milky Way are vast collections of hundreds of billions of stars orbiting in a disk perhaps 100,000 light-years in diameter. Lurking in the centers of many and perhaps all galaxies are supermassive black holes?mysterious objects containing millions or billions of times as much mass as our own Sun, but crammed into a volume that would fit easily within the inner solar system. In the past few years, astronomers have discovered luminous flares emanating from the core regions of nearby galaxies. These are thought to originate from the disruption of individual stars that were orbiting so close to the black hole that they were ripped apart by its strong gravitational force. The energy emitted as the remains of the star fall into the black hole produces the luminous flare. The collaborators on this project will carry out detailed numerical modeling of these events and will make publicly available their computer codes. The collaborators also plan to make their work accessible to a wide audience by teaming experts with students in the visual arts and digital media to produce visual simulations of great power and beauty. In addition, they will participate in a strong program to recruit and mentor astronomy students from under-represented groups. 2. Over the past several years, wide-field transient surveys have begun to deliver more and better data about tidal disruption events (TDEs). A TDE is produced when a star is tidally disrupted by a supermassive black hole (SMBH) in the core of a galaxy. Because the theoretical understanding of such events remains incomplete, the collaborators will bring together experts in numerical hydrodynamics and non-equilibrium radiative transfer to study how matter from the tidally disrupted star loses kinetic energy and accretes onto the SMBH, identify the radiative processes that generate the X-ray/ultraviolet/optical spectra and light curves of TDEs, develop a numerical toolset to be used in analyzing TDEs, and apply it to constrain the properties of the star and the SMBH in observed events. For TDEs with well-resolved light curves, their models will enable a better characterization of the SMBHs and the dense stellar clusters that surround them. Building upon existing strengths of the partner institutions, the collaborators will also cross-fertilize the training of computational scientists and students in the visual arts and digital media using state-of-the-art astrophysical simulations as common ground. The resulting visual products will be used to disseminate the results, help to inform the general public about science and the universe, and provide raw material for science curricula, documentaries, and astronomy presentations. The investigators will also continue their program to recruit and mentor astronomy students from under-represented groups.