Callum Fairbairn- Institute for Advanced Study

Title: Eccentric perturber-disk interactions: linear theory and numerical verification

Abstract: The interaction between a gravitationally perturbing body and the surrounding gas is a fundamental astrophysical problem. In a homogeneous gaseous environment, the resulting wake response leads to the classical gas dynamical friction results. However, in rotationally supported systems dominated by a central mass, strong shear flows alter this picture. For example, the orbital evolution of planets in protoplanetary disks or stellar-mass black holes in AGN disks is now mediated by the launching of spiral density waves. While much attention has been given to waves generated by circular orbits, perturbers may also form or be excited onto eccentric trajectories. In this talk, I will review our semi-analytical, global, linear framework, which describes the wake morphology of an eccentric perturber in a Keplerian shear flow. Furthermore, we apply this tool to conduct a parameter space survey over disk properties and eccentricity amplitudes to quantify the back-reaction torque driving orbital evolution. We identify a transition in behavior as increasing eccentricity induces transonic radial motions, leading to torque reversal, stalling of inward migration, and a slowdown in eccentricity damping. These semi-analytical results have been rigorously validated using fully nonlinear hydrodynamical simulations, which we have extended to the high-eccentricity regime, revealing highly complex substructures within the gas disk. The agreement at high eccentricity values suggests that linear theory is remarkably well converged even for the most extreme orbits considered.

David Coulter- Space Telescope Science Institute

Title: SN Eos: A Multiply-Imaged, 30x Magnified SN Near the Epoch of Reionization

Abstract: On September 1, 2025 the Vast Exploration for Nascent, Unexplored Sources program (VENUS) discovered a multiply-imaged supernova (SN) in JWST imaging of the galaxy cluster, MACS1931 (z~0.35). At the site of the lensed images, contemporaneous VLT/MUSE data show Lyman alpha emission from the host, placing the lensed system at a spectroscopic redshift = 5.13. We dub this candidate SN Eos – named after the Titan goddess of dawn. The two images of Eos are magnified by ~30x, are nearly simultaneous given their expected time delays (~hours in the rest frame), and are in excellent agreement with an SN IIP in the plateau phase of its light curve evolution in a low-metallicity environment. We present this discovery and our follow-up data, show that SN Eos offers a true test of whether local, low-metallicity SNe IIP are indeed good high-z analogues, and discuss the unique properties of a highly magnified SN II at z > 5. We emphasize that only through an observatory like JWST, paired with a dedicated lensing survey like VENUS, can we push SN discovery and characterization to the Epoch of Reionization.