Astro Tuesday: Sanjana Curtis and Priscilla Frisch

12:00–1:00 pm ERC 401

Sanjana Curtis "Heavy element nucleosynthesis and kilonovae from compact object mergers"

The merger of compact object binaries is typically accompanied by the ejection of neutron-rich matter that undergoes r-process nucleosynthesis, producing some of the heaviest elements in our Universe and powering an electromagnetic transient called a kilonova. While this basic picture was confirmed by the detection of the kilonova counterpart to GW170817, significant uncertainties remain when it comes to the details of heavy element production, with respect to both hydrodynamical modeling and nuclear physics. The post-merger evolution of the merger remnant is key to linking numerical simulations with astrophysical observations but remains the most uncertain piece of this puzzle. In this talk, I will present nucleosynthesis and kilonova predictions for binary neutron star mergers and black hole-neutron star mergers based on general-relativistic magnetohydrodynamic models of the post-merger phase. These models include relevant neutrino physics crucial for setting the electron fraction of the ejecta, and in turn, the heavy element abundances. I will also discuss the significance of our results in light of the blue kilonova component associated with GW170817. Detailed long-term modeling of these post-merger outflows is indispensable for understanding past and future observations of kilonovae and finally solving the mystery of the origin of heavy elements.

Priscilla Frisch "Whence the Interstellar Magnetic Field Shaping the Heliosphere"

The Interstellar Boundary EXplorer (IBEX) spacecraft returned an unprecedented diagnostic of the interstellar magnetic field (ISMF) shaping the heliosphere in the form of the IBEX ``ribbon'' of energetic neutral atoms. An effort to understand the IBEX ISMF was undertaken through mapping of the very local ISMF using measurements of starlight linearly polarized by foreground aligned interstellar dust grains. High-sensitivity data collected at over seven observatories throughout the world, by a large group of international astronomers, is the basis of our detailed study of the configuration of the very local ISMF (Frisch et al. 2022).  Among findings are that (1) the heliosphere samples a larger scale ISMF that extends throughout the nearest 40 pc.  (2) A distinct polarization filament extends through the heliosphere nose direction and the upwind direction of large interstellar grains flowing through the heliosphere and is aligned with Voyager kHz emissions, three QSO local scattering screens, and the Copi et al. 2007 CMB components. (3) A CMB dark spot is nearly aligned with IBEX ISMF. (4) A magnetic filament separates several local interstellar clouds.  (5) Two large magnetic arcs are centered on the direction of the heliotail. Credits: Over half of the new polarization data utilized in this study were collected by the group of Vilppu Piirola at the University of Turku, 20014 Turku, Finland.

Event Type


May 17