Nir Shaviv's research focuses on extreme astrophysical systems and their stability under intense radiation pressure. He showed that in highly luminous stars, where classical predictions suggest radiation should overwhelm gravity, the presence of porous atmospheres allows radiation to escape more efficiently, reducing outward force and stabilizing the system. He also discovered atmospheric instabilities that lead to such structures. These insights have advanced our understanding of stellar winds, classical novae, and high-accretion-rate disks, and led to the first systematic prediction and discovery of precursor brightenings occurring a few years to a few months before supernova explosions—a finding published in Nature.
A second major area of his research explores high-energy astrophysics, particularly the role of galactic cosmic rays—energetic particles from supernovae—in both helping understand the Milky Way’s structure and influencing Earth’s climate. Cosmic rays are the dominant source of atmospheric ionization and play a role in cloud condensation processes. Over 25 years, Shaviv has led an interdisciplinary program combining empirical evidence, theoretical models, lab experiments, and climate modeling to study this influence. His work includes reconstructing variations in cosmic ray flux from iron meteorites, identifying seven spiral-arm crossings of the solar system over the past billion years, and showing their correlation with ice age epochs. These results provide new tools to track the solar system’s vertical and radial motion through the Galaxy and even to estimate the dark matter density in the Galactic plane. Beyond these core areas, he has also contributed to neutron star physics, the identification of a novel supernova type arising from white dwarf–neutron star mergers, and other phenomena in physics and beyond.