Title: How Much Do We Understand About Early Galaxy Formation? Abstract: The “Cosmic Dawn” of galaxy formation is one of the frontiers of modern astronomy. In the past two years, JWST has provided tantalizing clues about sources in the first several hundred million years of the Universe’s history that challenge our understanding this era, including […]
Title: Universality in a black hole ringing: excitation factors and greybody factors, Abstract: The ringdown gravitational waves emitted by a ringing black hole areimportant for testing strong gravity physics. However, achievingprecise detection requires not only advances in observationaltechniques but also a deeper theoretical understanding of ringdown orquasinormal-mode (QNM) excitation. In this talk, I will explain theuniversality […]
Title: Black holes in space and the "lab": from theory to practice Abstract: This talk focuses on recent theoretical developments in black holes and gravity using techniques from quantum field theory. I will begin by demonstrating how perturbative quantum field theory can be employed to compute the gravitational waveforms generated by astrophysical black holes. Next, I will […]
Title: The Power of Non-invertible Symmetry, Abstract: I will discuss recent advances in a novel class of symmetries in quantum field theories and quantum lattice models, known as non-invertible symmetries. Unlike conventional symmetries governed by Wigner's theorem, these are implemented by conserved operators that have no inverse, challenging and extending the traditional paradigm of symmetry in physics. I […]
Title: From quantum information to black holes and cosmology, Abstract: Black holes have not just become laboratories for astronomers, but also present some of the deepest unsolved problems in theoretical physics. During the past decade surprising connections have been made between ideas from quantum information and gravitational physics. In this talk I will explain several aspects […]
Title: Cauchy-characteristic matching, Abstract: Cauchy-characteristic matching is a novel numerical-relativity technique that enables the evolution of Einstein’s equations on an effectively infinite computational domain. In this talk, I will present our recent successful applications of this method to binary black hole mergers, and demonstrate its transformative potential for modeling tail and memory effects in eccentric binaries.
Title: Where is tree-level string theory? Abstract: Tree-level string theory extends Einstein gravity by an infinite set of massive higher spin particles. From a purely spacetime perspective (if we didn’t know about the worldsheet picture) the consistency of string amplitudes would appear truly miraculous. This prompts the question: is string theory the unique framework for a higher […]
TITLE: Cosmological results from the Dark Energy Spectroscopic Instrument, ABSTRACT: A quarter-century after the discovery of the accelerated expansion of theuniverse, the constraints on dark energy that powers this acceleration havebecome very good, but physical nature of dark energy remains elusive. I willpresent and discuss cosmological results from the measurement of baryonacoustic oscillations (BAO) in […]
Worldline effective theories and gravitational dynamicsWorldline effective theories are incredibly useful tools for studying the dynamics of spatially compact systems, with gravitational binaries being a perfect example. In particular they allow for the import of many tools from quantum field theory, eg. Feynman diagrams, loop integration techniques, dimensional regularization, renormalization group, etc. Work in recent […]
Early Galaxies from Rare Inflationary Processes Rare Poisson processes during cosmic inflation can generically lead to rare, high-redshift (z) galaxies. Focusing on inflationary heavy particle production as one example of a Poisson process, I will derive the redshift distribution, masses, and number densities of such early galaxies. The James Webb Space Telescope (JWST) is a powerful probe […]
Theoretical approaches to cosmic tensions, Abstract: The Hubble and weak-lensing S8 tensions in cosmology perhaps hint at new physics beyond LCDM. I have extensively investigated these anomalies, proposing the early dark energy (EDE) solution to the Hubble tension. Although EDE has had some successes, there are challenges yet - improving EDE's underlying fundamental model, constraining […]
Title: Scalar Relics from a Hot Big Bang in Theories of Fifth Forces, Abstract: Fifth force and equivalence principle tests search for new interactions by precisely measuring forces between macroscopic collections of atoms and molecules and their properties under free fall. In contrast, the early Universe plasma probes these interactions at a more fundamental level. […]