TITLE: Impact of primordial magnetic fields on matter power spectrum ABSTRACT: Primordial magnetic fields (PMFs) offer a simple explanation for the origin of galactic magnetic fields as well as of the purportedly detected magnetic fields in cosmic voids. In the talk, I discuss how PMFs' influence on structure formation can offer a complementary method to […]
TITLE: CMB limits on decaying dark matter: going beyond the ionization threshold ABSTRACT: The temperature and polarization anisotropies of the cosmic microwave background (CMB) have been used to set constraints on decaying dark matter models down to keV masses. In this talk, I will discuss recent work to extend these limits down into the sub-keV […]
Title: Binary black hole waveforms in the small mass ratio limit Abstract: Current gravitational-wave detectors are being upgraded, and plans are developing for future detectors with greater sensitivity over broader frequency bands. As instruments improve and develop, more cycles of sources’ gravitational waveforms will be measured with greater signal to noise ratio. Such higher fidelity […]
TITLE: Studying the Extreme Universe with Imaging Atmospheric Cherenkov Telescopes, ABSTRACT: The night sky is filled with flashes of blue "Cherenkov" light, which last for just a few billionths of a second. Invisible to our eyes, these flashes result from particle cascades in the Earth's atmosphere triggered by the arrival of a high energy cosmic […]
TITLE: Revisiting the axion-electron coupling ABSTRACT: In the presence of axion dark matter, fermion spins experience an “axion wind” torque and an “axioelectric” force. We investigate new experimental probes of these effects and find that magnetized analogs of multilayer dielectric haloscopes can explore orders of magnitude of new parameter space for the axion-electron coupling. We also […]
TITLE: Ghosts on the way to a QFT for gravity ABSTRACT: Ghosts have been a stumbling block in the development of a UV complete quantum field theory for gravity. We discuss how difficulties associated with ghosts are overcome in the context of 0+1d QFT. Obtaining a probability interpretation is the key issue, and for this […]
TITLE: Quasinormal Modes from Penrose Limits ABSTRACT: In this talk, I will explain how to describe quasinormal modes with a large real frequency using Penrose limits. To do so, I first recall relevant aspects of the Penrose limit, as well as the plane wave spacetimes that arise in this limit, to subsequently tie this together with […]
Title: Quantum near extremal black holes and anomalies Abstract: The Bekenstein–Hawking formula gives a coarse-grained count of the number of microstates of a black hole, and it is remarkable that it may sometimes be reproduced from a microscopic count in string theory. However, the standard approach (which we will briefly review) typically relies on supersymmetry by counting […]
Title: Fundamental Physics and Cosmology from Stellar Mass Binary Black Holes Abstract:The first three observing runs of the LIGO, Virgo, and KAGRA gravitational wave detectors produced a wealth of "firsts," including the first observation of multiple "ringdown" modes from a black hole---the remnant of the first-ever binary black hole merger, GW150914. Just like an excited […]
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 […]