Times shown are in IST. CET is 4:30 hours behind, GMT is 5:30 hours behind, and Beijing time is 2:30 hours ahead, e.g. 3 PM IST = 10:30 AM CET= 9:30 AM GMT= 17:30 P Beijing Time
Day 1
Session Chair:
15:05 - 15:50
Title: Testing the effective field theory extension of general relativity with black hole binaries
Abstract: Gravitational waves from black hole binaries allow us to probe the gravitational interaction in a regime of strong curvature, allowing us to search for deviations from Einstein’s theory. To this end, it is important that we describe and model the effects of beyond-GR physics on gravitational-wave signals. In this talk, I will consider an Effective Field Theory (EFT) extension of GR with higher-derivative corrections, and I will discuss the signatures of the corrections on the inspiral. For metric theories, I will argue that finite-size effects provide the leading corrections during the early inspiral, dominating over the corrections to wave generation. I will then focus on the case of the tidal response of black holes. First, I will provide a complete characterization of the tidal Love numbers of nonrotating black holes in the EFT of GR by using the modified Teukolsky equation, a framework that also provides a systematic route to the rotating case. Then, I will consider the GW emission by a point particle orbiting a black hole in the EFT. Through an explicit computation using black hole perturbation theory, I obtain the gravitational wave amplitudes and the energy emission at infinity, showing that the leading correction to the GR prediction is universally given by the tidal Love numbers previously discussed. I will conclude by discussing open questions and future directions.
15:50 - 16:35
Title: New Physics in Gravitational-Wave Detectors: From Ultralight Fields to Primordial Black Holes
Abstract: Gravitational-wave detectors provide a new laboratory for testing fundamental physics and searching for phenomena beyond the standard astrophysical sources predicted by general relativity. In this talk, I will discuss how data from the LIGO–Virgo–KAGRA detectors can be used to probe dark matter across an enormous range of mass scales, from ultralight fields to macroscopic compact objects. I will first present results from a recent search using data from the fourth LIGO–Virgo–KAGRA observing run for ultralight scalar, vector, and tensor dark matter. Such fields can produce coherent, long-lived signals in gravitational-wave interferometers through interactions with the detector components, allowing the instruments themselves to act as direct dark-matter detectors. I will then discuss searches for long-duration gravitational waves from inspiraling planetary- and asteroid-mass ultra-compact objects, which provide a complementary probe of macroscopic dark matter such as primordial black holes. Finally, I will discuss searches for gravitational radiation from ultralight boson clouds around rotating black holes, where black-hole superradiance provides a qualitatively different connection between gravitational-wave observations and particle physics. Together, these examples demonstrate how precision gravitational-wave measurements can be used not only to test the dynamics of gravity, but also to search for new fields, exotic compact objects, and physics beyond the Standard Model.
Session Chair: Indrani Banerjee (NIT Rourkela)
Day 2
Session Chair :
15:00 - 15:45
Title: Dynamical Tidal Response of Compact Objects
Abstract: The tidal deformability of a gravitating object is characterized by a set of coefficients that quantify its response to external tidal perturbations. It is well known that the zero-frequency response coefficients—also known as the static tidal Love numbers of Schwarzschild black holes vanish identically in four-dimensional general relativity. At subleading orders in the adiabatic expansion, dissipative and conservative contributions become nonzero, capturing, respectively, horizon absorption and frequency-dependent corrections to the tidal Love numbers. Using the framework of point-particle effective field theory, I will present the calculation of the dynamical Love numbers of Schwarzschild black holes and neutron stars up to quartic order in frequency. In addition to the previously known logarithmic renormalization-group running, I will derive the scheme-dependent finite terms. Finally, if time permits, I will show that causality and positivity imply a series of nontrivial bounds on the dynamical Love-number couplings of neutron stars, which translate into constraints on their equation of state. This represents a first step toward establishing what I dub a CompactHedron: a systematic framework for deriving bounds on compact objects from microscopic principles.
Session Chair : Shubho R. Roy (IIT Hyderabad)