Scientific Series

Quasars - accreting super-massive black holes - are the most luminous non-transient sources known and can be seen at redshifts of z > 7, when the Universe was just ~5% of its current age.  This implies that black holes with masses of up to ~10^9 M_Sun formed less than 800 Myr after the Big Bang, impossible under the default paradigm of Eddington-limited accretion onto stellar mass black holes.  The greatest barrier to understanding the formation and growth of these objects is the lack of data: quasars are very rare at these distances/times with fewer than ten known with z > 7 at present.  I will report on recent observational developments in this field, with a particular focus on the early results from the Euclid mission, for which the Wide Survey has the necessary combination of area, wavelength coverage and depth to increase the number of known quasars by an order of magnitude and to push to redshifts z > 8 and beyond.

In 2010, Kontsevich and Soibelman defined Cohomological Hall Algebras for quivers and potential as a mathematical construction of the algebra of BPS states. These algebras are modeled on the cohomology of vanishing cycles, which makes these algebras particularly hard to study but often result in interesting algebraic structures. A deformation of a particular case of them gives rise to a positive half of Maulik-Okounkov Yangians. The goal of my talk is to give an introduction to these ideas and explain how for the case of tripled cyclic quiver with canonical cubic potential, this algebra turns out to be one-half of the universal enveloping algebra of the Lie algebra of matrix differential operators on the torus, while its deformation turn out be one half of an explicit integral form of the Affine Yangian of gl(n).

I will introduce the Entanglement Bootstrap, a program to extract and understand the universal information characterizing a state of matter, starting from the local entanglement structure of a single representative state. This universal information is usually packaged in the form of a quantum field theory; the program therefore provides a surprising new perspective on quantum field theory. I will discuss what we can learn about gapped topological phases and their associated topological field theories, and about quantum critical points and their associated conformal field theories.

In this talk I will outline a fundamentally quantum description of bosonic dark matter from which the conventional classical-wave picture emerges when the mass is far below 10 eV. Exploiting fundamental results from quantum optics I will argue that the density matrix for dark matter is explicitly mixed. The formalism provides a continuous description of DM through the wave-particle transition, and using this I show how density fluctuations over various physical scales evolve between the two limits, with a unique behavior for DM emerging near the boundary of the wave and particle descriptions. If time permits, I will briefly describe how these effects would appear in axion haloscopes.

We are now firmly within the ALMA-inspired era of star formation studies. We have abundant high sensitivity and resolution observations of star-disk-outflow systems as well as the ability to perform complex high-resolution plasma astrophysics simulations of their formation. I review recent three-dimensional nonideal MHD simulations that reveal surprising new insights into the role of magnetic fields and magnetic field dissipation in creating outflows, arcs, and cavities on scales of hundreds to thousands of au. Magnetic fields are responsible for a complex inflow-outflow structure around a protostar. I end the talk with results that may answer the longstanding big question in star formation studies: what stops the mass infall on to a protostar?

It has been conjectured that the gravitational interaction may arise as an entropic force rather than as a result of virtual quanta exchange of a fundamental field. In this talk I will present a set of microscopic quantum models which realize this idea in detail. I will describe a simple mechanism by which Newton’s law of gravity arises from the extremization of the free energy of a collection of qubits. I will show both a local and non-local model version of the construction and discuss how to distinguish these entropic models from ordinary perturbative quantum gravity using existing observations and near term experiments. Based on 2502.17575 with Daniel Carney, Thilo Scharnhorst, Roshni Singh and Jacob M. Taylor.

Vertex operator algebras (VOAs) arise in many corners of supersymmetric quantum field theory. One particularly influential instance is in 4d N=2 superconformal field theories, whereby the VOA is realized as the cohomology of a suitable supercharge. Unitarity of the underlying SCFT imposes strong constraints on the structure of the resulting VOA. In this talk, I will describe one aspect of how the unitary of the underlying SCFT constrains this VOA: in the context of superconformal gauge theories, the resulting BRST complex shares a striking resemblance to the de Rham complex of a compact Kähler manifolds. I will finish with several consequences of this observation, e.g. the formality of these BRST complexes as in the work of Deligne-Griffiths-Morgan-Sullivan on compact Kähler manifold. This is based on work in progress with C. Beem.

We introduce 'Lattice Cosmology’ as an emergent field encompassing a set of techniques capable of solving the non-linear dynamics of interactive fields in an expanding Universe. As a demonstration of the power of these techniques, we solve two very different problems of early Universe cosmology: i) the non-linear dynamics of axion inflation, and ii) the dynamics and gravitational wave emission of cosmic string loops.