KIPAC Tea Talk: Seeing the Invisible -- X-ray, Optical, and Infrared Variability as Probes of Accretion and Jet Physics in Low Luminosity AGNs / Constraining Inflation with the CMB: From Cosmological Colliders to Open Quantum Systems

Ford Abstract: Supermassive black holes (SMBHs) influence their galactic environments through mass inflow and outflow processes, yet most nearby SMBHs accrete material very inefficiently. In this talk, I will focus on these “picky eaters,” known as low-luminosity active galactic nuclei (LLAGNs), which accrete at highly sub-Eddington rates (~< 10^-6--10^-7 LEdd). LLAGNs are the most common form of AGN in the local Universe, and they are among the most promising targets for future event-horizon-scale imaging. I will discuss recent high-cadence, multi-wavelength monitoring with NICER, TESS, and other instruments to characterize the variability and underlying emission mechanisms of LLAGNs also observed by the Event Horizon Telescope. Pushing to even lower accretion rates (~10^-8 LEdd), our local SMBH, Sgr A*, exists in a predominantly quiescent state punctuated by flaring episodes. I will highlight recent multi-wavelength Sgr A* flare discoveries, including the first detected mid-infrared flare. Finally, I will present new JWST measurements of Sgr A*’s fuel reservoir at sub-parsec scales. Together, these observations provide a multi-wavelength view of how “picky” SMBHs accrete, radiate, and interact with their galactic environments.

Suman Abstract: The Cosmic Microwave Background (CMB) offers a unique window into an extremely high-energy physics of the early universe. While the standard paradigm of single-field inflation successfully explains the origin of primordial fluctuations, the exact particle physics driving this epoch remains unknown. In this talk, I will demonstrate how higher-order CMB statistics connects high-energy theory with cosmological observations. First, I will discuss the cosmological collider program, where heavy fields present during inflation leave distinct, oscillatory imprints on primordial non-Gaussianities. I will present recent work translating these theoretical signatures into concrete observational constraints on the mass and spin of new particles in the early universe. Second, I will approach inflation from the perspective of open quantum systems. Within the framework of an Open Effective Field Theory of Inflation, we can model dissipative inflation, wherein the inflatoin interacts with an environmental bath. I will highlight recent and ongoing work that jointly utilizes the CMB power spectrum and bispectrum to place robust constraints on these dissipative dynamics. Ultimately, this seminar will illustrate how precision cosmological data can be used to constrain the parameter space of complex inflationary models and probe fundamental physics at energy scales far beyond the reach of terrestrial accelerators.