Macroscopic Effects of the Quantum Conformal Anomaly: Scalar Gravitational Waves, Black Holes, and Dark Energy
In the second lecture, I will extend the previous discussion to gravity, and show that the conformal trace anomaly must play a special role in the effective field theory of low energy gravity.
In this first of two lectures, intended to be a pedagogical introduction, I will review the quantum field theory origin of anomalies starting with the more familiar example of the axial anomaly in QED, emphasizing the infrared effects and the appearance of a two-particle massless state, similar to a Cooper pairing in superconductor, associated with both the axial and conformal anomalies in two and four dimensions.
A key prediction of the Lambda CDM framework of structure formation is that a host halo containing a Milky Way sized disk galaxy should contain hundreds of thousands of sub-dwarf galaxy mass dark matter subhalos. Devoid of stars, these substructures remain undetected. Detecting them will not only corroborate the existence of dark matter but also give crucial information on the particle nature of dark matter and how they cluster at small scale. Cold stellar streams originate when globular clusters are tidally disrupted in the Milky Way potential.
Line Intensity Mapping has emerged as a powerful tool to probe the large-scale structure across redshift, with the potential to shed light on dark energy at low redshift and the cosmic dawn and reionization process at high redshift. Multiple spectral lines, including the redshifted 21cm, CO, [CII], H-alpha, and Lyman-alpha emissions, are promising tracers in the intensity mapping regime, with several experiments on-going or in the planning. I will discuss results from current pilot programs, prospects for the upcoming TIME experiment, and the outlook of future space missions such as SPHER
Stars orbiting in the halo of our galaxy, the Milky Way, are a window into the distribution of dark matter. In particular, tidally disrupted star clusters, which produce thin stellar streams, are optimal tracers of matter. Based on a Fisher-information calculation, we expect that the current data on the known Milky Way streams should constrain the radial profile and the shape of the inner halo to a precision of a few percent. In addition, stellar streams retain a detailed record of the matter field on small scales.
In galaxy redshift surveys, the line-of-sight velocity information is encoded in the observed redshift as a Doppler component that radially distorts the galaxy positions. The linear component of such `Redshift-Space Distortions' (RSD) is directly proportional to the growth rate of structure, f(z), and motivates the interest in RSD as a powerful way to constrain gravity. However, the non-linear evolution of the density and velocity fields requires the use of sophisticated theoretical models to extract reliable cosmological information from quasi-linear scales.
Gravitational lensing has long served as a unique probe of the growth of structure, which is sensitive on large scales to the properties of dark energy and gravity. In particular, lensing is instrumental in forming the statistic E_G, which is constructed to measure the growth rate of structure in a way independent of galaxy clustering bias. Measurements of E_G using both CMB lensing and galaxy lensing have proliferated, but new challenges await as the data from upcoming surveys become more precise. One such challenge is the bias on E_G due to the inhomogeneous magnification of gala
One of the most important discoveries of the 20th century has been the finding of neutrino oscillations. That phenomena implies that neutrinos are massive and shows the existence of physics beyond the standard model. Fundamental questions associated to this discovery are: what are the absolute neutrino masses? and what is their hierarchy? In this talk I will discuss how to use cosmological observables to answer these questions. I will first show one of the predictions of the Big Bang theory: the existence of a cosmic neutrino background.
I will first outline an effective field theory for cosmology (EFTC) that is based on the Standard Model coupled to General Relativity and improved with Weyl symmetry.
Burst phenomena are ubiquitous in astrophysics. Understanding the origin of bright and rapid bursts, like FRBs, is an important goal of contemporary astrophysics. We apply Dicke's superradiance, a coherent quantum mechanical radiation mechanism, to explain these burst phenomena. We show that bursts lasting from a few milliseconds (FRBs) to a few years (e.g. OH masers) can be produced by very large groups of entangled atoms/molecules. This is in contrast with the common assumption that, in the interstellar medium, the atoms/molecules in a radiating gas act independently from each other.