Astronomy Tea Talk

Speaker 1:  John Franklin Crenshaw (Rubin Postdoctoral Fellow; KIPAC, Stanford University)

Title: Mapping Cosmic Structure at z = 3–5 with the Rubin Observatory

Abstract: The Rubin Observatory's LSST will open an unprecedented window onto the high-redshift Universe. Its unique combination of depth, sky coverage, and multi-band imaging will enable the discovery of hundreds of millions of galaxies at redshifts (2.5 < z < 5.5) using the Lyman-break "dropout" technique, in which ultraviolet light from distant galaxies is absorbed by neutral hydrogen in the intergalactic medium. Together, these galaxies will provide the largest map ever constructed of cosmic structure during an era when the Universe was only about 1–2 billion years old. I will discuss how the clustering of these galaxies and their cross-correlation with CMB lensing can probe the growth of structure and constrain cosmology at high redshift. I will present forecasts for the cosmological constraints expected from LSST, and discuss photo-z calibration and survey non-uniformity, the two biggest observational challenges that must be overcome to realize the full cosmological potential of this remarkable dataset.

Speaker 2: Manami Roy (CCAP Fellow; Ohio State University)

Title: Cosmic Rays: The Hidden Architects of Galactic Evolution

Abstract:  Cosmic-ray (CR) transport and its impact on different environment of galaxies remain an open question in the field of galaxy evolution. In the interstellar medium (ISM), puzzling gamma-ray observations continue to challenge our understanding of CR propagation, while in the circumgalactic medium (CGM), limited observations make it difficult to constrain the role of CRs. The problem is further compounded by the enormous dynamic range involved: the relevant physical scales span over ten orders of magnitude, from AU-scale CR gyroradii to halo-scale processes extending hundreds of kiloparsecs.  In my talk, I will discuss impact of CR physics on large galaxy scale (~kpc) along with small pc scale. I will show how CRs influence the dynamics and thermodynamics of the multiphase CGM of the galaxies and can significantly alter the evolution of ram-pressure stripped clouds from their satellite galaxy. Then, I will shift to small scale and discuss how observable non-thermal emission produced by CR populations can be spatially offset from their acceleration sites.