Karim: Cosmology with Emission-Line Galaxies: A case study with the Dark Energy Spectroscopic Instrument / Silva-Feaver: Realizing an r <= 0.01 Inflation Survey with the Simons Observatory

Dec 02, 2022 - 10:40 am to 11:30 am

SLAC, Kavli Auditorium *note change in location*

Tanveer Karim (Harvard University) / Maximiliano Silva-Feaver (UC San Diego) zoom https://stanford.zoom.us/j/550904854

Zoom info: https://stanford.zoom.us/j/550904854


Emission-Line Galaxies (ELGs) are star-forming galaxies that were numerous in the early Universe, as the cosmic star formation rate peaks around z ~ 2. As such, they will serve as the chief tracer class to probe large-scale structures in the z > 1 Universe for upcoming surveys such as the Dark Energy Spectroscopic Instrument (DESI), Rubin LSST, and Euclid. However, as they are novel tracers, how their systematics affect cosmological interpretation has been so far relatively unexplored. In this talk, I will present the motivation for the prospect of ELGs, especially in the context of cross-correlation analysis, using DESI-like ELGs and the Planck CMB lensing as case studies. I will discuss how different theoretical and observational ELG systematics bias cosmological interpretation and conclude with ways to deal with these issues.

The Simons Observatory (SO) is a set of 4 Cosmic Microwave Background (CMB) telescopes sited in the Atacama desert in Chile, scheduled to begin operations in 2023. The SO will be the largest CMB observatory to date and will provide some of the most constraining measurements of physics beyond the standard model and cosmology. The SO aims to produce the tightest constraints on the amplitude of primordial gravitational waves, the sum of the neutrino masses, the existence of relativistic species beyond the three neutrinos, and the growth of large-scale structure. The ambitious science goals of the SO drove an instrumental design with many cryogenic (100mK) sensors, which required a significant advancement in the multiplexing factor (number of sensors read out per readout circuit in the telescope). The SO employs the Microwave SQUID Multiplexer (mu-mux), and the room temperature digital signal processing electronics, the SLAC Microresonator RF (SMuRF) electronics, enabling a multiplexing factor of 1000. The SO represents the first at-scale demonstration of these technologies and is a significant achievement for mm and sub-mm cryogenic sensor readout. Another enabling technology for the primordial gravitational wave search within SO is the integration of a continuously rotating broadband cryogenic half-wave plate (HWP) to mitigate contamination from mm-wave emission from the atmosphere. Few CMB observatories have deployed with HWPs and none with the SO design. The improvement in bandwidth and reduction in systematic contamination enabled by the SO HWP design drove a significant experimental effort and serves as a crucial demonstration for next-generation CMB observatories. We have fully integrated one of the SO telescopes with multiplexed readout and a rotating HWP in the lab at UC San Diego. We present testing of the software pipeline on time-ordered data from pre-ship measurements at UC San Diego, an essential milestone for validating the hardware performance and analysis software readiness for deployment in 2023. The technical and software hurdles overcome thus far situate the SO to provide exquisite constraints on inflation, neutrino properties, and the growth of large-scale structure in the coming decade.