The Simons Observatory: Science Goals and Forecasts for the Enhanced Large Aperture Telescope

Abstract: We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply most of the observatory's power. The LAT survey will cover about 60% of the sky at a regular observing cadence, with five times the angular resolution and ten times the map depth of Planck. The science goals are to: (1) determine the physical conditions in the early universe and constrain the existence of new light particles; (2) measure the integrated distribution of mass, electron pressure, and electron momentum in the late-time universe, and, in combination with optical surveys, determine the neutrino mass and the effects of dark energy via tomographic measurements of the growth of structure at $z < 3$; (3) measure the distribution of electron density and pressure around galaxy groups and clusters, and calibrate the effects of energy input from galaxy formation on the surrounding environment; (4) produce a sample of more than 30,000 galaxy clusters, and more than 100,000 extragalactic millimeter sources, including regularly sampled AGN light-curves, to study these sources and their emission physics; (5) measure the polarized emission from magnetically aligned dust grains in our Galaxy, to study the properties of dust and the role of magnetic fields in star formation; (6) constrain asteroid regoliths, search for Trans-Neptunian Objects, and either detect or eliminate large portions of the phase space in the search for Planet 9; and (7) provide a powerful new window into the transient universe on time scales of minutes to years, concurrent with observations from Rubin of overlapping sky.

Overview of the Simons Observatory Paper on Science Goals and Forecasts

The paper "The Simons Observatory: Science Goals and Forecasts for the Enhanced Large Aperture Telescope" elaborates on the scientific objectives and projected outcomes for the Simons Observatory's (SO) Large Aperture Telescope (LAT). This document highlights technological enhancements and scientific potential, delineating a comprehensive framework for future observations up to the year 2034.

Key Developments

The paper outlines significant upgrades planned for the SO, notably the expansion of the LAT's mapping capabilities. The Observatory will feature 30,000 additional detectors, effectively doubling its mapping speed. This will allow SO to achieve a tenfold improvement in map depth and fivefold enhancement in angular resolution compared to the previous {\it Planck} satellite. Infrastructural enhancements, such as a photovoltaic power system and an automated data reduction pipeline, are discussed, indicating the Observatory's preparedness for sustained long-term operation.

Scientific Objectives

The paper identifies several key scientific objectives that aim to address foundational questions in cosmology, astrophysics, and planetary science.

1. Early Universe Conditions: SO aims to probe the physical conditions of the early universe, offering constraints on new light particle existence through improved measurements of primordial power spectra, spectral indices, and Gaussianity.
2. Structure Growth and Dark Energy: By leveraging optical surveys, the Observatory will measure mass distributions and electron pressure in the universe to elucidate neutrino masses and the role of dark energy via tomographic analyses.
3. Galaxy Groups and Clusters: SO will study the distribution of electron density and pressure around galaxy formations, assessing the impact of energetic processes from galaxy formation on their environments.
4. Trans-Neptunian Objects and Planet 9: The Observatory will conduct searches for outer solar system objects, striving to detect or rule out significant portions of the phase space in existing Planet 9 hypotheses.
5. Transient Universe: The latency and cadence of SO observations will allow insights into the transient universe over a range of temporal scales, complementing data from facilities such as the Vera C. Rubin Observatory.
6. Polarized Galactic Emission: SO seeks to investigate the properties of dust and the influence of magnetic fields in star formation processes within our galaxy.

Strong Numerical Results

• The LAT is expected to survey approximately 61% of the sky, with a map depth reaching 2.6 $\upmu$K⋅arcmin, significantly enhancing data available from current surveys.
• It is forecasted to compile a catalog of over 30,000 galaxy clusters and more than 100,000 extragalactic sources, a notable increment over prior datasets.

Implications and Future Prospects

The implications of these advancements manifest both theoretically and practically. Theoretically, the data will refine models of early universe conditions, dark energy effects, and large-scale structures. Practically, astronomical object catalogs from SO will serve as benchmarks for observational cosmology and cross-disciplinary research. Further, advanced sky surveys foster collaborative opportunities with upcoming missions and enhance complementary data analyses in the astronomical community.

On a speculative note, future directions might include the integration of artificial intelligence techniques to handle the substantial data outputs, automating data classification, analysis, and possibly predicting astrophysical phenomena. The expansion of exploration capabilities could uncover new phenomena, potentially reshaping our understanding of the universe.

In sum, the paper portrays the Simons Observatory as a significant contributor to our cosmic understanding, with planned advancements promising substantial impacts across several domains of astrophysics and cosmology, thus setting a cornerstone for the observational priorities and technologies of the coming decades.