During the last decades, high-precision experiments have made increasingly detailed measurements of diffuse Extragalactic Background Light (EBL) emitted by cosmological sources. This has revolutionized the understanding of our cosmic origins. The Cosmic Microwave Background (CMB) is our most precious resource for understanding the Big Bang, while the Cosmic Infrared and Optical Backgrounds (CIB and COB) provide unique constraints on the evolution of large scale structure from the first galaxies to today. Until recently, measurements of these effects were limited by either foregrounds or instrumental noise. However, the combined signal-to-noise ratio has now grown so large that the interplay between astrophysical confusion and instrumental systematic uncertainties dominate the error budget. To make further process, it has become critical to account for all sources of uncertainties simultaneously. Origins project aims at solving this challenge through joint integrated end-to-end analysis of multiple state- of-the-art experiments to construct a single coherent model of all main diffuse astrophysical emission processes from 1𝜇m to 23GHz.
In a novel approach, Origins will utilize archival observations from ACT, AKARI, COBE/DIRBE, COBE/FIRAS, IRAS, Planck, and WMAP, many in the form of raw time-ordered data, with upcoming measurements from Simons Observatory and SPHEREx. This will result in the world’s strongest and most robust constraints on primordial inflationary gravitational waves; the most accurate map of CIB fluctuations published to date; and possibly the world’s first map of large-scale COB fluctuations.
Simultaneously, it will redefine our understanding of thermal dust emission in the Milky Way spanning a wide range of the electromagnetic spectrum, and will improve the precision of current models of Zodiacal Light by several orders of magnitude. This Open Science project will define a new paradigm for next-generation CMB 𝐵-mode and EBL experiments.
Scientific objectives
1) World-leading constraints on inflation. Working as part of the SO LAT and SAT foreground removal working groups, Origins will use SO maps along with satellite data to create the highest sensitivity multi-experiment 𝐵-mode maps published to date, and use these to constrain primordial gravitational waves. This will either result in the world’s first detection of Primordial Gravitational Waves, or rule out large classes of inflationary models.
2) Constraints on galaxy and star formation from high-resolution multi-wavelength CIB/COB maps. By combining Planck, DIRBE, IRAS, Akari, and SPHEREx data, this project will produce a ground breaking high-sensitivity, arcmin resolution, and low-systematics CIB map, and use this both to constrain early galaxy formation and as 3D tracer for 𝐵-mode delensing. In addition, we are already on the brink of detecting the COB in DIRBE, and with SPHEREx we will revolutionize this field. As a high risk/high gain effort, we will also attempt to perform true 3D tomography of the cosmological density field by fitting CIB and COB in redshift slices, a method that was explored by Planck, but never brought to full fruition.
3) A precise 3D interplanetary dust model. By combining low-level DIRBE, IRAS, Akari, and SPHEREx data, Origins will make a ground-breaking model of zodiacal emission, using both parametric and non-parametric models to constraining the rich 3D and time-variable structure of the IPD. This framework will be the first joint-experiment analysis of interplanetary dust to combine data from different epochs and vantage points, allowing for a unprecedented 3D probe of the interplanetary dust distribution.
4) The most complete data-driven foreground emission model available. I will combine state-of-the-art microwave survey data (WMAP, Planck, ACT, and FIRAS) with the best full-sky infrared survey data available (IRAS, DIRBE, Akari, and SPHEREx) to create the most accurate parametric model of the radio, microwave, and sub-mm sky published to date.
5) A fully Open Science framework and community. I will make the reprocessed low-level data and high- level science products publicly available, as far as permitted by individual consortium policies, together with all codes required to generate these outputs. I will also train the next generation of young scientists in using and improving these results further, and build an entire community around these groundbreaking ideas.
