During the last few decades, cosmology has transitioned from being data-starved and prone to speculation into a high-precision science that is able to answer fundamental questions regarding the history and nature of the Universe with percentage accuracy. This transformation has been driven by a host of different experiments, each providing a unique and valuable piece of the full puzzle, often at the cost of tens or hundreds of millions of dollars and euros.
Today, the sensitivity of these data sets and experiments has become so large that raw noise is no longer the main obstacle to making new discoveries, but rather degeneracies from foreground confusion and systematic errors. To break through these challenges, it is therefore no longer sufficient to build and analyse a given experiment in isolation, but it is instead critically important to exploit
information from all available complementary experiments at the same time. As a concrete and important example, ESA's Planck mission measured the microwave sky with unprecedented precision at nine frequencies between 30 and 857 GHz, and these measurements will serve as a bedrock for all future cosmology experiments, including Euclid, SKA, LiteBIRD, PICO and others.
Cosmoglobe is a ground-breaking response to these challenges, as it aims to establish a common Open Science and community-driven platform for jointly analyzing legacy, current and future experiments. As such, Cosmoglobe is several things at once: It is a computational computer code that is able to analyze different experiments jointly; it is a detailed model of the astrophysical sky at radio, microwave, and submillimeter wavelengths; and it is an Open Science collaboration of individual scientists and experiments all working together towards the common goal of understand the properties of our universe.
The Cosmoglobe project has been extremely successful, and a few selected highlights include the following:
1) We have reanalyzed the Planck LFI and WMAP data jointly within a ground-breaking end-to-end Bayesian analysis framework. This analysis represents the first real-world demonstration of the Cosmoglobe framework, and it has resulted in new state-of-the-art maps for both experiments with unprecedently low levels of systematic errors.
2) We have successfully extended and applied the same framework to the COBE-DIRBE data, and derived a new state-of-the-art zodiacal light model, a new multi-component thermal dust model for the Milky Way, and constrained the CIB monopole directly with DIRBE frequency maps. While the original DIRBE maps were strongly contaminated by zodiacal light, which prevented them from detecting the CIB signal, the new analysis finally achieves the original science goal of the DIRBE experiment.
3) We have implemented an end-to-end analysis pipeline for carbon-monoxide intensity mapping measurements as produced by the COMAP instrument, and applied this to its first three years of data. The results from this are summarized in two paper suites comprising 7 and 4 papers, respectively. The second season results provide the strongest constraints on clustered cosmological CO structure published to date, and the upper limits are close to those predicted by a wide range of theoretical models. With a few more years of data in hand, a first detection may be nearby.
As of today, the Cosmoglobe community is rapidly growing, and new experiments, groups and scientists are coming aboard regularly. The future of Cosmoglobe looks very bright.
