Answering fundamental questions about the early universe
Humans have questioned the origins of our universe for thousands of years. Observations over the past couple of decades have started to piece together this complex and fundamental puzzle. Yet, with each new piece, more questions follow. The standard model of Big Bang cosmology describes how the early universe began nearly 14 billion years ago, and (from the earliest moment) grew through a period of exponential, accelerated expansion known as inflation. Over the next few billion years, large-scale structures such as clusters and galaxies gradually emerged. They were shaped by the gravitational instability of dark matter, a hypothetical cosmic ingredient which only reacts with standard matter through gravity.
Understanding the nature of dark matter
A few billion years ago, we entered another phase of expansion, driven by dark energy – an enigmatic and invisible form of energy. Uncovering the truth of such dark entities could help to answer some of the fundamental questions about the history of our universe. The PiCOGAMBAS project, an international effort from scientists at Cardiff University(opens in new window) in the United Kingdom and the Simons Foundation(opens in new window) in the U.S. sought to glean new insights into the nature of inflation, dark energy and dark matter. One source of answers comes in the form of cosmic microwave background (CMB), which is relic ‘light’ from the Big Bang. This light – which we see as electromagnetic microwave radiation – passes through large cosmic structures on its journey towards us, leaving distinct imprints in CMB photons. The PiCOGAMBAS project was funded by the Marie Skłodowska-Curie Actions(opens in new window) program.
Combining U.S. and EU space expertise
The project harnessed new datasets available from partner institutions in Europe and the U.S. including a new generation of CMB experiments from the Simons Observatory and galaxy surveys from European Space Agency(opens in new window) missions such as Euclid and Gaia. It was this unique combination of expertise that enabled researchers to devise new methods to examine data from observations of the CMB, and cross-correlate this with existing galaxy surveys. This allowed the team to study properties of the matter distributed through the universe and how it evolved. The work included designing and combining numerical simulations, statistical techniques and new forms of data analysis. This helped the transatlantic team to analyze the CMB and better understand how gravitational lensing of the microwave background radiation occurred.
Ongoing collaborative work
Precise measurements pioneered by the Simons Foundation, combined with optical data from the ESA Gaia mission, helped the researchers to probe the expansion history of the universe and dig deeper into the properties of dark matter. One major outcome of this collaborative work has been the analysis of so-called B-modes, i.e. polarized CMB radiation. The team found that observing B-modes can help us understand how perturbations in dark matter distribution happened in the period of cosmological inflation. This is key, as these are the fluctuations that led to the formation of large universal structures. Findings from the project have demonstrated that cosmological data from the CMB appears to be consistent throughout the entire history of the universe, with new methods allowing researchers to study models of dark matter, dark energy and inflation. The team hopes that ongoing collaborative work will continue to advance our knowledge of the early universe.