The Dark Energy Survey (DES) collaboration, that includes UCL researchers, has achieved one of the most solid measurements, of constraints on the universe’s expansion till date. The international group of researchers, which was led, by the U.S. Department of Energy’s Fermi National Accelerator Laboratory (Fermilab), analyzed like nearly 1,500 supernovae using machine learning techniques.
The culmination of more than two decades’ work, the findings have provided pivotal new support for the standard model of a universe with an accelerated expansion and marks similar to a significant advancement in our knowledge of the universe.
In 1998, astrophysicists discovered that the cosmos is expanding at a rate that is accelerating, which is attributed to a mysterious entity, that is known as dark energy, and it now makes up roughly 70% of our cosmos. This discovery was achieved by observing exploding stars called supernovae of type la, which are really constant for scientists because they all have approximately the same brightness, which is intriguing.
The DES collaboration has now modified this similar technique for its most recent study, which is the last study of the DES Supernova Working Group, in order to delve deeper than ever into the secrets of dark energy and the universe’s expansion.
A Quantum Leap with Machine Learning and Supernovae- Dark Energy Analysis:
The DES cooperation, which started in 2012, has used a specially designed “Dark Energy Camera” at the US National Science Foundation’s Cerro Tololo Inter-American Observatory in Chile to map nearly one-eighth of the sky. The 570-megapixel digital camera comprises five precisely shaped lenses, the largest nearly a yard across, designed and fabricated at UCL.
DES scientists analyzed data using a range of techniques, for instance, comparing the brightness of type la supernovae to determine how quickly they seem to be moving away from Earth due to like, the effects of da’k energy and the cosmos that expanding. In doing this they have been able to deduce that the overall density of da’k energy in the cosmos is likely constant. This provides, some of the strongest support yet, for the current understanding of the evolution of the universe although; does not rule out the possibility of something even more complex.
Probing the Universe: Insights from Supernovae and Dark Energy:
Professor Ofer Lahav (UCL Physics & Astronomy), who over many years has coordinated the DES Science program and the DES:UK consortium, says, “Congratulations to the DES supernovae team on this remarkable measurement of dark energy and dark matter properties; from this large sample of over 1,500 supernovae, classified by advanced AI methods”.
It has taken more than 20 years to build DES research and instrumentation, involving hundreds of international partners, including UK universities. Under the sponsorship of STFC, UCL has built the analysis infrastructure and the DES optical corrector.
“These new supernovae results have wonderfully proven that the expansion of the cosmos is speeding, most likely as a result of a cosmological constant, or some variation thereof, which was proposed by Einstein in 1917. This finding opens the door to further ambitious initiatives to better understand the nature of da’k energy and dark matter, in which UCL is significantly involved. Examples of these initiatives are the Dark Energy Spectroscopic Instrument (DESI), the Rubin Observatory LSST project, and the space telescope Euclid.
Dr. Paul Shah, an Honorary Research Fellow at UCL Physics & Astronomy who participated in the investigation, stated: “We can see back nearly eight billion years into the past of our expanding cosmos thanks to the DES supernovae.” What is da’k energy is the main question we aim to address. What did it originate from and what will it do going forward? Based on these DES discoveries, da’k energy will remain the dominant component of our cosmos for a very long time, even if it does change over time—but it will do so very slowly.”
The cosmological analysis of the DES Supernova sample was co-led by Boston University Professor Dillon Brout, who stated: “This new supernova result is exciting because it means we can really tie a bow on it and hand it out to the community and say, this is our best attempt at explaining how the universe is working.” For a considerable amount of time to come, these constraints will serve as a gold-standard in supernova cosmology.
The Path Forward: A Global Collaboration:
More than 400 astrophysicists, astronomers, and cosmologists from over 25 universities—including UCL—as well as the Universities of Manchester, Nottingham, Portsmouth, Southampton, and Sussex—are involved in the international Dark Energy Survey project. Since the project’s inception in 2004, the UK has participated internationally, with funds provided by the STFC for the largest-ever galaxy survey on behalf of the UK.
The results were presented at the 243rd meeting of the American Astronomical Society on January 8 and in a publication entitled “The Dark Energy Survey: Cosmology results with ~1500 new high-redshift type la supernovae using the full 5-year dataset” that was submitted to the Astrophysical Journal in January.