A massive dataset of 3,628 Type Ia Supernovae from the Zwicky Transient Facility is being released, offering new insights into cosmic expansion.
This unprecedented collection will refine how cosmologists measure distances and study dark energy. With high-precision data from cutting-edge telescopes, scientists aim to resolve discrepancies in the standard cosmological model and explore new physics.
A Game-Changing Dataset for Cosmology
A groundbreaking dataset of Type Ia supernovae, released on February 14, could transform how cosmologists measure the expansion history of the universe.
Dr. Mathew Smith and Dr. Georgios Dimitriadis from Lancaster University are members of the Zwicky Transient Facility (ZTF), a wide-field astronomical survey that uses an advanced camera on the Samuel Oschin Telescope at Palomar Observatory in California.
Type Ia supernovae are powerful explosions that mark the end of a white dwarf star’s life. Because their brightness is consistent, scientists use them as cosmic mile markers — measuring their light to determine distances across the universe.
A Historic Data Release
On February 14,, the ZTF cosmology science working group published 21 studies on 3,628 Type Ia supernovae, featured in a special issue of Astronomy & Astrophysics.
Lancaster astrophysicist Dr. Mathew Smith, co-leader of the ZTF SN Ia DR2 release, said: “This release provides a game-changing dataset for supernova cosmology. It opens the door to new discoveries about both the expansion of the universe and the fundamental physics of supernovae.”
The Scale of the ZTF Breakthrough
This is the first time that astrophysicists have access to such a large and homogeneous dataset. Type Ia supernovae are rare, occurring approximately once per thousand years in a typical galaxy, but ZTF’s depth and survey strategy enable researchers to detect nearly four per night. In only two and a half years, ZTF has doubled the number available Type Ia Supernovae for cosmology acquired for the last 30 years to almost three thousand.
Head of the ZTF Cosmology Science working group Dr. Mickael Rigault from the Institut des deux Infinis de Lyon (CNRS / Claude Bernard University) said: “For the past five years, a group of thirty experts from around the world have collected, compiled, assembled, and analyzed these data. We are now releasing it to the entire community. This sample is so unique in terms of size and homogeneity, that we expect it to significantly impact the field of Supernovae cosmology and to lead to many additional new discoveries in addition to results we have already published.”
The Cutting-Edge Technology Behind ZTF
The ZTF camera, installed on the 48-inch Schmidt telescope at Palomar Observatory, scans the entire northern sky daily in three optical bands, reaching a depth of 20.5 magnitude—one million times fainter than the dimmest stars visible to the naked eye. This sensitivity allows ZTF to detect nearly all supernovae within 1.5 billion light-years of Earth.
Capturing Supernovae in Real Time
Professor Kate Maguire from Trinity College Dublin, a co-author of the study, said: “Thanks to ZTF’s unique ability to scan the sky rapidly and deeply, we have captured multiple supernovae within days—or even hours—of explosion, providing novel constraints on how they end their lives.”
The acceleration of the expansion of the Universe, awarded by the Nobel prize in 2011, was discovered in the late 90s using approximately a hundred of these supernovae. Since then, cosmologists have been investigating the reason for this acceleration caused by the dark energy that plays the role of an anti-gravity force across the Universe.
Answering the Universe’s Biggest Questions
Co-author Professor Ariel Goobar, Director of the Oskar Klein Centre in Stockholm, one of the founding institutions of ZTF, and also member of the team that discovered the accelerated expansion of the Universe in 1998 said: “Ultimately, the aim is to address one of our time’s biggest questions in fundamental physics and cosmology, namely what is most of the Universe made of? For that, we need the ZTF supernova data.”
One of the key outcomes of these studies is that Type Ia Supernovae intrinsically vary as a function of their host environment, more so than expected before, and the correction mechanism assumed so far has to be revisited. This could change how we measure the expansion history of the Universe and may have important consequences for the current deviations observed in the standard model of cosmology.
The Path Forward for Supernova Cosmology
Dr. Rigault said: “With this large and homogeneous dataset, we can explore Type Ia supernovae with an unprecedented level of precision and accuracy. This is a crucial step toward honing the use of Type Ia Supernovae in cosmology and assessing if current deviations in cosmology are due to new fundamental physics or unknown problems in the way we derive distances.”
Reference: “ZTF SN Ia DR2: Overview” by M. Rigault, M. Smith, A. Goobar, K. Maguire, G. Dimitriadis, J. Johansson, J. Nordin, U. Burgaz, S. Dhawan, J. Sollerman, N. Regnault, M. Kowalski, P. Nugent, I. Andreoni, M. Amenouche, M. Aubert, C. Barjou-Delayre, J. Bautista, E. Bellm, M. Betoule, J. S. Bloom, B. Carreres, T. X. Chen, Y. Copin, M. Deckers, T. de Jaeger, F. Feinstein, D. Fouchez, C. Fremling, L. Galbany, M. Ginolin, M. Graham, S. L. Groom, L. Harvey, M. M. Kasliwal, W. D. Kenworthy, Y.-L. Kim, D. Kuhn, S. R. Kulkarni, L. Lacroix, R. R. Laher, F. J. Masci, T. E. Müller-Bravo, A. Miller, M. Osman, D. Perley, B. Popovic, J. Purdum, Y.-J. Qin, B. Racine, S. Reusch, R. Riddle, P. Rosnet, D. Rosselli, F. Ruppin, R. Senzel, B. Rusholme, T. Schweyer, J. H. Terwel, A. Townsend, A. Tzanidakis, A. Wold and L. Yan, 14 February 2025, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/202450388
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