The Zwicky Transient Facility observed over 3,500 “standard candle” supernova explosions

The Zwicky Transient Facility (ZTF) collaboration has announced a major milestone in the study of cosmic expansion and supernova physics with the release of over 20 scientific publications in a special issue of the journal Astronomy and Astrophysics.

Locations of the 3628 Type Ia supernova explosions in distant galaxies observed with the Zwicky Transient Facility (ZTF) at Palomar Observatory in California. The 1.2-meter telescope scanned the Northern sky not blocked by our own Milky Way (dark region) during three years to collect this data. The insets show one particular example of a Type Ia SN discovered by ZTF, indicating the evolution from right before the explosion, and the two following months.
Figure credit: Mickael Rigault.

Researchers at The Oskar Klein Centre, Stockholm University have played a leading role when ZTF publishes a comprehensive suite of over 20 scientific publications in a special issue of the journal Astronomy and Astrophysics. These studies are based on an unprecedented sample of 3,628 Type Ia supernovae, shedding new light on the nature of these stellar explosions and their role in measuring the expansion history of the universe.

Type Ia supernovae serve as crucial cosmic distance markers, allowing astronomers to trace the accelerated expansion of the universe driven by dark energy. The extensive dataset provided by ZTF, a leading time-domain survey based at the Palomar Observatory, represents the largest and most systematically analyzed nearby sample of Type Ia supernovae (SNIa) to date. This dataset enables a deeper understanding of supernova properties, explosion mechanisms, and their potential systematic effects on cosmological measurements.

Ariel Goobar.
Photo: Adam af Ekenstam

Professor Ariel Goobar, leading the supernova cosmology team at the Oskar Klein Centre, Stockholm University, one of the founding institutions of ZTF, and also member of the research group that discovered the accelerated expansion of the Universe in 1998 stresses the importance of the new data release: “the aim is to address one of our time’s biggest question in fundamental physics and cosmology, namely what is most of the Universe made of? To answer that, the ZTF supernova data is essential.”

Major leap in supernova cosmology

“Our analysis presents a major leap in the precision and scope of supernova cosmology,” says Joel Johansson, a researcher at the Department of Physics, Stockholm University and at OKC. “The breadth and uniformity of the ZTF sample allow us to refine our understanding of these cosmic beacons and improve their use as standard candles for measuring the expansion of the universe.”

The suite of publications covers a range of topics, including refinements to supernova classification, improved light curve modeling techniques, new constraints on progenitor systems, and studies of the environments where these explosions occur. Key results include a novel way to describe the energy output of these powerful explosions, spearheaded by Oskar Klein Centre postdoc D’Arcy Kenworthy.

ZTF’s continuous monitoring of the night sky and its rapid detection and classification capabilities have been instrumental in assembling this vast dataset. Professor Jesper Sollerman, also at OKC and the Department of Astronomy, Stockholm University, has played a leading role in the systematic classification of stellar explosions with ZTF.

Global effort to understand the transient universe

The program operates in coordination with many observatories, including the Nordic Optical Telescope, contributing to a global effort to understand the transient universe. The findings from these studies set the stage for future advancements in time-domain astronomy, particularly with upcoming surveys such as the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST). The lessons learned from ZTF’s Type Ia supernova sample will help refine the methods used in next-generation cosmological surveys.

For more information on the international research team, the published studies and the underlying dataset, see links below:

Articles on Astronomy and Astrophysics website
Astronomy and Astrophysics press-release and data access

Media contact:
Ariel Goobar,
Professor at The Oskar Klein Centre, Department of Physics, Stockholm University
ariel@fysik.su.se

Theme

Research subjects

Cosmology, Particle Astrophysics and Strings Supernovae

Research project

Spectral modelling of supernova and kilonova explosions:

diagnosing the element factories of the Universe

Research groups

The supernova group

Massive stars can end their lives in giant explosions, so-called supernovae.

Cosmology

Cosmology observation and instrumentation work at the department includes supernovae, the cosmic microwave background, and large surveyes of galaxies.

Last updated: February 14, 2025

Source: Communications Office

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