UC Berkeley Astronomers Witness Magnetar Birth in Superluminous Supernova, Detect First “Chirp” from General Relativity
UC Berkeley astronomers and collaborators observed the birth of a magnetar inside superluminous supernova SN 2024afav, confirming magnetar-powered SLSNe and detecting a novel relativistic “chirp” in the light curve, reported in Nature.
Key takeaways
- Magnetar birth observed: Newborn magnetar identified inside SN 2024afav.
- Relativistic “chirp” detected: A repeating brightening pattern in the light curve (repeating “chirp”) matches magnetar models shaped by general relativity.
- Magnetar parameters measured: Spin ~4.2 ms and magnetic field ~3×10^14 gauss (roughly 300 trillion times Earth’s field).
- Distance and publication: The explosion occurred about one billion light-years from Earth; results published in Nature, validating a model proposed by Dan Kasen in 2010 (UC Berkeley L&S).
Main content
How the team saw the magnetar birth
SN 2024afav first brightened in December 2024. Over months of monitoring, the team recorded small periodic bumps — a clear, repeating “chirp” in the light curve. That signature matched predictions that a newborn, fast-spinning magnetar injects pulsed energy into expanding debris (Berkeley news; UC Berkeley L&S).
Lead analyst Joseph Farah (graduate student, UC Santa Barbara; incoming Miller Postdoctoral Fellow at UC Berkeley) led the light-curve analysis. Farah described the signal as “unmistakable”, noting that the pattern fits a magnetar powering the sustained glow (Berkeley news; NationalToday).
What a magnetar is and why it matters
A magnetar is an ultra-dense neutron star roughly 10 miles across. When a massive star’s core collapses, a compact remnant can retain enormous spin and trap a magnetic field so intense that young magnetars can rotate >1,000 times per second and have fields 100–1,000× stronger than ordinary pulsars (UC Berkeley L&S).
Those spins and fields act as engines: the rotating magnetic field accelerates charged particles that slam into the supernova debris, injecting energy that keeps the explosion bright for months — the defining trait of Type I superluminous supernovae (SLSNe-I) (Berkeley news; PopSci).
The “chirp” and general relativity
The repeating brightening — called a “chirp” — arises from the interplay between the magnetar’s spin, pulsed energy injection, and the expanding shell of debris, shaped by relativistic effects. Relativity changes how the pulsed emission is beamed and time-delayed as the ejecta expand, producing a time-evolving pattern that is now observable. This is the first detection of such a relativistic chirp in a supernova (NationalToday; Berkeley news).
Alex Filippenko, UC Berkeley professor and co-author: “To see a clear effect of Einstein’s general theory of relativity is always exciting, but seeing it for the first time in a supernova is especially rewarding.”
Background: theory and earlier work
SLSNe were first recognized in the early 2000s; their brightness and longevity exceeded iron-core collapse models. In 2010, Dan Kasen (UC Berkeley) and collaborators proposed that magnetars could power long-lived SLSNe. The new Nature paper (11 March 2026) provides direct observational support for that model (UC Berkeley L&S).
The result ties together decades of theory and complementary work by other researchers such as Stanford Woosley (UC Santa Cruz), linking theoretical predictions to clear observational evidence (Berkeley news).
Team, tools and support
The collaboration includes Joseph Farah (lead analyst, LCO/UC Santa Barbara), Alex Filippenko (UC Berkeley), D. Andrew Howell (LCO/UCSB), Logan Prust (Flatiron Institute), Yuan Qi Ni (UCSB), and others (UC Berkeley L&S; Berkeley news).
Funding and philanthropic gifts supported observations and analysis, including donors who sustain long-term programs and help maintain rapid response capabilities for transient discovery; the team acknowledges contributors such as Christopher R. Redlich among others (Berkeley news).
Broader context and related phenomena
Magnetars are also leading candidates for the sources of some fast radio bursts (FRBs). Directly identifying a magnetar inside an SLSN-I helps connect explosive stellar death, extreme magnetic physics, and transient radio phenomena, offering a multi-messenger template for future searches (UC Berkeley L&S; Smithsonian Magazine).
By searching for similar chirps in archival and new SLSNe-I, astronomers can build a sample of magnetar births, measure spin and field distributions, and refine stellar-death models (NationalToday; ScienceSprings).
Implications for the United States of America
Economic impact: The discovery highlights U.S. leadership in astronomy and underscores the value of continued investment in observatories, data infrastructure, and research grants, which yield technology transfers and workforce development (Berkeley news).
Political consequences: Results like this can support arguments for robust federal funding of basic research (NASA, NSF) and bipartisan backing of science infrastructure (UC Berkeley L&S).
Social and cultural effects: High-profile discoveries boost public interest in STEM, strengthen outreach and education pipelines, and spotlight public universities’ role in national scientific leadership (Smithsonian Magazine).
Practical applications: While basic in nature, the observational techniques and data-analysis methods often transfer to optics, sensors, computing, and pattern-detection algorithms used across industry (PopSci).
Next steps in research
The team will comb archival surveys and monitor new SLSNe-I for similar chirps to expand the magnetar-birth sample, test the prevalence of magnetar-powered explosions, refine progenitor and engine models, and probe links to FRBs when timing and environments align (NationalToday; Berkeley news).
Selected quotes from the team
- Joseph Farah: “This is the most exciting thing I have ever had the privilege to be a part of… It’s the universe telling us out loud and in our face that we don’t fully understand it yet.” (Berkeley news; NationalToday).
- Alex Filippenko: “To see a clear effect of Einstein’s general theory of relativity is always exciting, but seeing it for the first time in a supernova is especially rewarding.” (NationalToday).
- D. Andrew Howell: “Joseph has found the smoking gun… explained everything with… general relativity. It is incredibly elegant.” (Berkeley news).
Sources and further reading
- UC Berkeley news release
- UC Berkeley College of Letters & Science summary
- Smithsonian Magazine summary
- PopSci coverage
- NationalToday report
- ScienceSprings repost
Reporters: Times Media Service
