Cosmic Eruption Caught in the Act by Submillimeter Array’s New Fastest Response System

An artist's impression of a superluminous supernova and an associated gamma-ray burst being driven by a rapidly spinning neutron star.

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New semi-automated system demonstrates how the radio interferometer quickly responds to discoveries from space-based telescopes

Cambridge, MA (June 30, 2026) — On January 26, 2026, the Submillimeter Array (SMA) on Maunakea crossed an important threshold for time‑domain astronomy.

For the first time, scientists from the Center for Astrophysics | Harvard & Smithsonian (CfA) demonstrated a new rapid‑response capability at millimeter and submillimeter wavelengths, zooming in on a gamma‑ray burst (GRB) within minutes of its discovery and capturing the earliest observations of such an event ever made at these frequencies.

GRBs are the brightest explosions in the universe — brief but staggeringly immense flashes produced by jets launched in the collapse of massive stars or the merger of compact objects like neutron stars. Their initial burst is followed by a glow that X-ray and optical telescopes have long been able to chase within seconds or minutes of the event, but that millimeter-wave telescopes have historically lagged behind in observing.

That changed in January of this year, when the SMA rapidly responded to an automated alert from NASA’s Neil Gehrels Swift Observatory, which detected a flash of gamma rays. The sequence played out almost entirely without human intervention. Within 90 seconds, the on-duty operator had been alerted. Within four minutes, the telescope was moving to start observations.

"It was an incredible thing to watch in real time," said Garrett Keating, an astrophysicist at CfA and Deputy Director of the SMA, who led the rapid-response effort. "Being able to react and process data this quickly is a big departure from how SMA usually operates, but it was absolutely critical for capturing an event where minutes matter. This was the first time we had the full system online. We learned a lot from the experience, and think we can get the response time down to as little as two to three minutes."

Within thirteen minutes, the telescopes were on target, and a separate automated analysis was already generating images of the explosion in near real-time.

“With interferometry, we don’t get direct images from the telescope,” explained Ranjani Srinavasan, interim director of the SMA. “Usually that process takes a long time.”

The response time is roughly two orders of magnitude faster than the typical response time for millimeter and submillimeter telescopes.

“The SMA’s new capability is a game-changer for the field,” said Edo Berger, professor of astronomy at Harvard and a co-author of the study.

Follow‑up observations two days later showed that the source had faded, strengthening the case that SMA had indeed captured a transient afterglow rather than a steady background galaxy.

“This new capability opens a unique window into the physics behind some of the most powerful stellar explosions,” said Tanmoy Laskar, Assistant Professor of Physics and Astronomy at the University of Utah and a coauthor of the study. “With the SMA, we can now probe the structure and composition of the ejecta in unprecedented detail, bringing us closer to understanding how these explosions launch their powerful jets.”

The fast observations mark the launch of the SMA Sub/millimeter Program to Rapidly Investigate Novel Time‑domain Sources (SMA SPRINTS), a program designed to use the SMA and its wideband upgrade, called wSMA, to provide quick, sensitive and flexible follow‑up of transient events across the time‑variable sky.

The goal is to be ready as new facilities such as the Rubin Observatory’s Legacy Survey of Space and Time (LSST) and, later, the Roman Space Telescope, begin sending large numbers of alerts to the astronomy community.

The successful demonstration is published today in Astrophysical Journal Letters. Co-authors include Peter Blanchard, Mark Gurwell, Joshua Lovell, Ramprasad Rao, and Peter Willians, all from CfA, Anna Ho from Cornell University, Kate Alexander from the University of Arizona, Tarraneh Eftekhari from Northwestern University, and Chloe Xu from the Massachusetts Institute of Technology.

Source: Harvard-Smithsonian Center for Astrophysics (CfA)/News

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About the Center for Astrophysics | Harvard & Smithsonian

The Center for Astrophysics | Harvard & Smithsonian is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory designed to ask, and ultimately answer, humanity’s greatest unresolved questions about the universe.

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Measuring the expansion of the universe with cosmic fireworks

High-resolution image taken with the Large Binocular Telescope on Mount Graham in Arizona, USA, displaying the two lens galaxies in a warm tone, and the five lensed copies of SN Winny in blue. © Credit: SN Winny Research Group

Munich astronomers image and model extremely rare gravitationally lensed supernova

That the universe is expanding has been known for almost a hundred years now, but how fast? The exact rate of that expansion remains hotly debated, even challenging the standard model of cosmology. A research team at the Technical University of Munich (TUM), the Ludwig Maximilians University (LMU) as well as the Max Planck Institutes for Astrophysics (MPA) and Extraterrestrial Physics (MPE) has now imaged and modelled an exceptionally rare supernova that could provide a new, independent way to measure how fast the universe is expanding.

• An image that could solve a long lasting cosmic mystery


• Unprecedented chance to measure the growth of the universe


• Collaboration between TUM, LMU and Max Planck Institutes

The supernova is a rare superluminous stellar explosion, 10 billion lightyears away, and far brighter than typical supernovae. It is also special in another way: the single supernova appears five times in the night sky, like cosmic fireworks, due to a phenomenon known as gravitational lensing. Two foreground galaxies bend the supernova’s light as it travels toward Earth, forcing it to take different paths. Because these paths have slightly different lengths, the light arrives at different times. By measuring the time delays between the multiple copies of the supernova, researchers can determine the universe’s present-day expansion rate, known as the Hubble constant.

Sherry Suyu, Associate Professor of Observational Cosmology at TUM and Fellow at the Max Planck Institute for Astrophysics, explains: “We nicknamed this supernova SN Winny, inspired by its official designation SN 2025wny. It is an extremely rare event that could play a key role in improving our understanding of the cosmos. The chance of finding a superluminous supernova perfectly aligned with a suitable gravitational lens is lower than one in a million. We spent six years searching for such an event by compiling a list of promising gravitational lenses, and in August 2025, SN Winny matched exactly with one of them.”

Large Binocular Telescope auf dem Mount Graham in Arizona, USA
© Credit: Dr. Christoph Saulder / MPE

High-resolution color image of unique supernova

Because gravitationally lensed supernovae are so rare, only a handful of such measurements have been attempted to date. Their accuracy depends strongly on how well one can determine the masses of the galaxies acting as a lens, because these masses control how strongly the supernova’s light is bent. To measure those masses, the team obtained images with the Large Binocular Telescope in Arizona, USA, using its two 8.4-meter diameter mirrors and an adaptive optics system that corrects for atmospheric blurring. The result is the first high-resolution color image of this system published to date.

The observations reveal the two foreground lens galaxies in the center and five bluish copies of the supernova - reminiscent of a firework exploding. This comes as a surprise, since galaxy-scale lens systems normally produce only two or four copies. Using the positions of all five copies, Allan Schweinfurth and Leon Ecker, junior researchers in the team, built the first model of the lens mass distribution.

“Until now, most lensed supernovae were magnified by massive galaxy clusters, whose mass distributions are complex and hard to model,“ says Allan Schweinfurth. “SN Winny, however, is lensed by just two individual galaxies. We find overall smooth and regular light and mass distributions for these galaxies, suggesting that they have not yet collided in the past despite their close apparent proximity. The overall simplicity of the system offers an exciting opportunity to measure the universe’s expansion rate with high accuracy.”

Members of the SN Winny Research Group at Research Campus Garching (from left): Stefan Taubenberger, Allan Schweinfurth, Alejandra Melo, Elias Mamuzic, Sherry Suyu, Christoph Saulder, Roberto Saglia, Leon Ecker, Limeng Deng. © Credit: Dr. Robert Reich / TUM

Two methods, two very different results

So far, scientists have mostly relied on two methods to measure the Hubble constant, but these methods yield conflicting results. This puzzle is known as the Hubble tension.

The first is the local method, which measures distances to galaxies one step at a time, much like climbing a ladder, where each step depends on the previous one; hence, it is referred to as the cosmic distance ladder. It uses objects with well-known brightness to estimate distances and then compares those distances with how fast galaxies are moving away. Because this method involves many calibration steps, even small errors can accumulate and affect the final result.

The second method looks much farther back in time. It studies the cosmic microwave background, the faint afterglow of the Big Bang, and uses models of the early universe to calculate today’s expansion rate. This approach is highly precise, but it relies heavily on assumptions about how the universe evolved, and these assumptions are still subject to debate.

SN Winny
Credit: Elias Mamuzic / MPA / TUM

A new, one-step approach

Animation (available in several languages) showing the gravitational lensing effect of the pair of foreground galaxies on the host galaxy of SN Winny. The host galaxy is lensed into multiple images, which are distorted and stretched out to form a bluish ring around the lens. The explosion of SN Winny itself and the time-delayed arrival of its multiple lensed copies on Earth are also simulated. Ultimately, the animation fades to a real observation of SN Winny, captured at the Large Binocular Telescope in Arizona.

A third, independent method now enters the picture: using a gravitationally lensed supernova. Stefan Taubenberger, a leading member of Professor Suyu’s team and first author of the supernova-identification study, explains that by measuring the time delays between the multiple copies of the supernova and knowing the mass distribution of the lensing galaxy, scientists can directly calculate the Hubble constant: “Unlike the cosmic distance ladder, this is a one-step method, with fewer and completely different sources of systematic uncertainties.”

Astronomers worldwide are currently observing SN Winny in detail using both ground-based and space-based telescopes. Their results will provide crucial new insights and help clarify the long-standing Hubble tension.

Source: Max Planck Institute for Astrophysics/Press Releases

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Contacts:

Prof. Dr. Sherry Suyu
Scientific Staff
Tel: 2015

Stefan Taubenberger
Tel: 2019
tauben@mpa-garching.mpg.de

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Original publication

1. Taubenberger et al.
HOLISMOKES XIX: SN 2025wny at z = 2, the first strongly lensed superluminous supernova
accepted by Astronomy & Astrophysics (A&A), December 2025

Source

2. Ecker, Schweinfurth et al.
HOLISMOKES XX. Lens models of binary lens galaxies with five images of Supernova Winny
submitted to Astronomy & Astrophysics (A&A)

Source

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Astronomers Discover the First Gravitationally Lensed Superluminous Supernova

SN 2025wny

Gravitationally lensed superluminous supernova
An artist’s interpretation of light from a supernova passing through a gravitational lens, reaching Earth at different times.
Credit: Oskar Klein Center, University of Stockholm / Samuel Avraham & Joel Johansson.

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Maunakea, Hawaiʻi – An international team of astronomers using a combination of ground-based telescopes, including the W. M. Keck Observatory on Maunakea, Hawaiʻi Island, has discovered the first-ever spatially resolved, gravitationally lensed superluminous supernova. The object, dubbed SN 2025wny, offers a rare look at a stellar cataclysm from the early Universe and provides a striking confirmation of Einstein’s theory of general relativity.

SN 2025wny lies so far away that its light has traveled 10 billion years to reach Earth; the Universe was just 4 billion years old when the explosion occurred. Normally, a supernova at this distance would be far too faint to detect from the ground. But two foreground galaxies act as a natural gravitational “magnifying glass,” boosting the supernova’s brightness by a factor of 50 and splitting it into distinct, spatially separated images.

“This is nature’s own telescope,” says Joel Johansson, lead author from the Oskar Klein Centre, Stockholm University. “The magnification lets us study a supernova at a distance where detailed observations would otherwise be impossible.”

The study, led by Stockholm University, is published in The Astrophysical Journal Letters.

An artist’s interpretation of light from a supernova passing through a gravitational lens, reaching Earth at different times.
Credit: Oskar Klein Center, University of Stockholm / Samuel Avraham & Joel Johansson.

A new method to probe the expansion of the universe

Because each of the multiple lensed images takes a slightly different path around the intervening galaxies, their arrival times differ. Measuring these time delays provides a powerful, independent method to determine the Hubble constant—the rate at which the Universe is expanding.

A major unsolved problem in modern cosmology is the Hubble tension—the growing mismatch between measurements of the Universe’s expansion rate made from the early Universe versus those made from nearby objects. The disagreement suggests that our current cosmological model may be incomplete. Strongly lensed supernovae like SN 2025wny offer a new, independent way to measure this expansion rate through time-delay differences between the lensed images, helping determine whether the tension reflects new physics or limitations in existing methods.

“A lensed supernova with multiple, well-resolved images provides one of the cleanest ways to measure the expansion rate of the Universe,” says Ariel Goobar of the Oskar Klein Centre. “SN 2025wny is an important step toward resolving one of cosmology’s most significant challenges.”

A surprising and exceptionally hot explosion

Superluminous supernovae are extremely bright, rare explosions. SN 2025wny stands out even in this elite category: its early ultraviolet light, stretched into optical wavelengths by cosmic expansion, revealed an exceptionally hot, brilliant event.

The supernova’s intense brightness illuminated its host galaxy, allowing astronomers to identify narrow absorption lines from elements such as carbon, iron, and silicon. These fingerprints point to a low-metallicity, star-forming dwarf galaxy—exactly the kind of environment thought to produce superluminous supernovae during the Universe’s youth.

How the Discovery Was Made

The discovery relied on a chain of cutting-edge observatories working together on scientific breakthroughs. The Zwicky Transient Facility (ZTF) at Palomar Observatory in California first detected the explosion during its nightly monitoring of the sky. The Nordic Optical Telescope (NOT) on La Palma in the Canary Islands provided early spectroscopy of the transient, Liverpool Telescope (LT) also on La palma provided four separate images of SN 2025wny, and Keck Observatory ultiumately provided the decisive spectra that confirmed both the supernova type and its extreme distance.

Yu-Jing Qin, a postdoctoral researcher at Caltech, led a series of spectroscopic observations using Keck Observatory’s Low Resolution Imaging Spectrometer (LRIS), targeting each of the individual supernova images and the lensing galaxies.

The Keck spectra revealed a forest of narrow absorption lines from the supernova’s host galaxy – the fingerprints of elements such as carbon, iron and silicon – which nailed down the redshift and nature of the event.

“The spectrum taken with LRIS provides the most convincing measurement of its distance/redshift and pinpointed its classification as a superluminous supernova, which is a rare subclass. We were really impressed by the data quality and are pursuing further observations using other Keck instruments,” said Qin.

These rapid-response observations were enabled by Keck Observatory’s Target of Opportunity (ToO) policy, which allows scientists to request immediate access for short-lived cosmic events.

“It’s always exciting to get a request for a very rapid response to a transient event like this,” said John O’Meara, Chief Scientist and Deputy Director for Keck Observatory. “Keck was ready to respond, and we were happy to deliver and participate in this breakthrough.”

What Comes Next?

SN 2025wny demonstrates that strongly lensed supernovae at very high redshifts can be discovered and resolved with today’s surveys—a crucial proof of concept ahead of the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST), which is expected to uncover hundreds more.

Follow-up observations with the Hubble Space Telescope and James Webb Space Telescope are already underway. These data will refine the gravitational lens model, map the multiple images with exceptional precision, and ultimately measure the time delays needed for a new, independent determination of the Hubble constant.

The extraordinary magnification also offers an unprecedented view into how such extreme explosions work and how stars evolved in the early Universe.

Source: W.M. Keck Observatory/Science News

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About LRIS

The Low Resolution Imaging Spectrometer (LRIS) is a very versatile and ultra-sensitive visible-wavelength imager and spectrograph built at the California Institute of Technology by a team led by Prof. Bev Oke and Prof. Judy Cohen and commissioned in 1993. Since then it has seen two major upgrades to further enhance its capabilities: the addition of a second, blue arm optimized for shorter wavelengths of light and the installation of detectors that are much more sensitive at the longest (red) wavelengths. Each arm is optimized for the wavelengths it covers. This large range of wavelength coverage, combined with the instrument’s high sensitivity, allows the study of everything from comets (which have interesting features in the ultraviolet part of the spectrum), to the blue light from star formation, to the red light of very distant objects. LRIS also records the spectra of up to 50 objects simultaneously, especially useful for studies of clusters of galaxies in the most distant reaches, and earliest times, of the universe. LRIS was used in observing distant supernovae by astronomers who received the Nobel Prize in Physics in 2011 for research determining that the universe was speeding up in its expansion.

About W. M. Keck Observatory

The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two 10-meter optical/infrared telescopes atop Maunakea on the Island of Hawaiʻi feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems. Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. For more information, visit: www.keckobservatory.org

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World's First 3D Simulations Reveal the Physics of Superluminous Supernovae

The nebula phase of the magnetar-powered super-luminous supernova from our 3D simulation. At the moment, the supernova ejecta has expanded to a size similar to the solar system. Large scale mixing appears at the outer and inner region of ejecta. The resulting light curves and spectra are sensitive to the mixing that depends on stellar structure and the physical properties of magnetar. (Image by Ken Chen)

For most of the 20th century, astronomers have scoured the skies for supernovae—the explosive deaths of massive stars—and their remnants in search of clues about the progenitor, the mechanisms that caused it to explode, and the heavy elements created in the process. In fact, these events create most of the cosmic elements that go on to form new stars, galaxies, and life.

Because no one can actually see a supernova up close, researchers rely on supercomputer simulations to give them insights into the physics that ignites and drives the event. Now for the first time ever, an international team of astrophysicists simulated the three-dimensional (3D) physics of superluminous supernovae—which are about a hundred times more luminous than typical supernovae. They achieved this milestone using Lawrence Berkeley National Laboratory’s (Berkeley Lab’s) CASTRO code and supercomputers at the National Energy Research Scientific Computing Center (NERSC). A paper describing their work was published in Astrophysical Journal.

Astronomers have found that these superluminous events occur when a magnetar—the rapidly spinning corpse of a massive star whose magnetic field is trillions of times stronger than Earth’s—is in the center of a young supernova. Radiation released by the magnetar is what amplifies the supernova’s luminosity. But to understand how this happens, researchers need multidimensional simulations.

“To do 3D simulations of magnetar-powered superluminous supernovae, you need a lot of supercomputing power and the right code, one that captures the relevant microphysics,” said Ken Chen, lead author of the paper and an astrophysicist at the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Taiwan.

He adds that the numerical simulation required to capture the fluid instabilities of these superluminous events in 3D is very complex and requires a lot of computing power, which is why no one has done it before.

The turbulent core of a magnetar bubble inside the superluminous supernovae. Color coding shows densities. The magnetar is located at the center of this image and two bipolar outflows are emitted from it. The physical size of the outflow is about 10,000 km. (Image by Ken Chen)

Fluid instabilities occur all around us. For instance, if you have a glass of water and put some dye on top, the surface tension of the water will become unstable and the heavier dye will sink to the bottom. Because two fluids are moving past each other, the physics of this instability cannot be captured in one dimension. You need a second or third dimension, perpendicular to height to see all of the instability. At the cosmic scale, fluid instabilities that lead to turbulence and mixing play a critical role in the formation of cosmic objects like galaxies, stars, and supernovae.

“You need to capture physics over a range of scales, from very large to really tiny, in extremely high-resolution to accurately model astrophysical objects like superluminous supernovae. This poses a technical challenge for astrophysicists. We were able to overcome this issue with a new numerical scheme and several million supercomputing hours at NERSC,” said Chen.

For this work, the researchers modeled a supernova remnant approximately 15-billion kilometers wide with a dense 10-kilometer wide magnetar inside. In this system, the simulations show that hydrodynamic instabilities form on two scales in the remnant material. One instability is in the hot bubble energized by the magnetar and the other occurs when the young supernova’s forward shock plows up against ambient gas.

“Both of these fluid instabilities cause more mixing than would normally occur in a typical supernova event, which has significant consequences for the light curves and spectra of superluminous supernovae. None of this would have been captured in a one-dimensional model,” said Chen.

They also found that the magnetar can accelerate calcium and silicon elements that were ejected from the young supernova to velocities of 12,000 kilometers per second, which account for their broadened emission lines in spectral observations. And that even energy from weak magnetars can accelerate elements from the iron group, which are located deep in the supernova remnant, to 5,000 to 7,000 kilometers per second, which explains why iron is observed early in core-collapse supernovae events like SN 1987A. This has been a long-standing mystery in astrophysics.

Turbulent core of magnetar bubble inside the superluminous supernovae. Color coding shows the densities. The magnetar is located at the center of this image. Strong turbulence is caused by the radiation from the central magnetar. (Image by Ken Chen)

“We were the first ones to accurately model a superluminous supernova system in 3D because we were fortunate to have access to NERSC supercomputers,” said Chen. “This facility is an extremely convenient place to do cutting-edge science.”

In addition to Chen, other authors on the paper are Stan Woosley (University of California, Santa Cruz) and Daniel Whalen (University of Portsmouth and University of Vienna). The team also received technical support from staff at NERSC and Berkeley Lab’s Center for Computational Sciences and Engineering (CCSE).

Chen started using NERSC as a graduate student at the University of Minnesota in 2011, then as the IAU-Gruber Fellow in the Department of Astrophysics at UC Santa Cruz before taking positions at the National Astronomical Observatory of Japan, and his current role at ASIAA.

Written by Linda Vu
Contact: CScomms@lbl.gov

Source: Berkeley Lab Comuting Science/News

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About Computing Sciences at Berkeley Lab

The Computing Sciences Area at Lawrence Berkeley National Laboratory provides the computing and networking resources and expertise critical to advancing Department of Energy Office of Science research missions: developing new energy sources, improving energy efficiency, developing new materials, and increasing our understanding of ourselves, our world, and our universe.

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 13 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab’s facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy’s Office of Science.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

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Ultraviolet light from superluminous supernova key to revealing explosion mechanism

Figure 1: Ultraviolet and visible-light light curves of SLSN Gaia16apd (open cycles) are shown together with calculated light curves for shock-interacting supernova (solid lines, from the paper by Tolstov et al.). UV light of Gaia16apd is 3-4 times brighter than visible light.

An international team of researchers has discovered a way to use observations at ultraviolet (UV) wavelengths to uncover characteristics about superluminous supernovae previously impossible to determine, reports a new study published in Astrophysical Journal Letters on August 3, 2017.

The team, led by Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Project Researcher Alexey Tolstov, studies stellar explosions called Superluminous Supernovae (SLSNe), an extra bright type of supernova discovered in the last decade that is 10 to 100 times brighter than ordinary supernovae. Recently, the team came upon Gaia16apd in a faint dwarf galaxy 1.6 billion light years away.

This SLSNe had an extraordinary UV-bright emission (Figure 1) for a supernova of its kind, but no one could explain what explosion mechanism could produce that feature. Theorists have debated that Gaia16apd could fit one of three SLSNe scenarios. These are the pair-instability supernova, having a large mass of radioactive Nickel-56, or a magnetar-powered supernova where there would be a rapidly spinning and highly magnetized neutron star as an additional energy source, or a shock-interacting supernova where the supernova ejecta would interact with the surrounding dense circumstellar matter (Figure 2).

Figure 2: Artist’s conception of 3 popular SLSN scenarios: shock-interacting, magnetar-powered and pair-instability supernova. SLSN Gaia16apd is most likely a shock-interacting supernova in which radiating shock waves easily produce enormous amounts of UV light. (Credit: Kavli IPMU)

Researchers from Kavli IPMU therefore decided to simulate each model using multicolor radiation hydrodynamics to study light in different colors and ranges of wavelengths and see whether any of the simulations matched with the observed supernova. These simulations produced ultraviolet, visible-light and infrared light curves, photospheric radius and velocity, making it possible to investigate the appearance of the explosion at any wavelength.

Not only did they discover that Gaia16apd was most likely a shock-interacting supernova, Tolstov and his team found a way to model three different scenarios at UV wavelengths using the same numerical technique. In the future, their technique could help researchers in identifying the explosion mechanism of supernova they observe.

“The current study makes one more step to the understanding of the physics of superluminous supernova and helps to identify the scenario of the explosion. The observations and more detailed modeling of the peculiar objects similar to Gaia16apd are highly in demand to find out the nature of the phenomenon of superluminous supernovae,” said Tolstov.

The next step in their research will be to apply simulations on other SLSNe, and make more realistic models by considering the asymmetry of the explosion and physics of the magnetar-powered supernova.

Researchers: (from left to right) Alexey Tolstov, Andrey Zhiglo, and Ken'ichi Nomoto 

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Paper Details：

Journal: Astrophysical Journal Letters

Title: ULTRAVIOLET LIGHT CURVES OF GAIA16APD IN SUPERLUMINOUS SUPERNOVA MODELS

Authors: Alexey Tolstov1, Andrey Zhiglo1,2, Ken'ichi Nomoto1, Elena Sorokina3, Alexandra Kozyreva4, Sergei Blinnikov5,6,1

1 Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The

University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan

2 NSC Kharkov Institute of Physics and Technology, 61108 Kharkov, Ukraine

3 Sternberg Astronomical Institute, M.V.Lomonosov Moscow State University, 119234 Moscow, Russia

4 The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel

5 Institute for Theoretical and Experimental Physics (ITEP), 117218 Moscow, Russia and

6 All-Russia Research Institute of Automatics (VNIIA), 127055 Moscow, Russia

DOI: 10.3847/2041-8213/aa808e (Published 3 August, 2017)

Paper abstract (Astrophysical Journal)
Preprint (arXiv.org)



Images

You can download all images at the following link: http://web.ipmu.jp/press/201709-uvOpt/index.html

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Research contacts

Alexey Tolstov
Project Researcher
Kavli Institute for the Physics and Mathematics of the Universe
The University of Tokyo
E-mail: alexey.tolstov@ipmu.jp

Ken'ichi Nomoto
Senior Scientist
Kavli Institute for the Physics and Mathematics of the Universe
The University of Tokyo
TEL: +81-04-7136-6567
E-mail: nomoto@astron.s.u-tokyo.ac.jp


Media Contact

Motoko Kakubayashi
Press Officer
Kavli Institute for the Physics and Mathematics of the Universe,
The University of Tokyo Institutes for Advanced Study,
The University of Tokyo
TEL: +81-04-7136-5980
E-mail: press@ipmu.jp

Source: Kavli Institute for the Physics and Mathematics of the Universe (Klavi IMPU)

Superluminous supernova marks the death of a star at cosmic high noon

The yellow arrow marks the superluminous supernova DES15E2mlf in this false-color image of the surrounding field. This image was observed with the Dark Energy Camera (DECam) gri-band filters mounted on the Blanco 4-meter telescope on December 28, 2015, around the time when the supernova reached its peak luminosity. (Observers: D. Gerdes and S. Jouvel)

At a distance of 10 billion light years, a supernova detected by the Dark Energy Survey team is one of the most distant ever discovered and confirmed

The death of a massive star in a distant galaxy 10 billion years ago created a rare superluminous supernova that astronomers say is one of the most distant ever discovered. The brilliant explosion, more than three times as bright as the 100 billion stars of our Milky Way galaxy combined, occurred about 3.5 billion years after the big bang at a period known as "cosmic high noon," when the rate of star formation in the universe reached its peak.

Superluminous supernovae are 10 to 100 times brighter than a typical supernova resulting from the collapse of a massive star. But astronomers still don't know exactly what kinds of stars give rise to their extreme luminosity or what physical processes are involved.

The supernova known as DES15E2mlf is unusual even among the small number of superluminous supernovae astronomers have detected so far. It was initially detected in November 2015 by the Dark Energy Survey (DES) collaboration using the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile. Follow-up observations to measure the distance and obtain detailed spectra of the supernova were conducted with the Gemini Multi-Object Spectrograph on the 8-meter Gemini South telescope.

The investigation was led by UC Santa Cruz astronomers Yen-Chen Pan and Ryan Foley as part of an international team of DES collaborators. The researchers reported their findings in a paper published July 21 in the Monthly Notices of the Royal Astronomical Society.

The new observations may provide clues to the nature of stars and galaxies during peak star formation. Supernovae are important in the evolution of galaxies because their explosions enrich the interstellar gas from which new stars form with elements heavier than helium (which astronomers call "metals").

"It's important simply to know that very massive stars were exploding at that time," said Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz. "What we really want to know is the relative rate of superluminous supernovae to normal supernovae, but we can't yet make that comparison because normal supernovae are too faint to see at that distance. So we don't know if this atypical supernova is telling us something special about that time 10 billion years ago."

Previous observations of superluminous supernovae found they typically reside in low-mass or dwarf galaxies, which tend to be less enriched in metals than more massive galaxies. The host galaxy of DES15E2mlf, however, is a fairly massive, normal-looking galaxy.

"The current idea is that a low-metal environment is important in creating superluminous supernovae, and that's why they tend to occur in low mass galaxies, but DES15E2mlf is in a relatively massive galaxy compared to the typical host galaxy for superluminous supernovae," said Pan, a postdoctoral researcher at UC Santa Cruz and first author of the paper.

Foley explained that stars with fewer heavy elements retain a larger fraction of their mass when they die, which may cause a bigger explosion when the star exhausts its fuel supply and collapses.

"We know metallicity affects the life of a star and how it dies, so finding this superluminous supernova in a higher-mass galaxy goes counter to current thinking," Foley said. "But we are looking so far back in time, this galaxy would have had less time to create metals, so it may be that at these earlier times in the universe's history, even high-mass galaxies had low enough metal content to create these extraordinary stellar explosions. At some point, the Milky Way also had these conditions and might have also produced a lot of these explosions."

"Although many puzzles remain, the ability to observe these unusual supernovae at such great distances provides valuable information about the most massive stars and about an important period in the evolution of galaxies," said Mat Smith, a postdoctoral researcher at University of Southampton. The Dark Energy Survey has discovered a number of superluminous supernovae and continues to see more distant cosmic explosions revealing how stars exploded during the strongest period of star formation.

In addition to Pan, Foley, and Smith, the coauthors of the paper include Lluís Galbany of the University of Pittsburgh, and other members of the DES collaboration from more than 40 institutions. This research was funded the National Science Foundation, The Alfred P. Sloan Foundation, and the David and Lucile Packard Foundation.

The Dark Energy Survey is a collaboration of more than 400 scientists from 26 institutions in seven countries. Its primary instrument, the 570-megapixel Dark Energy Camera, is mounted on the 4-meter Blanco telescope at the National Optical Astronomy Observatory's Cerro Tololo Inter-American Observatory in Chile, and its data are processed at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign. Funding for the DES Projects has been provided by the U.S. Department of Energy Office of Science, U.S. National Science Foundation, Ministry of Science and Education of Spain, Science and Technology Facilities Council of the United Kingdom, Higher Education Funding Council for England, ETH Zurich for Switzerland, National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, Kavli Institute of Cosmological Physics at the University of Chicago, Center for Cosmology and Astro-Particle Physics at Ohio State University, Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and Ministério da Ciência e Tecnologia, Deutsche Forschungsgemeinschaft, and the collaborating institutions in the Dark Energy Survey, the list of which can be found at www.darkenergysurvey.org/collaboration.

Source: University of California Santa Cruz

 

Probing the nature of the most luminous explosions

These two images show observations of a superluminous supernova detected by the Palomar Transient Factory project in 2009 (PTF09cnd, z= 0.258). The pre-explosion image is from Sloan Digital Sky archive data, the post-explosion images are composed from observations made with the Palomar Observatory’s 1.5-m telescope, the Wise Observatory’s 1.0-m telescope and the Ultraviolet/Optical Telescope on board NASA’s Swift satellite. Credit: Quimby et al., Nature 474, 487–489 (23 June 2011)

Supernovae are extremely bright stellar explosions – superluminous supernovae are even brighter. However, the nature of these most luminous explosions has remained a mystery. In a new study, MPA researchers now present their simulations of superluminous supernova spectra months and even years after the outbreak and show that they are very similar to gamma-ray bursts, another type of highly energetic explosions. In addition, the results point to very high masses of oxygen and magnesium, suggesting very massive progenitor stars that will use an exotic explosion mechanism rather than the standard neutrino-driven explosion believed to power most supernovae.

Superluminous supernovae are a new and exotic class of stellar explosions, radiating up to 100 times more energy than normal supernovae. Despite being so bright, they were discovered only about 10 years ago, as they occur at large distances and are quite rare (one per every thousand normal supernovae).

The origin of the enormous luminosity and the properties of the progenitor stars have been shrouded in mystery. They may be powered by rapidly spinning and highly magnetized neutron stars (so called magnetars), accretion onto a newly formed black hole, huge amounts of radioactivity, or violent collisions with dense circumstellar matter. What type of progenitor stars give rise to them? Why do they occur exclusively in unusual dwarf galaxies?

In a new study led by Dr Anders Jerkstrand, a Marie Curie Fellow at MPA, several important new advances are presented, which are based on calculating spectral models of supernovae. “Several months and years after the supernova has exploded, when the ejected material expands and cools, the spectra reveal signatures of the elements that have been produced inside the star,” Jerkstrand explains. “By comparing observed to modelled spectra in this phase, we can get an insight into the inner layers of the progenitor, which in turn provides strong constraints on the origin and nature of these explosions.”

Spectra of new observational data of two superluminous supernovae, observed between 2014/02 and 2016/03 with the VLT telescope, including line identifications. Also shown is a rereduced spectrum of a third superluminous supernova, originally observed in 2008 (Gal-Yam+2009). © MPA 

Interpretation of the spectra requires sophisticated models of how radiation passes through the expanding gas and requires the latest atomic physics to be included in the detailed models. What made this study unique was the combination of state-of-the-art new models applied to the highest-quality data ever collected on these supernovae at such late times by the PESSTO survey with the European Southern Observatory's facilities.

The study reveals the first clear picture of the chemical composition of these explosions. The new spectra are demonstrated to have strong similarities with gamma-ray burst supernovae, the first time this link has been established. Gamma-ray burst supernovae are thought to arise by the formation of a black hole that punches a relativistic jet through the infalling star, or by the formation of a highly magnetic neutron star. Gamma ray bursts are similarly rare as superluminous supernovae, and also occur in irregular dwarf galaxies at low metallicity. Some of them are actually accompanied with supernovae, but until now always at much lower luminosities, and not lasting as long as superluminous supernovae.

Interpretation of the spectra requires sophisticated models of how radiation passes through the expanding gas and requires the latest atomic physics to be included in the detailed models. What made this study unique was the combination of state-of-the-art new models applied to the highest-quality data ever collected on these supernovae at such late times by the PESSTO survey with the European Southern Observatory's facilities.

The study reveals the first clear picture of the chemical composition of these explosions. The new spectra are demonstrated to have strong similarities with gamma-ray burst supernovae, the first time this link has been established. Gamma-ray burst supernovae are thought to arise by the formation of a black hole that punches a relativistic jet through the infalling star, or by the formation of a highly magnetic neutron star. Gamma ray bursts are similarly rare as superluminous supernovae, and also occur in irregular dwarf galaxies at low metallicity. Some of them are actually accompanied with supernovae, but until now always at much lower luminosities, and not lasting as long as superluminous supernovae.

This figure shows the observed oxygen line luminosities (gray band) compared to models with different oxygen-zone masses (3,10 and 30 solar masses). This illustrates that the oxygen mass has to be fairly high to match the observations over a broad range of energy inputs. © MPA

In a second important discovery, the spectral synthesis models revealed that these superluminous supernovae contain among the highest oxygen masses inferred for any supernova so far. The spectra show very strong emission lines requiring more than about 10 solar masses of oxygen and 1 solar mass of magnesium. These explosions must therefore come from extremely massive stars, with over 40 solar masses on the main sequence. Stars in this mass range are unlikely to explode with the large inferred kinetic energies by the standard neutrino-driven mechanism, and a more exotic mechanism such as a magneto-rotational driven jets or black hole accretion is needed.

Detailed multi-dimensional models involving the collapse, explosion, and late-time energy input of the massive stellar core are currently being pursued by several groups around the world. Together with the new constraints derived in this study, this promises to expand our knowledge of stellar evolution and supernova explosions into new and unexplored regimes.


Contact:

Jerkstrand, Anders

Postdoc

Phone: 2282

Email: anders@mpa-garching.mpg.de

Source:  Max Planck Institute for Astrophysics

Violent Collision of Massive Supernova with Surrounding Gas Powers Superluminous Supernovae

Artist's conception of a shock-interacting supernova. Successive eruptions of a massive star produce ejecta with different velocities: the blue ring corresponds to slowly moving layers which are punched by fast ejecta (red-to-yellow) which shoots out. Interaction of those gas masses is via radiating shock waves which produce enormous amounts of light. This explains the phenomenon of Superluminous Supernovae with minimum requirements to the energy budget of explosions. (Credit: Kavli IPMU). Large Size jpg / Medium size jpg

Absolute u-band light curves for a fast-fading SLSN-I SN 2010gx and for a slowly fading one PTF09cnd are shown together with two calculated light curves for models N0 and B0 (from the paper by Sorokina et al.), which demonstrates that the interacting scenario can explain both narrow and broad light curves. The light curve of the typical (with “normal” luminosity) SN Ic, SN 1994I, is plotted for comparison. (Credit: Kavli IPMU). Large Size jpg / Medium size jpg

In a unique study, an international team of researchers including members from the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) simulated the violent collisions between supernovae and its surrounding gas— which is ejected before a supernova explosion, thereby giving off an extreme brightness.

Many supernovae have been discovered in the last decade with peak luminosity one-to-two orders of magnitude higher than for normal supernovae of known types. These stellar explosions are called Superluminous Supernovae (SLSNe).

Some of them have hydrogen in their spectra, while some others demonstrate a lack of hydrogen. The latter are called Type I, or hydrogen-poor, SLSNe-I. SLSNe-I challenge the theory of stellar evolution, since even normal supernovae are not yet completely understood from first principles.

Led by Sternberg Astronomical Institute researcher Elena Sorokina, who was a guest investigator at Kavli IPMU, and Kavli IPMU Principal Investigator Ken’ichi Nomoto, Scientific Associate Sergei Blinnikov, as well as Project Researcher Alexey Tolstov, the team developed a model that can explain a wide range of observed light curves of SLSNe-I in a scenario which requires much less energy than other proposed models.

The models demonstrating the events with the minimum energy budget involve multiple ejections of mass in presupernova stars. Mass loss and buildup of envelopes around massive stars are generic features of stellar evolution. Normally, those envelopes are rather diluted, and they do not change significantly the light produced in the majority of supernovae.

In some cases, large amount of mass are expelled just a few years before the final explosion. Then, the “clouds” around supernovae may be quite dense. The shockwaves produced in collisions of supernova ejecta and those dense shells may provide the required power of light to make the supernova much brighter than a “naked” supernova without pre-ejected surrounding material.

This class of the models is referred to as “interacting” supernovae. The authors show that the interacting scenario is able to explain both fast and slowly fading SLSNe-I, so the large range of these intriguingly bright objects can in reality be almost ordinary supernovae placed into extraordinary surroundings.

Another extraordinarity is the chemical composition expected for the circumstellar “clouds.” Normally, stellar wind consists of mostly hydrogen, because all thermonuclear reactions happen in the center of a star, while outer layers are hydrogenous.

In the case of SLSNe-I, the situation must be different. The progenitor star must lose its hydrogen and a large part of helium well before the explosion, so that a few months to a few years before the explosion, it ejects mostly carbon and oxygen, and then explode inside that dense CO cloud. Only this composition can explain the spectral and photometric features of observed hydrogen-poor SLSNe in the interacting scenario.

It is a challenge for the stellar evolution theory to explain the origin of such hydrogen- and helium-poor progenitors and the very intensive mass loss of CO material just before the final explosion of the star. These results have been published in a paper accepted by The Astrophysical Journal.

Details of the paper were published in September’s The Astrophysical Journal.

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Paper Details:

Journal:
The Astrophysical Journal

Title: 
Type I Super-luminous Supernovae as Explosions inside Non-Hydrogen Circumstellar Envelopes

Authors:

E.I. Sorokina (1), S.I. Blinnikov (2), K. Nomoto (3), R. Quimby (4), and A. Tolstov (5)

1. Elena Sorokina, Sternberg Astronomical Institute, Moscow State University, GSP-1, Leninskie Gory, 119991 Moscow, Russia
2. S. I. Blinnikov, Institute for Theoretical and Experimental Physics, 117218 Moscow, Russia
3. Ken’ichi Nomoto, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan
4. Robert Quimby, Cahill Center for Astrophysics, California Institute of Technology, 1200 E. California Blvd., MC 249-17 Pasedena, CA 91125
5. Alexey Tolstov, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan

DOI: 10.3847/0004-637X/829/1/17 (Published September 15, 2016)

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Paper abstract

(The Astrophysical Journal): Link

arXiv.org: 1510.00834, October 2015.

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Research contact:

Ken’ichi Nomoto
Principal Investigator and Project Professor
Kavli Institute for the Physics and Mathematics of the Universe
TEL: +81-04-7136-6567
E-mail: nomoto@astron.s.u-tokyo.ac.jp

Alexey Tolstov
Project Researcher
Kavli Institute for the Physics and Mathematics of the Universe
E-mail: alexey.tolstov@ipmu.jp

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Useful links: The Astrophysical Journal

Related links: Kavli IPMU press release: “Magnetar could have boosted explosion of extremely bright supernova”

All images, including those of some of the authors, can be downloaded from here.

Source: Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)