SPACE/COSMOS
Magnetic fields in the infant universe may have been billions of times weaker than a fridge magnet
The magnetic fields that formed in the very early stages of the Universe, may have been billions of times weaker than a small fridge magnet, with strengths comparable to magnetism generated by neurons in the human brain. Yet, despite such weakness, quantifiable traces of their existence still remain in the cosmic web, the visible cosmic structures connected throughout the Universe. These conclusions emerge from a study using around a quarter of a million computer simulations, conducted by a team from SISSA (the International School for Advanced Studies based in Trieste) in collaboration with the Universities of Hertfordshire, Cambridge, Nottingham, Stanford, and Potsdam. Observational data were subsequently used to validate these findings. The research, recently published in Physical Review Letters, specifies both possible and maximum values for the strengths of primordial magnetic fields. It also offers the possibility of refining our knowledge of the early Universe and the formation of the first stars and galaxies.
A magnetic cosmic web
“The cosmic web, of which much remains to be discovered, is a filamentary structure connecting the galaxies that permeates the Universe. One of its many unsolved mysteries is why it is magnetised, not only near galaxies, where this might be expected, but also in distant regions that are sparsely populated and constitute the bulk of the cosmic web. This is harder to explain”. These comments come from Mak Pavičević, a SISSA PhD student and lead author of the research, and Matteo Viel, his supervisor and co-author of the study. "Our hypothesis was that this could be a legacy of events occurring in cosmic epochs during the birth of the Universe, and that magnetism was linked essentially to physical processes in the primordial Universe. For example, the filaments would have become magnetised during the inflation process before the so-called "Big Bang" or through events in later epochs, called phase transitions. This is what we sought to ascertain with our work. We also wished to assess the magnitude of these primordial magnetic fields through our investigations, establishing an upper limit and attempting to measure their strengths."
At the origin of the Universe with a quarter of a million simulations
The international team used over 250,000 computer simulations to study the cosmic web and better understand the influence of primordial magnetic fields. Vid Iršič from University of Hertfordshire, and a co-author of the study, emphasises that “these are the most realistic and largest suite state-of-the-art simulations of the influence of primordial magnetic field on the intergalactic cosmic web.” Pavičević and Viel explain: "By comparing these simulations with observational data, we saw that our hypotheses were correct. When the influence of primordial fields is included in the picture, the cosmic web looks different and more in agreement with observed data. In particular, we can say that a standard model of the Universe with a very weak magnetic field of around 0.2 nano-gauss actually fits experimental data much better."
The magnitude of primordial magnetic fields: a new upper limit
The scientists have derived a particularly low value for the magnitude of the primordial magnetic fields, establishing a new upper limit several times lower than previously estimated. Pavičević and Viel continue: "Our research thus places strict limits on the intensity of magnetic fields formed in the very early moments of the Universe and is consistent with recent results obtained in independent data and studies on the cosmic microwave background. The two scientists explain: "This evidence will help us to improve our understanding of events in the early Universe. The magnetic field would have increased the density of the cosmic web, in turn accelerating the process of star and galaxy formation. It will be possible to further validate our results through observations made by the James Webb Space Telescope." Vid Iršič concludes: “Not only will these new limits help us understand the impact of the primordial magnetic fields on the evolution of the Cosmo, but they also hold important implications for other theoretical models that enhance structure formation”.
Journal
Physical Review Letters
Method of Research
Computational simulation/modeling
$1.39 million grant to enhance CHARA Array’s vision
The observatory is set to unveil the cosmos in sharper focus, capturing stars across the visible and near-infrared spectrum like never before
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The CHARA Array is set to unveil the cosmos in sharper focus, capturing stars across the visible and near-infrared spectrum like never before.
view moreCredit: Courtesy: Georgia State University
ATLANTA — A new $1.39 million grant from the National Science Foundation (NSF) will upgrade Georgia State University’s CHARA Array, giving it the ability to observe stars across the full visible and near-infrared spectrum.
The funding from the NSF’s Major Research Instrumentation Program will equip the Center for High Angular Resolution Astronomy (CHARA) Array with state-of-the-art optics, controllers and a sensitive tracking detector, allowing simultaneous observations across visible and near-infrared wavelengths. The advancement will allow researchers and students from around the world to explore the universe — from local star systems to distant galaxies — in unprecedented detail.
“It’s incredibly rewarding to see what’s possible when curiosity meets cutting-edge technology,” said Array Director Gail Schaefer. “We are committed to delivering a world-class experience for astronomers exploring the cosmos and this upgrade gives our scientists a powerful new way to image stars in different wavelengths at the same time.”
What Is the Array and How Does It Work?
The CHARA Array is a powerful telescope system used to study stars and other objects in space in incredible detail. It’s made up of six separate telescopes that work together as one giant telescope. This setup allows scientists to see extremely fine detail.
The telescopes, spread across a large area on Mount Wilson in California, combine their light using a technique called interferometry. It’s as if six eyes are all looking at the same object, and those views are merged to form one crystal-clear image.
Operated by Georgia State University, CHARA is like a super-precise cosmic zoom lens that helps astronomers get a closer, clearer look at the universe.
What’s New?
With the upgraded instrumentation expected to come online in 2028, experts expect a fresh surge of new discoveries. From exploring stellar nurseries to mapping the fabric of the universe, the upgraded array will remain a cornerstone of Georgia State’s scientific infrastructure for years to come.
“The CHARA Array hosts state-of-the-art cameras built by partners at the University of Michigan, the University of Exeter (UK) and the Université de la Côte d’Azur (France), but we had difficulties using them together,” explained Doug Gies, Regents' Professor of Physics and Astronomy and director of CHARA. “With this new NSF award, we will soon have the means to use them simultaneously across the color spectrum. With these new capabilities, CHARA will be able to explore the universe with unprecedented clarity, inspiring new discoveries and a new generation of astronomers.”
Georgia State Provost and Executive Vice President for Academic Affairs Nicolle Parsons-Pollard shared her pride in the progress of the university’s astronomy program and its commitment to supporting world-class research.
“This is outstanding news and a significant achievement for both CHARA and Georgia State University,” she said. “The enhanced ability to observe stars across the full spectrum of visible and near-infrared light marks a remarkable advancement, firmly positioning Georgia State at the forefront of astronomical research.”
The CHARA Array is funded by the National Science Foundation. Institutional support for the CHARA Array is provided from Georgia State’s College of Arts & Sciences and the Office of the Provost.
For more information about Georgia State University research and its impact, visit research.gsu.edu. For more information about the CHARA Array, visit the CHARA Array website.
New study reveals origin of the fastest white dwarfs in the galaxy
New study uncovers explosive pathway to hypervelocity white dwarfs and unusual Type Ia supernovae
Technion-Israel Institute of Technology
In a breakthrough study published in Nature Astronomy, researchers have discovered a new origin for some of the fastest stars ever observed: hypervelocity white dwarfs — compact stellar remnants hurtling through space faster than 2000 km/s.
Led by Dr. Hila Glanz of the Technion – Israel Institute of Technology, the international team performed state-of-the-art three-dimensional hydrodynamic simulations of a merger between two rare hybrid helium–carbon–oxygen white dwarfs. The results reveal a dramatic sequence of events: as the lighter star is partially disrupted, the heavier one undergoes a double-detonation explosion, slingshotting the surviving remnant of its companion into space at hypervelocity speeds exceeding 2000 kilometers per second — fast enough to escape the gravitational grip of the Milky Way.
“This is the first time we've seen a clean pathway where the remnants of a white dwarf merger can be launched at hypervelocity, with properties matching the hot, faint white dwarfs we observe in the halo,” said Dr. Glanz. “This solves the mystery about the origin of these stellar runaways — and also opens up a new channel for faint and peculiar Type Ia supernovae.”
Unlike previously proposed scenarios, the new model accounts for both the extreme velocities and unusual temperatures and brightness of known HVWDs, such as the stars J0546 and J0927. It also offers insight into underluminous thermonuclear explosions, which are crucial tools for measuring the universe’s expansion and for understanding how elements are formed in galaxies.
“This discovery doesn’t just help us understand hypervelocity stars — it gives us a window into new kinds of stellar explosions,” said co-author Prof. Hagai Perets, also of the Technion.
The study was conducted by researchers from the Technion, Universität Potsdam, and the Max Planck Institute for Astrophysics, combining high-performance simulations with new theoretical modeling.
The work has implications for upcoming transient surveys and Gaia data releases, which may uncover more of these elusive stellar cannonballs flying through the galaxy.
Journal
Nature Astronomy
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
The origin of hypervelocity white dwarfs in the merger disruption of He–C–O white dwarfs
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