November 30, 2023
Physicists answer the question about the absence of spiral galaxies in the Supergalactic Plane

Physicists answer the question about the absence of spiral galaxies in the Supergalactic Plane

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Artistic concept of the Milky Way. Credit: NASA/JPL-Caltech.

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Artistic concept of the Milky Way. Credit: NASA/JPL-Caltech.

Astrophysicists say they have found an answer to why spiral galaxies like our Milky Way are largely absent from a part of our local universe called the Supergalactic Plane.

The Supergalactic Plane is a huge, flat structure that stretches almost a billion light years, in which our galaxy, the Milky Way, is embedded.

Although the Plane is full of bright elliptical galaxies, bright disk galaxies with spiral arms are noticeably scarce.

Now, an international team of researchers, co-led by Durham University in the United Kingdom and the University of Helsinki in Finland, says that different distributions of elliptical and disk galaxies arise naturally due to the contrasting environments found inside and outside the Earth. Flat.

In the dense clusters of galaxies found in the Supergalactic Plane, galaxies experience frequent interactions and mergers with other galaxies. This transforms spiral galaxies into elliptical galaxies – smooth galaxies with no apparent internal structure or spiral arms – and leads to the growth of supermassive black holes.

On the other hand, far from the Plane, galaxies can evolve in relative isolation, which helps them preserve their spiral structure.

The findings are published in the journal Nature Astronomy.


This image, which shows an elliptical galaxy (left) and a spiral galaxy (right), includes near-infrared light from the James Webb Space Telescope and ultraviolet and visible light from the Hubble Space Telescope. Credit: NASA, ESA, CSA, Rogier Windhorst (ASU), William Keel (University of Alabama), Stuart Wyithe (University of Melbourne), JWST PEARLS team, Alyssa Pagan (STScI).

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This image, which shows an elliptical galaxy (left) and a spiral galaxy (right), includes near-infrared light from the James Webb Space Telescope and ultraviolet and visible light from the Hubble Space Telescope. Credit: NASA, ESA, CSA, Rogier Windhorst (ASU), William Keel (University of Alabama), Stuart Wyithe (University of Melbourne), JWST PEARLS team, Alyssa Pagan (STScI).

The Milky Way is part of the Supergalactic Plane, which contains several massive galaxy clusters and thousands of individual galaxies. The vast majority of galaxies found here are elliptical galaxies.

The research team used the supercomputer simulation SIBELIUS (simulations beyond the local universe), which tracks the evolution of the universe over 13.8 billion years, from the beginning of the universe to the present day.

While most cosmological simulations consider random fragments of the universe, which cannot be directly compared with observations, SIBELIUS aims to accurately reproduce observed structures, including the Supergalactic Plane. The final simulation is remarkably consistent with observations of our universe through telescopes.

Research co-author Professor Carlos Frenk, Ogden Professor of Fundamental Physics at the Institute of Computational Cosmology at Durham University, said: “The distribution of galaxies in the Supergalactic Plane is truly remarkable.

“It’s rare, but not a complete anomaly: our simulation reveals the intimate details of galaxy formation, such as the transformation of spirals into ellipticals through galaxy mergers.

“Furthermore, the simulation shows that our standard model of the Universe, based on the idea that most of its mass is cold, dark matter, can reproduce the Universe’s most remarkable structures, including the spectacular structure of which the Milky Way is part of it. ”


Distribution of the brightest galaxies in the local universe, observed in the 2MASS survey (left panel) and reproduced in the SIBELIUS simulation (right panel). Both panels show projections in supergalactic coordinates, up to approximately 100 Megaparsec (Mpc). The nearly vertical empty band represents the region of sky hidden behind our galaxy, the Milky Way. The simulation accurately reproduces the structures seen in the local universe. Credit: Dr. Till Sawala

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Distribution of the brightest galaxies in the local universe, observed in the 2MASS survey (left panel) and reproduced in the SIBELIUS simulation (right panel). Both panels show projections in supergalactic coordinates, up to approximately 100 Megaparsec (Mpc). The nearly vertical empty band represents the region of sky hidden behind our galaxy, the Milky Way. The simulation accurately reproduces the structures seen in the local universe. Credit: Dr. Till Sawala

The peculiar separation between spiral and elliptical galaxies in the local universe, which has been known since the 1960s, features prominently in a recent list of “cosmic anomalies” compiled by renowned cosmologist and 2019 Nobel laureate Professor Jim Peebles.

Lead author Till Sawala, a postdoctoral researcher at the University of Durham and the University of Helsinki, said: “By chance, I was invited to a symposium in honor of Jim Peebles last December in Durham, where he presented the problem in your lecture.

“And I realized that we had already completed a simulation that could hold the answer. Our research shows that the known mechanisms of galaxy evolution also work in this unique cosmic environment.”

Supercomputer simulations were carried out on the Cosmology Machine (COSMA 8) supercomputer, hosted by Durham University’s Institute for Computational Cosmology on behalf of the UK’s DiRAC High-Performance Computing facility, and on CSC’s Mahti supercomputer in Finland.

More information:
Distinct distributions of elliptical and disk galaxies across the Local Supercluster as a ΛCDM prediction, Nature Astronomy (2023). DOI: 10.1038/s41550-023-02130-6

Diary information:
Nature Astronomy

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