2 days ago
Durham scientists discover more galaxies in Milky Way than previously thought
The Milky Way could be home to more galaxies than initially believed, scientists at Durham University have discovered.
Research by cosmologists at the university suggests there are 80, or possibly even 100, more satellite galaxies orbiting our galaxy at close distances.
They made this prediction using a new technique that combines high-resolution supercomputer simulations and novel mathematical modelling.
If observed by telescopes, the extra galaxies could provide strong support for the Lambda Cold Dark Matter (LCDM) theory, which explains how galaxies form and the large-scale structure of the universe.
Dr Isabel Santos-Santos, lead researcher at the Institute for Computational Cosmology, Department of Physics, Durham University, said: "We know the Milky Way has some 60 confirmed companion satellite galaxies, but we think there should be dozens more of these faint galaxies orbiting around the Milky Way at close distances."
Research will be presented at the Royal Astronomical Society's National Astronomy Meeting, held at Durham University.
(Image: Durham University)
The Durham-led research is based on the LCDM model, where ordinary matter represents only five per cent of the universe's total content, 25 per cent is cold dark matter (CDM), and the remaining 70 per cent is dark energy.
In this model, galaxies form in the centre of large clumps of dark matter called halos.
The research shows the Milky Way's missing satellites are extremely faint galaxies, stripped almost entirely of their parent dark matter halos by the gravity of the Milky Way's halo.
These so-called "orphan" galaxies are lost in most simulations, but should have survived in the real universe.
Dr Santos-Santos added: "One day soon we may be able to see these 'missing' galaxies, which would be hugely exciting and could tell us more about how the universe came to be as we see it today."
The researchers believe that advances in telescopes and instruments like the Rubin Observatory LSST camera, which recently saw its first light, will allow astronomers to detect these very faint objects for the first time.
Their results showed that halos of dark matter, which may host a satellite galaxy, have been orbiting around the central Milky Way halo for most of the age of the universe.
This has led to the stripping of their dark matter and stellar mass, rendering them extremely small and faint.
As a result, the research predicts that the total number of satellite galaxies likely to exist around the Milky Way is around 80, or potentially up to 100 more than currently known.
Professor Carlos Frenk, co-researcher at the Institute for Computational Cosmology, Department of Physics, Durham University, said: "If the population of very faint satellites that we are predicting is discovered with new data, it would be a remarkable success of the LCDM theory of galaxy formation.
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"It would also provide a clear illustration of the power of physics and mathematics.
"It doesn't get much better than this."
The research is funded by the European Research Council and the Science and Technology Facilities Council (STFC).
