These Dwarf Galaxies Seem to Be Devoid of Dark Matter, And It Doesn't Make Sense
CAROLYN COLLINS PETERSEN, UNIVERSE TODAY8 AUGUST 2022
Ask astronomers about dark matter and one of the things they talk about is that this invisible, mysterious 'stuff' permeates the universe. In particular, it exists in halos surrounding most galaxies.
The mass of the halo exerts a strong gravitational influence on the galaxy itself, as well as on others in the neighborhood. That's pretty much the standard view of dark matter and its influence on galaxies.
However, there are problems with the idea of those halos. Apparently, some oddly shaped dwarf galaxies exist that look like they have no halos. How could this be? Do they represent an observationally induced challenge to the prevailing ideas about dark matter halos?
Finding Perturbed Dwarf Galaxies
In the so-called "Standard Model" of cosmology, shells or halos of dark matter protect galaxies from the gravitational influence of nearby galactic neighbors.
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https://www.sciencealert.com/these-dwarf-galaxies-seem-to-be-avoiding-dark-matter-somehow
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No trace of dark matter halos.
BY
AMIT MALEWAR
AUGUST 6, 2022 17:07 IST
The dwarf galaxy NGC1427A flies through the Fornax galaxy cluster and undergoes disturbances which would not be possible if this galaxy were surrounded by a heavy and extended dark matter halo, as required by standard cosmology. Credit: ESO
The standard model of cosmology suggests that a halo of dark matter particles surrounds most galaxies. However, this halo of dark matter is invisible, but its mass exerts a strong gravitational pull on galaxies in the vicinity.
A new study by the University of Bonn (Germany) and the University of Saint Andrews (Scotland) challenges this Universe view. The results suggest that the dwarf galaxies of Earth’s second closest galaxy cluster—known as the Fornax Cluster—are free of such dark matter halos.
Scientists, in particular, have introduced an innovative way of testing the standard model based on how much dwarf galaxies are disturbed by gravitational tides’ from nearby larger galaxies.
Elena Asencio, a Ph.D. student at the University of Bonn and the lead author of the story, said, “Tides arise when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth, which arise because the moon pulls more strongly on the side of Earth which faces the moon.”
More:
https://www.techexplorist.com/dwarf-galaxies-earth-second-closest-galaxy-cluster-free-dark-matter-halos/52939/