Far out cosmology: spiral galaxies rarer than elliptical (Introduction)

by David Turell , Saturday, November 25, 2023, 17:38 (362 days ago) @ David Turell

In our region of the universe:

https://www.universetoday.com/164414/there-arent-many-galaxies-like-the-milky-way-nearb...

"The Milky Way is a barred spiral galaxy, maybe even a grand design spiral galaxy. We can’t be sure from our vantage point. But one thing is certain: there aren’t many disk galaxies like it in our part of the Universe called the supergalactic plane.

"We can locate things on Earth using compass points and latitudes and longitudes. But in space, that doesn’t work. Astronomers use the supergalactic coordinate system to describe where galaxies are.

"Part of that coordinate system is the Supergalactic Plane (SGP), which contains the Local Group of galaxies that the Milky Way is in. The SGP is nearly perpendicular to the Milky Way’s plane.

"The supergalactic plane is part of a reference system for the Local Universe. It’s a flat, enormous circle one billion light-years across, though this image only shows part of it. It’s centred on the Local Group, which is where the Milky Way resides.

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"But scientists do know that the SGP is filled with galaxies. Bright elliptical galaxies dominate the SGP, while spirals like the Milky Way are rare. The paucity of spiral galaxies caught the attention of a group of researchers from Europe. They used supercomputer simulations to try to gauge the population and distribution of galaxies in the SGP.

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“'Galaxies of different types are not equally distributed in the Local Universe,” the researchers write in their paper. “The supergalactic plane is prominent among the brightest ellipticals but inconspicuous among the brightest disk galaxies.”

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"Sawala and his colleagues found that the distribution of ellipticals and spirals is because of the different conditions inside and outside of the SGP. Inside, galaxies are more tightly packed together, and outside of the SGP, the galactic density is lower.

"Inside the SGP, galaxies interact and merge with each other more frequently. These interactions change beautiful spirals like the Milky Way into ellipticals, which are basically ellipses or spheres with no discernible arms.

"But outside of the SGP, galaxies interact less frequently. So the Milky Way and others like it are able to retain their form. (my bold)

“'We find that SIBELIUS DARK reproduces the spatial distributions of disks and ellipticals and, in particular, the observed excess of massive ellipticals near the supergalactic equator,” the researchers write.

"The SIBELIUS results are in line with observations, which helps confirm its usefulness. “This mass difference agrees with observational studies of galaxies in the Local Universe, which also find that the most massive galaxies are overwhelmingly elliptical,” Sawala and his colleagues write in their paper.

"To grow large, disk galaxies like the Milky Way need a supply of gas and minimal interactions with other galaxies. That environment is found outside of the SGP. “We conclude that the environment prevailing in the supergalactic plane inhibits the conditions necessary for massive disk formation: a quiet merger history and the continuous supply of cold gas,” the authors explain.

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“'The strikingly different distributions of bright ellipticals and disks in relation to the supergalactic plane do not require physics beyond the standard model,” they write. Instead, the distributions relative to the SGP “arise naturally in the Lambda CDM framework.” The distribution is a part of the standard model of how galaxies form and evolve.

"For us, it doesn’t make much difference whether we live in a spiral/disk galaxy or in an elliptical. But examining how our type of galaxy fits into nature is worth exploring. These results strengthen the already powerful arguments in favour of the Lambda CDM model.

"Now, if we could only figure out what the heck dark matter actually is."

Comment: The SGP is a slice across the plane of the galaxy, a cross-sectional view which is a very informative result. It tells us big spirals are not as common as ellipticals. What does that mean to my theory God is/was designing a universe for us. Is our privileged planet in a privileged galaxy? Note my bold. Merging galaxies create a very chaotic situation as gravity from two directions pulls things apart. For life to continue, the last thing we need is a merger, and in two million years we merge with Andromeda. If God is in charge, does that mean the length of our time of life has limits?