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Galaxies Are Dying And Now Scientists Know Why

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An astronomic phenomenon, called ram-pressure stripping, drives gas from galaxies and condemns them to premature death because of the deprivation of material needed for the process of star formation. The research investigating this occurrence was conducted by a global team of researchers.

The study, published Jan. 16, in the journal Monthly Notices of the Royal Astronomical Society, was carried out at the International Centre for Radio Astronomy Research as an attempt to better understand this phenomenon and its consequences.

Ram-Pressure Stripping, Responsible For Premature Star Death

The research analyzed 10,600 satellite galaxies and concluded that the gas is stripped away at a very fast pace all over the local universe. The gas is a vital element when it comes to star formation, without which these cannot be created.

The universe, as we know it, is composed of matter, accounting for approximately 5 percent of the entire universe; dark matter, accounting for approximately 27 percent; and dark energy, accounting for the rest of 68 percent of our universe.

Toby Brown, lead researcher and a PhD candidate at ICRAR, noted that galaxies are embedded in clouds of dark matter, carrying the name of dark matter halos.

"During their lifetimes, galaxies can inhabit halos of different sizes, ranging from masses typical of our own Milky Way to halos thousands of times more massive. As galaxies fall through these larger halos, the superheated intergalactic plasma between them removes their gas in a fast-acting process called ram-pressure stripping," Brown noted.

The process threatens the existing stars, as these cool off in the absence of gas, grow old, and die. The phenomenon also obstructs new stars from being formed.

Prior to this research, it was known that the ram-pressure stripping phenomenon had an effect of galaxies in clusters. However, this new study shows that galaxies can be affected even on a significantly smaller level, when there is notably less dark matter around the galaxies.

The vast majority of galaxies in our universe exist in groups, ranging between two to a hundred, which obstructs star formation on a large level, affecting all the galaxies that are part of the cluster.

"Our results are then compared with state-of-the-art semi-analytic models and hydrodynamical simulations and discussed within this framework, showing that more work is needed if models are to reproduce the observations. We conclude that the observed decrease of gas content in the group and cluster environments cannot be reproduced by starvation of the gas supply alone and invoke fast acting processes such as ram-pressure stripping of cold gas to explain this," noted the research.

The Observable Universe, Ten Times Larger Than Initially Thought

However, while this situation raises concern among specialists, another recent study, published in October 2016, suggests that there actually are ten times more galaxies in the observable universe than previously thought.

"The missing 90 percent of the universe's galaxies are too faint and too far away to be detected by the current crop of telescopes, including Hubble. To uncover them, astronomers will have to wait for much larger and more powerful future telescopes. The researchers arrived at their result by painstakingly converting Hubble deep-field images into 3-D pictures so they could make accurate measurements of the number of galaxies at different epochs in the universe's history," stated the paper's press release.

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