Friday , November 27 2020

Dark fabric on the go



Star formation in small dwarf shrubs can slowly "warm up" the dark matter and push it outward. The left picture shows the hydrogen gas density of a simulated dwarf galaxy seen from above. The right image shows the same for a true dwarf galaxy, IC 1613. In the simulation, repeated gas inflow and outflow causes the gravity field strength in the center of the dwarf to fluctuate. The dark matter responds to this by migrating out of the center of the galaxy, an effect known as "dark matter warming". Credit: J. Read et al.

Scientists have found evidence that dark matter can be heated and moved as a result of star formation in galaxies. The results provide the first observational evidence of the effect known as & quot; dark substance warming & quot; and gives new traces of what constitutes dark matter. The research is published today in the journal Monthly announcements from the Royal Astronomical Society.


In the new work, researchers from the University of Surrey, Carnegie Mellon University and ETH Zurich set out to search for evidence of dark matter in the centers of nearby dwarf salmon. Dwarf salmon are small, weak galaxies, typically found in circuits in larger galaxies like our own Milky Way. They can keep track of what could help us better understand the nature of darkness.

Dark matter is believed to constitute most of the mass of the universe. But since it does not interact with light in the same way as normal material, it can only be seen through its gravity effects. However, the key to studying it may lie in how stars form in these galaxies.

When stars form, strong winds can push gas and dust away from the galaxy's heart. As a result, the galaxy center has less mass, which affects how much gravity is labeled by the remaining dark matter. With less gravity, the dark matter attracts energy and migrates away from the center, an effect called "dark matter warming".

The team of astrophysicists measured the amount of dark matter in the centers of 16 dwarf galaxies with very different star formation histories. They found out that galaxies that stopped forming stars long ago had higher dark material densities at their centers than those still forming stars today. This supports the theory that the older galaxies had less dark matter heating.

Professor Justin Read, lead author of the study and head of the Department of Physics at the University of Surrey, said: "We found a truly remarkable relationship between the amount of dark matter in the centers of these small dwarfs and the amount of star formation they have experienced in the course of their lives, the dark matter in the centers of the star-forming dwarfs seems to have been "heated" and pushed out. "

The results give a new limitation on dark matter models: dark matter must be able to form dwarf galaxies that exhibit a number of central densities, and these densities must be related to the amount of star formation.

Professor Matthew Walker, a co-author of Carnegie Mellon University, added: "This study can be the" smoking gun "certificate that takes us one step closer to understanding what dark matter is. Our discovery that it can be heated and moved around helps motivating searches for a dark stock item. "

The team hopes to expand on this work by measuring the central dark matter density in a larger sample of dwarfs, pushing into even weaker galaxies and testing a wider selection of dark matter models.


Explore further:
Astronomers find that dark matter dominates over cosmic time

More information:
J I read et al. Dark fabric heats up in dwarf galaxies, Monthly announcements from the Royal Astronomical Society (2018). DOI: 10,1093 / mr / ste3404

Journal reference:
Monthly announcements from the Royal Astronomical Society

Supplied by:
University of Surrey


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