Scientists at the University of California, Riverside may be learning a bit more about dark matter, as they've created a new analysis of computer simulations, based on theoretical models, that study the interaction of a dwarf galaxy with a dark satellite.
The current model of the creation of structures of the universe predicts that galaxies are embedded in extended and massive hallows of dark matter. These halos, in turn, are surrounded by many thousands of smaller sub-halos also made from dark matter.
Around large galaxies, these sub-halos are large enough to host enough gas and dust to form small galaxies on their own. Known as satellite galaxies, these galaxies can orbit for billions of years around their host before a possible merger. This merger triggers violent episodes of star births.
Of course, there are even smaller hallows that form dwarf galaxies that are, in turn, orbited by even smaller satellite sub-halos of dark matter. These comparatively tiny halos are invisible to telescopes since they're too tiny to have gas or stars in them. While they're present in models, though, scientists have yet to directly observe their interaction with host galaxies.
In this latest study, the researchers analyzed new computer simulations and found that during a dark satellite's closest approach to a dwarf galaxy, it compresses the gas in the galaxy. This, in turn, triggers starbursts, which are significant periods of star formation that can last for billions of years.
So what does this mean in the larger scope of things? The scenario predicts that many dwarf galaxies that we see today should be forming stars at a higher rate than expected. In other words, they should be experiencing a starburst.
That's not all that the researchers found. The interaction between the dwarf galaxy and the dark satellite triggers morphological changes in the dwarf. This, in turn, can completely change the dwarf galaxy's structure from a mainly disk-shaped to a spherical/elliptical system.
With telescope observations, the research team was able to take a closer look at dwarf galaxies. This revealed that high periods of star formation were occurring in dwarf galaxies. The scientists also found isolated spheroidal dwarf galaxies, a phenomenon that has been unexplained for decades. This means that they were able to find tangible evidence that the simulations were correct.
The findings reveal a bit more about dwarf galaxies and the dark matter satellites that surround them. This, in turn, provides more tangible evidence about how dark matter interacts with galaxies.
The study was published in the Feb. 15 issue of the journal Astronomy and Astrophysics.
