Astronomers have naturally focused their telescopes on the part of the universe closest to us, as those stars and galaxies can be examined in the most detail. But astrophysicists sometimes struggle to balance the population of our galactic neighborhood with dark matter theories. For example, previous models predicted more neighboring galaxies than were actually detected in the real universe, a problem known as the “missing satellite” problem.
Large clumps of dark matter must have enough gravity to bring gas to accumulate into stars and later galaxies. But another problem is that some simulations end up producing large orbits, dark matter masslooks like these Candlestick hosts satellite galaxies — but they don’t appear to have any real cosmic counterparts. This is known as the “too big to fail” problem, as the giant blobs of dark matter are thought to be too large to form galaxies within them.
A third challenge comes from the fact that the satellite galaxies orbiting the Milky Way and Andromeda appear to be orbiting in a single plane, rather than spreading out around them – something dark matter physicists have already discovered. unpredictable.
There are also cosmological problems that Frenk and his colleagues want to solve. Astronomers using nearby supernova explosions and other local phenomena to measure the rate at which the universe is currently expanding will get different answers than those who probe the early universe. If the dark matter models are correct, there must be a way to solve the problem and persistent difference between past and present observations.
But simulations like SIBELIUS can be useful. It could turn out that where a galaxy lives on the cosmic web of dark matter really makes a difference to measurements of the expansion rate of the universe. What if the Milky Way was in a “hole” in the net – if it were like a countryside among darker matter metropolises? If our part of the universe isn’t truly representative, our local measurements of how fast the universe is blowing outward can be slightly misleading.
The Milky Way could be in a fairly dense dark matter region or in a sparse region, said Priyamvada Natarajan, an astrophysicist and dark matter expert at Yale University. “The exciting thing about this simulation is that they were able to solve: How typical or unusual is our local mass? How rare is the distribution of matter that we see around us? Are we in the mountains or are we in a valley? ” she speaks.
The focus is on the galaxies in the Virgo star cluster, says Jenny Sorce, astrophysicist at the Institut d’Astrophysique Spatiale in Orsay, France. “It’s not like you can compare one type of cluster to another if they don’t have the same history or the same environment,” she said.
Frenk and his team did a lot of early testing with their own computers at low resolution. But the above time Super computer, like on a telescope, is limited. They only had one chance to run their full simulation, which took millions of hours of computation on thousands of computer cores. But based on the results of their simulations, they found that the vicinity of the Milky Way does indeed appear atypical: We live in a region of the universe with fewer galaxies than average, but also many clusters. The galaxy is larger than average. It’s like living in a low-altitude city, like Los Angeles, but with mountains in the distance.
Frenk and Boylan-Kolchin speculate that if the Milky Way is indeed a singularity ball, it could help explain some dark matter mysteries. If we are in a sparse part of the universe, that could explain why the local measurements of the expansion rate are different from what we would expect based on measurements of the distant universe.
And if our galaxy is in the middle of an atypical neighborhood, that could explain why the satellites have an unusual configuration — maybe they’re being pulled into the Milky Way’s orbit in a particular way. body.
In other words, if the Milky Way’s neighborhood is indeed unusual, it means that cold dark matter theory will survive these challenges — for now.
