Ask astronomers about dark matter and one of the things they talk about is that this invisible, mysterious “stuff” permeates the universe. In particular, it exists in halos surrounding most galaxies. The mass of the halo exerts a strong gravitational influence on the galaxy itself, as well as on others in the neighborhood. That’s pretty much the standard view of dark matter and its influence on galaxies. However, there are problems with the idea of those halos. Apparently, some oddly shaped dwarf galaxies exist that look like they have no halos. How could this be? Do they represent an observationally induced challenge to the prevailing ideas about dark matter halos?Continue reading “Dwarf Galaxies Found Without Influence From Dark Matter”
Although the particles of dark matter continue to allude us, astronomers continue to find evidence of it. In a recent study, they have seen its effect from the edge of visible space, when the universe was just 1.5 billion years old.Continue reading “Astronomers Measure the Signal of Dark Matter From 12 Billion Years ago”
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Individual contributors have become less and less prominent in scientific fields as the discipline itself has matured. Some individuals still hold the public spotlight for their discoveries, such as Peter Higgs with the Higgs boson, which several other physicists also theorized around the same time he did. However, the actual data that eventually gave Dr. Higgs and François Englert their Nobel prize were collected by the Large Hadron Collider, arguably one of the largest technical projects that took thousands of scientists decades to design, build, and test.Continue reading “The World’s Most Sensitive Dark Matter Detector has Come Online”
Attempts to directly detect dark matter have come up empty. A team of physicists have proposed a brand new method: if dark matter exists in clumps that occasionally pass through the solar system, we may be able to detect their slight influence with ultra-sensitive gravitational waves detectors.Continue reading “Gravitational Wave Telescopes Could Detect Clumps of Dark Matter Drifting Through the Solar System”
Dark matter doesn’t really do much of anything in the present-day universe. But in the early days of the cosmos there may have been pockets of dark matter with high enough density that they provided a source of heat for newly forming stars. Welcome to the strange and wonderful world of “dark stars.”Continue reading “Dark Stars: The First Stars in the Universe Could Have Been Powered by Annihilating Dark Matter”
A team of astronomers studied two nearby globular clusters, 47 Tucanae and Omega Centauri, searching for signals produced by annihilating dark matter. Those the searches turned up empty, they weren’t a failure. The lack of a detection placed strict upper limits on the mass of the hypothetical dark matter particle.Continue reading “Could we Detect Dark Matter’s Annihilation Within Globular Clusters?”
If dark matter is out there, and it certainly seems to be, then what could it possibly be? That is perhaps the biggest mystery of dark matter. The only known particles that match the requirement of having mass and not interacting strongly with light are neutrinos. But neutrinos have low mass and zip through the cosmos at nearly the speed of light. They are a form of “hot” dark matter, so they don’t match the observed data that require dark matter to be “cold.” With neutrinos ruled out, cosmologists look toward various hypothetical particles we haven’t discovered, and perhaps the most popular of these are known as axions.Continue reading “If Axions are Dark Matter, we've got new Hints About Where to Look for Them”
In their pursuit of understanding cosmic evolution, scientists rely on a two-pronged approach. Using advanced instruments, astronomical surveys attempt to look farther and farther into space (and back in time) to study the earliest periods of the Universe. At the same time, scientists create simulations that attempt to model how the Universe has evolved based on our understanding of physics. When the two match, astrophysicists and cosmologists know they are on the right track!
In recent years, increasingly-detailed simulations have been made using increasingly sophisticated supercomputers, which have yielded increasingly accurate results. Recently, an international team of researchers led by the University of Helsinki conducted the most accurate simulations to date. Known as SIBELIUS-DARK, these simulations accurately predicted the evolution of our corner of the cosmos from the Big Bang to the present day.Continue reading “A Detailed Simulation of the Universe Creates Structures Very Similar to the Milky Way and its Surroundings”
Dark matter has long been a mystery to astronomers, in no small part because it is so hard to measure directly. Its influence is plain when looking at its gravitational effects on objects such as far away galaxies, but measuring that influence directly has proved much trickier. But now, a team of scientists thinks they have a way to measure the influence of dark matter directly – all it would require is a specialized probe that sits really far away from Earth for a while.Continue reading “How Dark Matter Could Be Measured in the Solar System”
According to our current Cosmological models, the Universe began with a Big Bang roughly 13.8 billion years ago. During the earliest periods, the Universe was permeated by an opaque cloud of hot plasma, preventing atoms from forming. About 380,000 years later, the Universe began to cool and much of the energy generated by the Big Bang converted into light. This afterglow is now visible to astronomers as the Cosmic Microwave Background (CMB), first observed during the 1960s.
One peculiar characteristic about the CMB that attracted a lot of attention was the tiny fluctuations in temperature, which could provide information about the early Universe. In particular, there is a rather large spot in the CMB that is cooler than the surrounding afterglow, known as the CMB Cold Spot. After decades of studying the CMB’s temperature fluctuations, a team of scientists recently confirmed the existence of the largest cold spots in the CMB afterglow – the Eridanus Supervoid – might be the explanation for the CMB Cold Spot that astronomers have been looking for!Continue reading “Finally, an Explanation for the Cold Spot in the Cosmic Microwave Background”