The images and our best computer models don't agree.
A trio of intriguing galaxy clusters<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQzNDA0OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNTkzNzUyOH0.0IRzkzvKsmPEHV-v1dqM1JIPhgE2W-UHx0COuB0qQnA/img.jpg?width=980" id="d69be" class="rm-shortcode" data-rm-shortcode-id="2d2664d9174369e0a06540cb3a3a9079" data-rm-shortcode-name="rebelmouse-image" />
The three galaxy clusters imaged for the study
Mapping dark matter<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="d904b585c806752f261e1215014691a6"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/fO0jO_a9uLA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>The assumption has been that the greater the lensing effect, the higher the concentration of dark matter.</p><p>As scientists analyzed the clusters' large-scale lensing — the massive arc and elongation visual effects produced by dark matter — they noticed areas of smaller-scale lensing within that larger distortion. The scientists interpret these as concentrations of dark matter within individual galaxies inside the clusters.</p><p>The researchers used spectrographic data from the VLT to determine the mass of these smaller lenses. <a href="https://www.oas.inaf.it/en/user/pietro.bergamini/" target="_blank" rel="noopener noreferrer">Pietro Bergamini</a> of the INAF-Observatory of Astrophysics and Space Science in Bologna, Italy explains, "The speed of the stars gave us an estimate of each individual galaxy's mass, including the amount of dark matter." The leader of the spectrographic aspect of the study was <a href="http://docente.unife.it/docenti-en/piero.rosati1/curriculum?set_language=en" target="_blank">Piero Rosati</a> of the Università degli Studi di Ferrara, Italy who recalls, "the data from Hubble and the VLT provided excellent synergy. We were able to associate the galaxies with each cluster and estimate their distances." </p><p>This work allowed the team to develop a thoroughly calibrated, high-resolution map of dark matter concentrations throughout the three clusters.</p>
But the models say...<p>However, when the researchers compared their map to the concentrations of dark matter computer models predicted for galaxies bearing the same general characteristics, something was <em>way</em> off. Some small-scale areas of the map had 10 times the amount of lensing — and presumably 10 times the amount of dark matter — than the model predicted.</p><p>"The results of these analyses further demonstrate how observations and numerical simulations go hand in hand," notes one team member, <a href="https://nena12276.wixsite.com/elenarasia" target="_blank">Elena Rasia</a> of the INAF-Astronomical Observatory of Trieste, Italy. Another, <a href="http://adlibitum.oats.inaf.it/borgani/" target="_blank" rel="noopener noreferrer">Stefano Borgani</a> of the Università degli Studi di Trieste, Italy, adds that "with advanced cosmological simulations, we can match the quality of observations analyzed in our paper, permitting detailed comparisons like never before."</p><p>"We have done a lot of testing of the data in this study," Meneghetti says, "and we are sure that this mismatch indicates that some physical ingredient is missing either from the simulations or from our understanding of the nature of dark matter." <a href="https://physics.yale.edu/people/priyamvada-natarajan" target="_blank">Priyamvada Natarajan</a> of Yale University in Connecticut agrees: "There's a feature of the real Universe that we are simply not capturing in our current theoretical models."</p><p>Given that any theory in science lasts only until a better one comes along, Natarajan views the discrepancy as an opportunity, saying, "this could signal a gap in our current understanding of the nature of dark matter and its properties, as these exquisite data have permitted us to probe the detailed distribution of dark matter on the smallest scales."</p><p>At this point, it's unclear exactly what the conflict signifies. Do these smaller areas have unexpectedly high concentrations of dark matter? Or can dark matter, under certain currently unknown conditions, produce a tenfold increase in lensing beyond what we've been expecting, breaking the assumption that more lensing means more dark matter?</p><p>Obviously, the scientific community has barely begun to understand this mystery.</p>
What we know about black holes is both fascinating and scary.
- When it comes to black holes, science simultaneously knows so much and so little, which is why they are so fascinating. Focusing on what we do know, this group of astronomers, educators, and physicists share some of the most incredible facts about the powerful and mysterious objects.
- A black hole is so massive that light (and anything else it swallows) can't escape, says Bill Nye. You can't see a black hole, theoretical physicists Michio Kaku and Christophe Galfard explain, because it is too dark. What you can see, however, is the distortion of light around it caused by its extreme gravity.
- Explaining one unsettling concept from astrophysics called spaghettification, astronomer Michelle Thaller says that "If you got close to a black hole there would be tides over your body that small that would rip you apart into basically a strand of spaghetti that would fall down the black hole."
Tyson dives into the search for alien life, dark matter, and the physics of football.
- Astrophysicist Neil deGrasse Tyson joins us to talk about one of our favorite subjects: space.
- In the three-chaptered video, Tyson speaks about the search for alien life inside and outside of the Goldilocks Zone, why the term "dark matter" should really be called "dark gravity," and how the rotation of the Earth may have been the deciding factor in a football game.
- These fascinating space facts, as well as others shared in Tyson's books, make it easier for everyone to grasp complex ideas that are literally out of this world.
The planet that we are searching for is a little bit smaller and closer than we originally thought.
- Years ago, California Institute of Technology professor Konstantin Batygin was inspired to embark on a journey of discovering what lurked beyond Neptune. What he and his collaborator discovered was a strange field of debris.
- This field of debris exhibited a clustering of orbits, and something was keeping these orbits confined. The only plausible source would be the gravitational pull of an extra planet—Planet Nine.
- While Planet Nine hasn't been found directly, the pieces of the puzzle are coming together. And Batygin is confident we'll return to a nine-planet solar system within the next decade.
Have we already found dark matter? It may be hiding in existing data, says a study.
- A new study proposes to look for dark matter during the process of scattering.
- The scientists think dark matter indicators could be hiding in existing data.
- The researchers aim to adapt current experiments to find the elusive particles.
Photomultiplier tube arrays prepared for the LUX-ZEPLIN experiment. Sanford Underground Research Facility in Lead, South Dakota.
Credit: Matt Kapust/SURF