This Hubble Space Telescope image shows the giant Galaxy Cluster MACS 1206. Embedded in the cluster are distorted images of distant background galaxies, seen as arc and smear features. This distortion is caused by the amount of dark matter in the cluster, whose gravity bends and magnifies light from distant galaxies. This effect, called gravitational lensing, allows astronomers to study distant galaxies, which would otherwise be very dizzy to look at. Many cluster galaxies are large enough to distort and expand distant sources. Is. The galaxies of the three stretches represent examples of such effects. In the upper right and bottom snapshots, two distant, blue galaxies, poured through the faભાગade, form redder cluster galaxies, rings, and multiple images of distant objects objects. The red flowers around the constellation on the upper left indicate the emission of hydrogen clouds from a single distant source. The source, seen four times due to the lensing, could be a tight galaxy. These blobs were detected by a multi-unit spectroscopic explorer (MUSE) at a very large telescope (VLT) at the European Southern Observatory in Chile. Blobs do not appear in Hubble images. The MACS J1206 is part of a cluster lensing and supernova survey with Hubble (CLASH) and one of three galaxy clusters of researchers studying with Hubble and VLT. Hubble Image is a combination of visual and infrared-light observations taken in 2011 by Advanced Camera for Survey and Wide Field Camera 3.
Credit: NASA, ESA, p. Natarajan (Yale University), g. Kamina (University of Groningen), m. Menegatti (IANF-serv Observatory Astrophysics and Space Science of Bologna), CALASH-VLT / Zooming teams; Acceptance: NASA, ESA, m. Postman (STScI), CLASH Team
Astronomers have discovered that there may be a missing ingredient in a cosmic recipe for how dark matter behaves.
Astronomers have discovered the difference between how dark matter should be distributed in galaxy clusters, and theoretical models of observations of dark matter grip on clusters.
Dark matter does not emit, absorb or reflect light. Its presence is known only by pulling gravity on a visible object in space. So, Dark Matter is just as elusive in Cheshire Cat of Wonderland as Alice – where you will see not only her anger (in the form of gravity), but also the animal.
One way astronomers can detect dark matter is by how its gravity distorts space, an effect called gravitational lensing.
Researchers have found that small concentrations of dark matter in clusters produce gravitational lensing effects that are 10 times stronger than expected. This evidence is based on unprecedented detailed observations made by many large galaxy clusters. NASANo. Hubble Space Telescope And the European Southern Observatory Very large telescope (VLT) in Chile.
Astronomers think a surprising detail has emerged from the way dark matter behaves. They found small, ga ense concentrations of dark matter that bend and amplify more intense light than expected. Credit: NASA’s Goddard Space Flight Center
Galaxy clusters, the largest structures in the universe made up of individual member galaxies, are the largest deposits of dark matter. They are not largely held together by the gravity of dark matter, individual cluster galaxies themselves are filled with dark matter. Dark matter in clusters is therefore distributed on both large and small scales.
“Galaxy clusters are ideal laboratories for understanding whether computer simulations of the universe reproduce what we know about dark matter and its interaction with luminous matter,” said the National Institute for Astrophysics and Science. Was. Bologna, Italy, lead author of the study.
“We’ve done a lot of careful testing in comparing the simulations and data of this study, and our matching isn’t wrong,” Menegetti added. “One possible root for this discrepancy is that we may lose some key physics in simulations.”
Priyamvada Natarajan Yale University In New Haven, Connecticut, one of the team’s senior theorists, added, “One of the characteristics of the real universe is that we don’t capture our current theoretical models in Dello. This may indicate a difference in our current understanding of the nature of dark matter and its properties, as these excellent data have allowed us to examine the detailed distribution of dark matter on tiny scales. “
The team’s paper will appear in the September 11 issue of the journal Science.
The distribution of dark matter in clusters is created by the effect of light bending, or the gravitational lensing effect, which they produce. The gravity of a dark object, like a funhouse mirror, amplifies and wraps light from distant backgrounds from objects, producing distortions and sometimes multiple images of the same distant galaxy. The higher the concentration of dark matter in the cluster, the more dramatic its light bending.
Hubble’s crisp images, along with VLT’s Spectra, helped the team create an accurate, high-fidelity dark-matter map. They identified dozens of multiplied image, lens, background galaxies. By measuring lensing distortions, astronomers can detect the amount and distribution of dark matter.
The three key galaxy clusters used in the analysis, MACS J1206.2-0847, MACS J0416.1-2403, and Able S1063, were part of two Hubble surveys: Frontier Fields and Cluster Lensing and Supernova Survey (CALSH) programs with Hubble.
To the team’s surprise, Hubble images also revealed small-scale arcs and distorted images, with large-scale lens distortions in the main body of each cluster, where the largest galaxies reside.
The researchers believe that the embedded lens is produced by the gravity of the ga ense concentration of the dark matter associated with the individual cluster galaxies. The distribution of dark matter in the interior regions of individual galaxies is known to increase the overall lensing effect of the cluster.
Follow-up spectroscopic observations to measure the velocity of stars orbiting within multiple galaxies of the cluster, the study added. “Based on our spectroscopic study, we were able to associate galaxies with each cluster and estimate their distances,” said Pierro Rosati, a member of the team at the University of Ferrara in Italy.
“The motion of the stars gave us an estimate of the mass of each galaxy, including the amount of dark matter,” added Pietro Bergamini, a member of the IAANF-serv observatory Astrophysics and Space Science team in Bologna, Italy.
The team compared dark-matter maps with samples of simulated galaxy clusters with similar ones, located at approximately the same distance as the observation clusters. Clusters of computer simulations do not show the same level of dark-matter concentration on a small scale – scales associated with individual cluster galaxies as seen in the universe.
The team will look forward to continuing the stress-testing of the standard dark-matter model for its interesting nature below.
NASA’s Nancy Grace Roman Space Telescope will be able to detect even more distant galaxies by gravitational lensing through large galaxy clusters. Observations will expand the sample of clusters that astronomers can analyze to further test dark-matter models.
References: “Large scale small-scale gravitational lenses found in galaxy clusters” Benton Metalfe, Elena Rasiana, Stena, Francisco Calura, Claudio Grillo, Amta Mercurio and Eros Vanzella, 11 September 2020, Science.
DOI: 10.1126 / science.x5164
The Hubble Space Telescope is an international collaboration project between NASA and the ESA (European Space Agency). NASA’s Goddard Space Flight Center operates a telescope in Greenbelt, Maryland. The Space Telescope Science Institute (STSCI) operates Hubble Science in Baltimore. STSCI for NASA by the Universities Universities Research Society for Astronomy in Washington DC.
