The radiation residue from the Big Bang, misshaped by dark matter 12 billion years back. Credit: Reiko Matsushita
Researchers examined the nature of dark matter surrounding galaxies viewed as they were 12 billion years earlier, billions of years even more back in time than ever previously. Their findings use the alluring possibility that the fundamental rules of cosmology might differ when analyzing the early history of our universe. The cooperation was led by scientists at Nagoya University in Japan and the findings were published today (August 1) in the journal Physical Review Letters.
Seeing something that occurred such a long period of time ago is tough. Due to the fact that of the speed of light is limited, we see distant galaxies not as they are today, but as they were billions of years earlier. However even more difficult is observing dark matter, which does not discharge light.
Consider a remote source galaxy, even further away than the target galaxy whose dark matter one desires to examine. As the light from the source galaxy takes a trip through this distortion in spacetime, it bends, altering the obvious shape of the galaxy. Astronomers can measure the quantity of dark matter around the foreground galaxy (the “lens” galaxy) from the distortion.
After I provided a talk about a big remote galaxy sample, Hironao came to me and stated it may be possible to look at dark matter around these galaxies with the CMB.”
Galaxy clusters make up 100-1000 galaxies bound by gravity with large amounts of dark matter.
Consider a distant source galaxy, even further away than the target galaxy whose dark matter one wants to examine. As anticipated by Einsteins theory of general relativity, the gravitational attraction of the foreground galaxy, including its dark matter, distorts the surrounding area and time. As the light from the source galaxy travels through this distortion in spacetime, it flexes, altering the evident shape of the galaxy. The higher the quantity of dark matter, the higher the resulting distortion. Astronomers can determine the amount of dark matter around the foreground galaxy (the “lens” galaxy) from the distortion.
In the inmost reaches of the universe, the galaxies are incredibly faint. Because the lensing distortion is subtle and difficult to spot in most cases, many background galaxies are needed to spot the signal.
Most previous studies have stayed stuck at the exact same limitations. Unable to spot enough far-off source galaxies to determine the distortion, they might just analyze dark matter from no greater than 8-10 billion years earlier. These constraints exposed the concern of the distribution of dark matter between this time and 13.7 billion years back, around the beginning of our universe.
To get rid of these difficulties and observe dark matter from the farthest reaches of deep space, a group of researchers led by Hironao Miyatake from Nagoya University, in collaboration with the University of Tokyo, the National Astronomical Observatory of Japan, and Princeton University, used a various source of background light, the microwaves launched from the Big Bang itself.
Using data from the observations of the Subaru Hyper Suprime-Cam Survey (HSC), the group identified 1.5 million lens galaxies utilizing visible light, selected to be seen 12 billion years earlier.
Next, to get rid of the lack of galaxy light even further away, they employed microwaves from the cosmic microwave background (CMB), the radiation residue from the Big Bang. Using microwaves observed by the European Space Agencys Planck satellite, the team measured how the dark matter around the lens galaxies distorted the microwaves.
No one realized we could do this. After I offered a talk about a large remote galaxy sample, Hironao came to me and stated it may be possible to look at dark matter around these galaxies with the CMB.”
” Most scientists utilize source galaxies to determine dark matter circulation from the present to eight billion years back,” added Assistant Professor Yuichi Harikane of the Institute for Cosmic Ray Research, University of Tokyo. “However, we might look further back into the past since we utilized the more far-off CMB to determine dark matter. For the very first time, we were measuring dark matter from nearly the earliest moments of the universe.”
After a preliminary analysis, the scientists soon realized that they had a large sufficient sample to find the distribution of dark matter. Combining the large far-off galaxy sample and the lensing distortions in CMB, they found dark matter even further back in time, from 12 billion years ago. This is just 1.7 billion years after the start of deep space, and therefore these galaxies are seen right after they initially formed.
“12 billion years back, things were extremely various. Galaxy clusters comprise 100-1000 galaxies bound by gravity with big amounts of dark matter.
” This result offers an extremely consistent image of galaxies and their advancement, as well as the dark matter around galaxies, and how this image evolves with time,” stated Neta Bahcall, Eugene Higgins Professor of Astronomy, professor of astrophysical sciences, and director of undergraduate studies at Princeton University.
According to the standard theory of cosmology, the Lambda-CDM model, subtle variations in the CMB type pools of densely packed matter by attracting surrounding matter through gravity. This produces inhomogeneous clumps that form stars and galaxies in these thick regions.
Miyatake is enthusiastic about the possibilities. “Our finding is still unpredictable,” he said. “But if it is true, it would recommend that the entire design is flawed as you go further back in time. This is exciting because if the outcome holds after the unpredictabilities are reduced, it might suggest an improvement of the design that might supply insight into the nature of dark matter itself.”
” At this point, we will attempt to get much better data to see if the Lambda-CDM design is in fact able to discuss the observations that we have in deep space,” said Andrés Plazas Malagón, associate research study scholar at Princeton University. “And the effect may be that we need to review the assumptions that entered into this design.”
” One of the strengths of taking a look at the universe utilizing large-scale surveys, such as the ones utilized in this research, is that you can study everything that you see in the resulting images, from nearby asteroids in our solar system to the most distant galaxies from the early universe. You can utilize the very same data to explore a great deal of new concerns,” stated Michael Strauss, professor and chair of the Department of Astrophysical Sciences at Princeton University.
The next step will be to analyze the entire data set, which ought to enable for a more accurate measurement of the dark matter circulation. In the future, the group expects to use a sophisticated data set like the Vera C. Rubin Observatorys Legacy Survey of Space and Time (LSST) to explore more of the earliest parts of space. “I do not see any reason we couldnt see the dark matter distribution 13 billion years ago next.”
Reference: “First Identification of a CMB Lensing Signal Produced by 1.5 Million Galaxies at z ~ 4: Constraints on Matter Density Fluctuations at High Redshift” by Hironao Miyatake, Yuichi Harikane, Masami Ouchi, Yoshiaki Ono, Nanaka Yamamoto, Atsushi J. Nishizawa, Neta Bahcall, Satoshi Miyazaki and Andrés A. Plazas Malagón, 1 August 2022, Physical Review Letters.DOI: 10.1103/ PhysRevLett.129.061301.
” It was an insane idea. Nobody understood we might do this.”– Professor Masami Ouchi
