Research by the Atacama Cosmology Telescope collaboration has culminated in a significant breakthrough in understanding the evolution of the universe.
For millennia, humans have been fascinated by the mysteries of the cosmos.
Unlike ancient philosophers imagining the universe’s origins, modern cosmologists use quantitative tools to gain insights into its evolution and structure. Modern cosmology dates back to the early 20th century, with the development of Albert Einstein’s theory of general relativity.
Now, researchers from the Atacama Cosmology Telescope (ACT) collaboration have submitted a set of papers to The Astrophysical Journal featuring a groundbreaking new map of dark matter distributed across a quarter of the sky, extending deep into the cosmos, that confirms Einstein’s theory of how massive structures grow and bend light over the 14-billion-year life span of the universe.
The new map uses light from the cosmic microwave background (CMB) essentially as a backlight to silhouette all the matter between us and the Big Bang.
“It’s a bit like silhouetting, but instead of just having black in the silhouette, you have texture and lumps of dark matter, as if the light were streaming through a fabric curtain that had lots of knots and bumps in it,” said Suzanne Staggs, director of ACT and Henry DeWolf Smyth Professor of Physics at Princeton University. “The famous blue and yellow CMB image [from 2003] is a snapshot of what the universe was like in a single epoch, about 13 billion years ago, and now this is giving us the information about all the epochs since.”
“It’s a thrill to be able to see the invisible, to uncover this scaffold of dark matter that holds our visible star-filled galaxies,” said Jo Dunkley, a professor of physics and astrophysical sciences, who leads the analysis for ACT. “In this new image, we can see directly the invisible cosmic web of dark matter that surrounds and connects galaxies.”
“Usually, astronomers can only measure light, so we see how galaxies are distributed across the universe; these observations reveal the distribution of mass, so primarily show how the dark matter is distributed through our universe,” said David Spergel, Princeton’s Charles A. Young Professor of Astronomy on the Class of 1897 Foundation, Emeritus, and the president of the Simons Foundation.
“We have mapped the invisible dark matter distribution across the sky, and it is just as our theories predict,” said co-author Blake Sherwin, a 2013 Ph.D. alumnus of Princeton and a professor of cosmology at the University of Cambridge, where he leads a large group of ACT researchers. “This is stunning evidence that we understand the story of how structure in our universe formed over billions of years, from just after the Big Bang to today.’
He added: “Remarkably, 80% of the mass in the universe is invisible. By mapping the dark matter distribution across the sky to the largest distances, our ACT lensing measurements allow us to clearly see this invisible world.”
“When we proposed this experiment in 2003, we had no idea the full extent of information that could be extracted from our telescope,” said Mark Devlin, the Reese Flower Professor of Astronomy at the University of Pennsylvania and the deputy director of ACT, who was a Princeton postdoc from 1994-1995. “We owe this to the cleverness of the theorists, the many people who built new instruments to make our telescope more sensitive, and the new analysis techniques our team came up with.” This includes a sophisticated new model of ACT’s instrument noise by Princeton graduate student Zach Atkins.
Despite making up most of the universe, dark matter has been hard to detect because it doesn’t interact with light or other forms of electromagnetic radiation. As far as we know, dark matter only interacts with gravity.
To track it down, the more than 160 collaborators who have built and gathered data from the National Science Foundation’s Atacama Cosmology Telescope in the high Chilean Andes observed light emanating following the dawn of the universe’s formation, the Big Bang — when the universe was only 380,000 years old. Cosmologists often refer to this diffuse CMB light that fills our entire universe as the “baby picture of the universe.”
The team tracked how the gravitational pull of massive dark matter structures can warp the CMB on its 14-billion-year journey to us, just as antique, lumpy windows bend and distort what we can see through them.
“We’ve made a new mass map using distortions of light left over from the Big Bang,” said Mathew Madhavacheril, a 2016-2018 Princeton postdoc who is the lead author of one of the papers and an assistant professor in physics and astronomy at the University of Pennsylvania. “Remarkably, it provides measurements that show that both the ‘lumpiness’ of the universe, and the rate at which it is growing after 14 billion years of evolution, are just what you’d expect from our standard model of cosmology based on Einstein’s theory of gravity.”
Sherwin added, “Our results also provide new insights into an ongoing debate some have called ‘The Crisis in Cosmology.’” This “crisis” stems from recent measurements that use a different background light, one emitted from stars in galaxies rather than the CMB. These have produced results that suggest the dark matter was not lumpy enough under the standard model of cosmology and led to concerns that the model may be broken. However, the ACT team’s latest results precisely assessed that the vast lumps seen in this image are the exact right size.
“While earlier studies pointed to cracks in the standard cosmological model, our findings provide new reassurance that our fundamental theory of the universe holds true,” said Frank Qu, lead author of one of the papers and a Cambridge graduate student as well as a former Princeton visiting researcher.
“The CMB is famous already for its unparalleled measurements of the primordial state of the universe, so these lensing maps, describing its subsequent evolution, are almost an embarrassment of riches,” said Staggs, whose team built the detectors that gathered this data over the past five years. “We now have a second, very primordial map of the universe. Instead of a ‘crisis,’ I think we have an extraordinary opportunity to use these different data sets together. Our map includes all of the dark matter, going back to the Big Bang, and the other maps are looking back about 9 billion years, giving us a layer that is much closer to us. We can compare the two to learn about the growth of structures in the universe. I think is going to turn out to be really interesting. That the two approaches are getting different measurements is fascinating.”
ACT, which operated for 15 years, was decommissioned in September 2022. Nevertheless, more papers presenting results from the final set of observations are expected to be submitted soon, and the Simons Observatory will conduct future observations at the same site, with a new telescope slated to begin operations in 2024. This new instrument will be capable of mapping the sky almost 10 times faster than ACT.
Of the co-authors on the ACT team’s series of papers, 56 are or have been Princeton researchers. More than 20 scientists who were junior researchers on ACT while at Princeton are now faculty or staff scientists themselves. Lyman Page, Princeton’s James S. McDonnell Distinguished University Professor in Physics, was the former principal investigator of ACT.
This research will be presented at “Future Science with CMB x LSS,” a conference running from April 10-14 at Yukawa Institute for Theoretical Physics, Kyoto University. The pre-print articles highlighted here will appear on the open-access arXiv.org. They have been submitted to the Astrophysical Journal. This work was supported by the U.S. National Science Foundation (AST-0408698, AST-0965625 and AST-1440226 for the ACT project, as well as awards PHY-0355328, PHY-0855887 and PHY-1214379), Princeton University, the University of Pennsylvania, and a Canada Foundation for Innovation award. Team members at the University of Cambridge were supported by the European Research Council.
It looks like an overly thick section reconstruction to me. A sufficiently expanded thin section reconstruction will predictably show regular notably round voids.
One has to realize it’s unrealistic to expect GR experts to ever admit DM is a theory error signal.
It’s a mass map…not a dark matter, nice try though.
how do you make a map of something not there it is like making a map of unicorns
I AM GROOT
The map is only part way. Dark matter is everywhere. Discovered it a yr ago , that’s all I have to say for now
There are images of dark matter effects in sections much thinner than covering the whole mess from the CMB onward as done here. The picture pieces here are the equivalent of showing an entire ham through a thicket when there already exist microscope slides of muscle slices from the same ham. Like I suggested before, uniform spherical voids are prevalent in sufficiently thin sections. It’s clear enough in the image I’ve seen that hard to avoid a notion that the dark matter “ham” has the most intensive case of trichinosis that could ever be imagined.
Given there is no such thing as “dark matter” (mass problems are caused by “red shift” error assumed to be distance, but is often “light dimming” from dust and other things between us and the target making the distance calculations erroneous) this map just proves how unbelievably STUPID scientists have become that they’ll do literally ANYTHING to push a narrative or get more money/funding. The truth doesn’t matter, just the money, grants and funding. It’s why no other hypothesis for Alzheimer’s Disease gets looked at but the one the majority “decided” is correct, despite little to no success in helping fight the problem in over a decade of wasted research and failed medications that make little or no actual difference (see also anti-depressant pills that do no work the way they said they do and probably don’t work at all beyond the placebo effect). $$$ Cha-ching. $$$$. Cha-ching.
Maybe some commenters here should study how dark matter maps are created.
I’ve also noticed that no one who criticizes cosmological redshift ever ever shows any sign of reading any relevant studies such as Shapiro et al using SN data.
In my long time of studying gravity and cosmology as a hobby it has become evident that most critics of the mainstream are simply about registering their religion, especially if it’s the lazy religion of everlastingly constant light speed in variable gravity. Collectively, with practically military-scale efficiency, internet denizens especially seem to enjoy creating fantastical crackpot parody characters to set the tone for all critics on the same internet page. Such people are simply all about constructing convenient pathetic lazybrain bases for ignoring all critics of the mainstream.
The most logical thought process seems to be “Hey I see a critic or two of my favorite uncle’s beautifully successful nepotism science theory, so I think I’ll impressively shade them all by pretending to be an especially thoughtless critic here.”
Dark Matter consists of Black Holes. They are finding more and more of them every day. They are the largest fragments from the Big Bank (Bomb) that fly faster than the smoke (stars).
A görbült térbenm egyenes vonalakkal határolt idomként elég fura.