̽��ֱ�� of Cambridge - Blake Sherwin

New findings that map the universe’s cosmic growth support Einstein’s theory of gravity

sc604 — Tue, 11 Apr 2023 14:00:00 +0000

̽��ֱ��findings, from the Atacama Cosmology Telescope collaboration involving researchers from the ̽��ֱ�� of Cambridge, provide further support to Einstein’s theory of general relativity, which has been the foundation of the standard model of cosmology for more than a century. ̽��ֱ��results offer new methods to demystify dark matter, the unseen mass thought to account for 85% of the matter in the universe.

For millennia, humans have been fascinated by the mysteries of the cosmos. From ancient civilisations such as the Babylonians, Greeks, and Egyptians to modern-day astronomers, the allure of the starry sky has inspired countless quests to unravel the secrets of the universe.

And although models that explain the cosmos have existed for centuries, the field of cosmology, where scientists use quantitative methods to understand the evolution and structure of the universe, is relatively new—having only formed in the early 20th century with the development of Albert Einstein’s theory of general relativity.

Now, a set of papers submitted to ̽��ֱ��Astrophysical Journal by researchers from the Atacama Cosmology Telescope (ACT) collaboration has produced a new image that reveals the most detailed map of matter distributed across a quarter of the entire sky, reaching deep into the cosmos. It confirms Einstein’s theory about how massive structures grow and bend light, with a test that spans the entire age of the universe.

“We have mapped the invisible dark matter across the sky to the largest distances, and clearly see features of this invisible world that are hundreds of millions of light-years across,” said co-author Professor Blake Sherwin from Cambridge’s Department of Applied Mathematics and Theoretical Physics, where he leads a group of ACT researchers. “It looks just as our theories predict.”

Although dark matter makes up a large chunk of the universe and shaped its evolution, it has remained 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 observe 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 light that fills our entire universe as the “baby picture of the universe,” but formally, it is known as the cosmic microwave background radiation (CMB).

̽��ֱ��team tracks how the gravitational pull of large, heavy structures including dark matter warps the CMB on its 14-billion year journey to us, like how a magnifying glass bends light as it passes through its lens.

“We’ve made a new mass map using distortions of light left over from the Big Bang,” said Mathew Madhavacheril from the ̽��ֱ�� of Pennsylvania, lead author of one of the papers. “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.”

“Our results also provide new insights into an ongoing debate some have called ‘ ̽��ֱ��Crisis in Cosmology’,” said Sherwin. 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 team’s latest results from ACT were able to precisely assess that the vast lumps seen in this image are the exact right size.

“When I first saw them, our measurements were in such good agreement with the underlying theory that it took me a moment to process the results,” said Cambridge PhD candidate Frank Qu, lead author of one of the new papers. “But we still don’t know what the dark matter is, so it will be interesting to see how this possible discrepancy between different measurements will be resolved.”

“ ̽��ֱ��CMB lensing data rivals more conventional surveys of the visible light from galaxies in their ability to trace the sum of what is out there,” said Suzanne Staggs from Princeton ̽��ֱ��, Director of ACT. “Together, the CMB lensing and the best optical surveys are clarifying the evolution of all the mass in the universe.”

“When we proposed this experiment in 2003, this measurement wasn’t even on our agenda; we had no idea the full extent of information that could be extracted from our telescope,” said Mark Devlin, from the ̽��ֱ�� of Pennsylvania, Deputy Director of ACT. “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.”

With ACT having been decommissioned in late 2022, further papers highlighting some of the other final results are slated for submission in the coming year. Observations will continue at the site with the Simons Observatory, including a new telescope due to begin in 2024 that can map the sky almost ten times faster.

̽��ֱ��pre-print articles highlighted in this release are available on act.princeton.edu and will appear on the open-access arXiv.org. They have been submitted to ̽��ֱ��Astrophysical Journal.

This work was supported by the U.S. National Science Foundation, Princeton ̽��ֱ��, the ̽��ֱ�� of Pennsylvania, and a Canada Foundation for Innovation award. Team members at the ̽��ֱ�� of Cambridge were supported by the European Research Council.

A new image reveals the most detailed map of dark matter distributed across a quarter of the entire sky, reaching deep into the cosmos.

We have mapped the invisible dark matter across the sky to the largest distances, and clearly see features of this invisible world that are hundreds of millions of light-years across

Blake Sherwin

ACT Collaboration

A new map of the dark matter made by the Atacama Cosmology Telescope. ̽��ֱ��orange regions show where there is more mass; purple where there is less.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Eight Cambridge researchers awarded major European starter grants

cjb250 — Tue, 03 Sep 2019 13:35:55 +0000

̽��ֱ��European Research Council (ERC) Starting Grants have been awarded to 408 researchers from across Europe. ̽��ֱ��awards will help individual researchers to build their own teams and conduct world-leading research across all disciplines, creating an estimated 2,500 jobs for postdoctoral fellows, PhD students and other staff at the host institutions.

̽��ֱ��successful Cambridge researchers are:

Roland Bauerschmidt - Renormalisation, dynamics, and hyperbolic symmetry
Quentin Berthet - Computational Trade-offs and Algorithms in Statistics
Felix Deschler - Twisted Perovskites: Control of Spin and Chirality in Highly-luminescent Metal-halide Perovskites
Lorenzo Di Michele - A DNA NANOtechology toolkit for artificial CELL design
Louise Hirst - Gliding epitaxy for inorganic space-power sheets
Sertac Sehlikoglu - Imaginative Landscapes of Islamist Politics Across the Balkan-to-Bengal Complex
Blake Sherwin - CMB Lensing at Sub-Percent Precision: A New Probe of Cosmology and Fundamental Physics
Margherita Turco - Human Placental Development and the Uterine Microenvironment

Commenting on the awards, Dr Peter Hedges, Head of the ̽��ֱ�� Research Office at the ̽��ֱ�� of Cambridge, said: “ ̽��ֱ��success of UK researchers, and in particular Cambridge researchers, demonstrates the world-leading position that our country holds in research and innovation. This is a position we have will have to fight hard to maintain in the face of competition from other nations across Europe, the USA and China.

“Six of our successful researchers are non-UK nationals, showing once again that Cambridge has the ability to attract the very best talent from around the world to carry out research at its world class facilities.”

̽��ֱ��ERC-funded research will be carried out in 24 countries, with institutions from Germany (73), the UK (64) and the Netherlands (53) to host the highest number of projects. ̽��ֱ��grants, worth in total €621 million (£560 million), are part of the EU Research and Innovation programme, Horizon 2020.

Carlos Moedas, European Commissioner for Research, Science and Innovation, said: “Researchers need freedom and support to follow their scientific curiosity if we are to find answers to the most difficult challenges of our age and our future. This is the strength of the grants that the EU provides through the European Research Council: an opportunity for outstanding scientists to pursue their most daring ideas.”

President of the ERC, Professor Jean-Pierre Bourguignon, added: “In this year’s ERC Starting Grant competition, early-career researchers of 51 nationalities are among the winners – a record. It reminds us that science knows no borders and that talent is to be found everywhere. It is essential that, for its future successful development, the European Union keeps attracting and supporting outstanding researchers from around the world. At the ERC we are proud to contribute to this goal by supporting some of the most daring creative scientific talent.”

Eight Cambridge researchers are among the latest recipients of European Union awards given to early-career researchers from over 50 countries.

Six of our successful researchers are non-UK nationals, showing once again that Cambridge has the ability to attract the very best talent from around the world to carry out research at its world class facilities

Peter Hedges

Géry PARENT

Naturally-occurring perovskite

Researcher profile: Dr Margherita Turco

Among this year’s successful awardees is Dr Margherita Turco from Cambridge’s Centre for Trophoblast Research (CTR).

Margherita began her career studying the development of embryos in domestic animals during her studies for Veterinary Biotechnology at the ̽��ֱ�� of Bologna, in Italy. During her PhD in Molecular Medicine at the European Institute of Oncology in Milano, she became interested in how early cell lineage decisions are made and began using various stem cells models to address this question.

This led Margherita to come to Cambridge in 2012 to carry out her postdoctoral work on human trophoblast stem cells at the CTR. Her goal is to understand how the human placenta grows and develops during pregnancy.

“ ̽��ֱ��placenta is a remarkable organ that is formed early in pregnancy. It plays the crucial role of nourishing and protecting the baby throughout its development before birth,” she says. However, there is a lot that can go wrong during this period.

“Complications occurring during pregnancy, such as pre-eclampsia, fetal growth restriction, stillbirth, miscarriage and premature birth, are principally due to defective placental function. These conditions, which collectively affect around one in five pregnancies, can pose a risk to both the baby and mother’s health. Understanding early placental development is the key to understanding successful pregnancy.”

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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