Using a powerful new instrument at the South Pole, a team of cosmologists has produced the most detailed images of the early Universe ever recorded. The research team, which was funded by the National Science Foundation (NSF), has made public their measurements of subtle temperature differences in the Cosmic Microwave Background (CMB) radiation. The CMB is the remnant radiation that escaped from the rapidly cooling Universe about 400,000 years after the Big Bang. Images of the CMB provide researchers with a snapshot of the Universe in its infancy, and can be used to place strong constraints on its constituents and structure. The new results provide additional evidence to support the currently favored model of the Universe in which 30 percent of all energy is a strange form of dark matter that doesnt interact with light and 65 percent is in an even stranger form of dark energy that appears to be causing the expansion of the Universe to accelerate. Only the remaining five percent of the energy in the Universe takes the form of familiar matter like that which makes up planets and stars.
The researchers developed a sensitive new instrument, the Arcminute Cosmology Bolometer Array Receiver (ACBAR), to produce high-resolution images of the CMB. ACBARs detailed images reveal the seeds that grew to form the largest structures seen in the Universe today. These results add to the description of the early Universe provided by several previous ground-, balloon- and space-based experiments. Previous to the ACBAR results, the most sensitive, fine angular scale CMB measurements were produced by the NSF-funded Cosmic Background Investigator (CBI) experiment observing from a mountaintop in Chile.
William Holzapfel, of the University of California at Berkeley and ACBAR co-principal investigator, said it is significant that the new ACBAR results agree with those published by the CBI team despite the very different instruments, observing strategies, analysis techniques, and sources of foreground emission for the two experiments. He added that the new data provide a more rigorous test of the consistency of the new ACBAR results with theoretical predictions.
"It is amazing how precisely our theories can explain the behavior of the Universe when we know so little about the dark matter and dark energy that comprise 95 percent of it," said Holzapfel.
The dark energy inferred from the ACBAR observations may be responsible for the accelerating expansion of the Universe. "It is compelling that we find, in the ancient history of the Universe, evidence for the same dark energy that supernova observations find more recently," said Jeffrey Peterson of Carnegie Mellon University.
The construction of the ACBAR instrument and observations at the South Pole were carried out by a team of researchers from the University of California, Berkeley, Case Western Reserve University, Carnegie Mellon University, the California Institute of Technology, Jet Propulsion Laboratory (JPL), and Cardiff University in the United Kingdom. Principle investigators Holzapfel and John Ruhl at Case Western led the effort, which built and deployed the instrument in only two years.
ACBAR is specifically designed to take advantage of the unique capabilities of the 2.1-meter Viper telescope, built primarily by Jeff Peterson and collaborators at Carnegie Mellon and installed by NSF and its South Pole Station in Antarctica. The receiver is an array of 16 detectors built by Cal Tech and the JPL that create images of the sky in 3-millimeter wavelength bands near the peak in the brightness of the CMB. In order to reach the maximum possible sensitivity, the ACBAR detectors are cooled to two-tenths of a degree above absolute zero, or about -273 degrees Celsius (-459 Fahrenheit). ACBAR has just completed its second season of observations at the South Pole. Researcher Mathew Newcomb kept the telescope observing continuously during the six month-long austral winter, despite temperatures plunging below -73 degrees Celsius (-100 Fahrenheit).
The construction of ACBAR and Viper was funded as part of the NSF Center for Astrophysical Research in Antarctica. The U.S. Antarctic Program provides continuing support for telescope maintenance, observations, and data analysis. NSFs Amundsen Scott South Pole Station is ideally suited for astronomy, especially observations of the CMB. The station is located at an altitude of approximately 3,000 meters (10,000 feet), atop the Antarctic ice sheet. Water vapor is the principal cause of atmospheric absorption in broad portions of the electromagnetic spectrum from near infrared to microwave wavelengths. The thin atmosphere above the station is extremely cold and contains almost no water vapor. "Our atmosphere may be essential to life on Earth," said Ruhl, "but wed love to get rid of it. For our observations, the South Pole is as close as you can get to space while having your feet planted firmly on the ground."
Papers describing the ACBAR CMB angular power spectrum and the constraints it places on cosmological parameters have been submitted to the Astrophysical Journal for publication.
Leslie Fink, National Science Foundation
Leslie Fink | NSF
Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas
22.09.2017 | Forschungszentrum MATHEON ECMath
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy