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TOPIC: CBR
Blobrana


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Posts: 131433
Date:
WMAP Results
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Scientists peering back to the oldest light in the universe have new evidence to support the concept of inflation. The concept poses the universe expanded many trillion times its size in less than a trillionth of a second at the outset of the big bang.

This finding, made with the Wilkinson Microwave Anisotropy Probe (WMAP), is based on three years of continuous observations of the cosmic microwave background (CMB), the afterglow light produced when the universe was less than a million years old.
WMAP polarisation data allow scientists to discriminate between competing models of inflation for the first time. This is a milestone in cosmology.

"We can now distinguish between different versions of what happened within the first trillionth of a second of the universe. The longer WMAP observes, the more it reveals about how our universe grew from microscopic quantum fluctuations to the vast expanses of stars and galaxies we see today" - Charles Bennett, WMAP Principal Investigator, of the Johns Hopkins University in Baltimore.

Previous WMAP results focused on the temperature variations of this light, which provided an accurate age of the universe and insights into its geometry and composition. The new WMAP observations give not only a more detailed temperature map, but also the first full-sky map of the polarisation of the CMB. This major breakthrough will enable scientists to obtain much deeper insight into what happened within the first trillionth of a second of the universe.

The WMAP results have been submitted to the Astrophysical Journal and are posted at
http://wmap.gsfc.nasa.gov/results

Big bang physics describes how matter and energy developed over the last 13.7 billion years. WMAP's observation of the blanket of cool microwave radiation that permeates the universe shows patterns that mark the seeds of what grew into stars and galaxies. The patterns are tiny temperature differences within this extraordinarily uniform light. WMAP discerns temperature fluctuations at levels finer than a millionth of a degree.
WMAP can resolve features in the cosmic microwave background based on polarisation, or the way light is changed by the environment through which it passes. For example, sunlight reflecting off of a shiny object is polarised. Comparing the brightness of broad features to compact features in the microwave background, or afterglow light, helps tell the story of the infant universe. One long-held prediction was the brightness would be the same for features of all sizes. In contrast, the simplest versions of inflation predict the relative brightness decreases as the features get small, a trend seen in the new data.

"This is brand new territory. The polarisation data will become stronger as WMAP continues to observe the microwave background. WMAP's new results heighten the urgency of seeking out inflation's gravitational wave sign. If gravitational waves are seen in future measurements, that would be solid evidence for inflation" - Lyman Page, WMAP team member, Princeton University in Princeton, N.J.

With a richer temperature map and the new polarisation map, WMAP data favour the simplest versions of inflation. Generically, inflation posits that, at the outset of the big bang, quantum fluctuations - short-lived bursts of energy at the subatomic level - were converted by the rapid inflationary expansion into fluctuations of matter that ultimately enabled stars and galaxies to form. The simplest versions of inflation predict that the largest-sized fluctuations will also be the strongest.
The new results from WMAP favour this signature.
Inflation theory predicts that these same fluctuations also produced primordial gravitational waves whose distortion of space-time leaves a signature in the CMB polarisation. This will be an important goal of future CMB measurements which, if found, would provide a stunning confirmation of inflation.

"Inflation was an amazing concept when it was first proposed 25 years ago, and now we can support it with real data" - Gary Hinshaw, WMAP team member, NASA's Goddard Space Flight Center in Greenbelt, Md.

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Blobrana


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Posts: 131433
Date:
IceCube
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Hoping to unlock the mysteries of black holes and the Big Bang, a team of scientists from Japan and seven other countries has apparently detected its first neutrinos in a multiyear project underway in Antarctica.
The project, dubbed "IceCube," was launched in 2002, but only detected its first neutrinos on January 29, recording the faint flashes of light given off by the particles when they interact with electrons in water molecules.

According to team member Shigeru Yoshida, a cosmic-ray physics professor at Chiba University, this was the first time neutrinos had been captured in a natural environment outside a laboratory, but he cautioned that the results still needed to be studied and confirmed.

Neutrinos are subatomic particles with almost no mass and no electrical charge that are associated with radioactive decay. They so rarely interact with matter that they can typically pass entirely through the Earth unobstructed.
Scientists want to study the elusive particles because they may hold the key to understanding the explosion of super-massive stars, known as supernovae.
They also may hold secrets to other distant celestial objects, as they are thought to remain relatively intact during their travel through space.
But detecting neutrinos is tricky. It requires specialised equipment deep underground — shielded by heavy layers of rock from constant infiltration by cosmic rays, which may interfere with detection.

The IceCube project uses holes dug 2,500 meters into ice near the South Pole.
By using the vast Antarctic ice cap as a shield against cosmic rays, the team avoids the often prohibitive costs of building a specialized water tank, which is part of the conventional design for such experiments.

"If neutrinos were obtained this way, it would signal a new breakthrough in the study of the formation of the cosmos" - Shigeru Machida, honorary professor of elementary particle theory at Kyoto University, who is not involved in the project.

The Antarctic project is important because it should allow scientists to study where in space the neutrinos are coming from and how strongly they bombard Earth.
The team has placed 540 detectors in the ice so far — about 10 percent of the planned total of 4,800 to be installed over the next five years.
Joining the 30 billion yen (US$254.2 million; euro213.6 million) project are scientists from the United States, Britain, Germany, Sweden, Belgium, the Netherlands, New Zealand and Japan.
When complete, the IceCube project, located near the Amundsen-Scott South Pole Station, will be the world's largest neutrino detector.
The plan calls for building an observatory 1 cubic kilometre in size by 2010, about 20,000 times the capacity of the Super Kamiokande neutrino detector in central Japan.
The increased size will make the Antarctic detector much more sensitive.

Japanese scientist Masatoshi Koshiba won the 2002 Nobel Prize in physics for his work at the Super Kamiokande detector, which discovered neutrinos coming from distant supernova explosions.

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Blobrana


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Posts: 131433
Date:
Cosmic Infrared Background
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The sources of the Cosmic Infrared Background
Authors: G. Lagache (1), H. Dole (1), J.-L. Puget (1) ((1) Institut d'Astrophysique Spatiale, Orsay, France)

The discovery of the Cosmic Infrared Background (CIB) in 1996, together with recent cosmological surveys from the mid-infrared to the millimetre have revolutionized our view of star formation at high redshifts.
It has become clear, in the last decade, that a population of galaxies that radiate most of their power in the far-infrared (the so-called "infrared galaxies") contributes an important part of the whole galaxy build-up in the Universe.
Since 1996, detailed investigations of the high-redshift infrared galaxies have resulted in the spectacular progress reviewed in this paper.
Among others, The researchers emphasize a new Spitzer result based on a Far-IR stacking analysis of mid-IR sources.

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Blobrana


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Posts: 131433
Date:
IceCube
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The distribution of ancient neutrinos may eliminate some of the most promising theories linking gravity and quantum mechanics, according to a theoretical analysis put forth at the Perimeter Institute in Canada. Many physicists believe that combining gravity and quantum mechanics into a single theory is one of the most important problems in science today.
Leading attempts to create a unified theory of gravity and quantum mechanics, such as string theory and loop quantum gravity, make sense in a universe in which gravity is subordinate to the laws of quantum mechanics. However, problems with these sorts of theories have led some to propose that gravity and quantum mechanics are equal contributors to the final unified theory.

According to this hypothesis, gravity breaks the quantum nature of objects. The heavier the object, the quicker gravity leads to the breakdown; that is one reason that large objects, such as baseballs, obey the classical physics of Newton, while light objects such as electrons and other particles obey the counterintuitive laws of quantum mechanics. The new research suggests that this idea can be tested using neutrinos created in the early universe.

If gravity breaks down the quantum nature of neutrinos, this should be evident in ratios of the types of neutrinos detected at next generation neutrino experiments such as IceCube, a one cubic kilometre neutrino detector currently being built beneath the ice of Antarctica.

Such a result would require physicists to rethink popular theories including string theory and quantum loop gravity. It would also mean that the physics of the early universe was fundamentally different than it is today.

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Blobrana


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Posts: 131433
Date:
RE: CBR
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Recent results from AMANDA-II, an operating neutrino telescope located at the South Pole, are presented; including the examination of the diffuse neutrino flux, permanent and transient point source analyses, and indirect dark matter searches.



A brief outlook on the IceCube neutrino telescope currently under construction at the South Pole is also given.

Rad more (PDF)

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Blobrana


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Posts: 131433
Date:
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Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the centre of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of galaxies. The Local Group falls toward the Virgo Cluster of Galaxies. But these speeds are less than the speed that all of these objects together move relative to the cosmic microwave background radiation (CMBR).



In this all-sky map, radiation in the Earth's direction of motion appears blue shifted and hence hotter, while radiation on the opposite side of the sky is red shifted and colder.
The map indicates that the Local Group moves at about 600 kilometres per second relative to this primordial radiation. This high speed was initially unexpected and its magnitude is still unexplained. Why are we moving so fast? What is out there?




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Blobrana


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Posts: 131433
Date:
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20th April 2005

Cool spaces in the cosmic microwave background, thought to be the 'birthmarks' of galaxies and clusters of galaxies, should be bigger, according to new analysis of satellite data by scientists at The University of Alabama in Huntsville.
This new analysis suggests that there is enough matter in the universe to bend light and other radiation as it travels through space, a finding that might deflate the current standard model of inflationary cosmology (how the universe is expanding and how much mass exists in that universe).


Expand

Analysis of data from the Wilkinson Microwave Anisotropy Probe (WMAP) concluded that space is flat, or Euclidian, instead of being curved.

"But that analysis was flawed because it didn't take into account the clumpiness of the universe nearest to observers on Earth. The data were misinterpreted because the near universe isn't smooth."

The "flat universe" analysis of the WMAP data was done based on the incorrect assumption that the distribution of matter in the universe is as uniform now as it was in the cloud of hot gases that existed shortly after the Big Bang.

"It turns out that when you do the math you find that in the near universe, most of the microwaves go through the empty void and never go through a galaxy, so they diverge. These bundles of microwaves aren't going through enough gravity to hold them together."
This means the cool spots in the microwave background look smaller to WMAP than they actually were.
The bottom line then is that the earlier analysis undersized the overall area of an average microwave background cool spot by approximately ten percent.
"This means the true size of these cool regions must be bigger than we would see in Euclidian space, so the true density of the universe must be super-critical. The universe will be curved and we will be back in Einstein space."


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