Subscribe free to our newsletters via your
. 24/7 Space News .


Subscribe free to our newsletters via your




















Cosmological Data Affected By An Unexpected Source Of Radiation In Interstellar Space

Dr. Gerrit Verschuur, a pioneer in the science of radio astronomy, has been studying the properties of the Milky Way using interstellar HI for almost 50 years. According to his recent work, it appears that many of the small-scale structures observed by WMAP are correlated with HI.
by Staff Writers
Memphis TN (SPX) Nov 13, 2007
The widely lauded discovery of small-scale structure in the cosmic microwave background may be seriously affected by a previously unidentified source of radio emission in our own Milky Way Galaxy. This is the conclusion arrived at by Dr. Gerrit Verschuur, Adjunct Professor of Physics at the University of Memphis. His work will be published in the December 10 issue of the Astrophysical Journal.

Verschuur was studying data from the first ever all-sky survey of interstellar neutral hydrogen (HI) when he noticed intriguing similarities to the structure observed by the Microwave Anisotropy Probe (WMAP) spacecraft.

WMAP was designed to detect faint variations in the cosmic microwave background, a pervasive signal left over from the Big Bang itself. This anisotropy may represent the first step in the structural evolution of the universe, a middle ground between the ultra-smooth cosmic microwave background and the clusters of galaxies that exist today.

The anisotropy detected with WMAP confirms a discovery made a decade earlier by the Cosmic Background Explorer (COBE) spacecraft. As a result, the COBE scientists won the 2006 Nobel Prize in Physics.

However, if even a small fraction of the anisotropy can be associated with structure in the Milky Way, the cosmological interpretations of the data could be called into question.

Verschuur, a pioneer in the science of radio astronomy, has been studying the properties of the Milky Way using interstellar HI for almost 50 years. According to his recent work, it appears that many of the small-scale structures observed by WMAP are correlated with HI.

To describe Verschuur's discovery as controversial would be an understatement. "I realize that my results may not be readily accepted by traditional cosmologists," Verschuur says, "but I hope they will at least consider the possibility that their data may have been compromised by what appears to be a previously unidentified source of weak radio emission originating from our own Galaxy."

Verschuur points out that the WMAP researchers went to enormous lengths to remove contributions from known physical processes occurring in the Milky Way, but the WMAP signals associated with the HI may result from a previously unidentified process. "No one could have foreseen the existence of this newly discovered relationship," Verschuur continues. "After all, a comprehensive HI survey for the northern sky was only completed in 1997 and the all-sky version became widely available even more recently, in 2005."

It will be challenging for cosmologists to prove that the weak radio signals detected by WMAP are not originating from the Milky Way. Verschuur points out that a more fruitful approach may be to determine whether or not something new can be learned about the physics of interstellar HI structure by considering examples of the close associations between HI and the anisotropy observed by WMAP.

As a student of interstellar HI, Verschuur is excited by his new discovery. "I now treat the WMAP peaks as markers that indicate where to focus my efforts," he says.

Further study of the relationships between HI and small-scale structure observed by WMAP will surely reveal a host of new information about the physics and dynamics of our own Milky Way Galaxy.

The new discovery, if confirmed, means that the structure superimposed on the cosmic microwave background is produced in the Milky Way and does not have a cosmic origin. Thus the cosmic microwave background signal from the early universe may be smoother than anyone expected, which raises new questions as to how structure ever emerged in the universe to create galaxies.

Verschuur holds out the hope that bright young theorists will tackle this problem and that some members of a new generation of radio astronomers will focus on the Milky Way to study interstellar HI using the WMAP signals to target their research.

The first inkling that a Milky Way component was still present in the WMAP all-sky image came while Verschuur was preparing illustrations for his new book on radio astronomy, The Invisible Universe, published in early 2007. He had available a color print of the all-sky image of the WMAP data and another of the HI data (integrated over all velocities frpm 450 to 400 km/s) to the same scale.

He couldn't hellp noticing intriguing similarities between structures in the two maps. That seemed to merit a closer look. At the time he had been working with the HI data as part of an unrelated project and had available HI maps at dozens of velocities that could quickly compared to details in the WMAP structure. Note that due to motion of the gas in space, the HI emission is observed over a wide range of velocities introduced by the Doppler effect, which shifts the observed frequency of the HI emission by slight amounts.

The WMAP data were subsequently made available to him by Wayne Landsman and Gary Hinshaw of the WMAP team based at the Goddard Space Flight Center.

Verschuur has produced over 1,000 maps of HI structure in small areas of sky for comparison with the WMAP data. "These comparisons reveal hundreds of close associations between HI and WMAP features and it will take years to fully report this work. This field is wide open for others to get involved.

Community
Email This Article
Comment On This Article

Related Links
Stellar Chemistry, The Universe And All Within It



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


Scientists Have Discovered A Connection Between Active Galactic Nuclei And The Most Energetic Known Cosmic Rays
Granada, Spain (SPX) Nov 12, 2007
A group of scientists from 17 countries, formed by researchers of the Universidad de Granada, has proved that the sources of the most energetic particles ever detected do not come from directions uniformly distributed in the firmament, but they aim at areas in which there are galaxies with active nuclei in the centre from a relatively close distance.







  • Russia to stay at Baikonur until 2020
  • Rosetta Closing In On Earth Again For Second Gravity Boost
  • Repair Shops For Broken DNA
  • Spaceship Mockup

  • The Appeal Of Mars
  • Opportunity's Second Martian Birthday At Cape Verde
  • Spirit To Head North For The Winter
  • Opportunity Studies Bathtub Ring In Victoria

  • Zenit Launch Delayed Until November 14
  • United Launch Alliance Successfully Completes First Operational Delta IV Heavy Launch
  • Arianespace's 5th Ariane 5 Mission Is Cleared For November 9 Liftoff
  • Skynet 5B Satellite Ready For Launch On 9th November

  • Earth Observation Essential For Geohazard Mitigation
  • Fujifilm Unveils GPS-Based Data Tape Tracker
  • SPOT - The World's First Satellite Messenger Now Shipping
  • Vacation Photos Create 3D Models Of World Landmarks

  • Data For The Next Generations
  • Goddard Instrument Makes Cover Of Science
  • Checking Out New Horizons
  • Pluto-Bound New Horizons Sees Changes In Jupiter System

  • A Galaxy For Science And Research
  • Cosmological Data Affected By An Unexpected Source Of Radiation In Interstellar Space
  • Scientists Have Discovered A Connection Between Active Galactic Nuclei And The Most Energetic Known Cosmic Rays
  • Stellar Forensics With Striking New Chandra Image

  • Russia And India Sign Joint Lunar Research Deal
  • Japan Set To Bring The Moon To Your Wall TV
  • China To Open Moon Probe Projects For Public Tender
  • Chang'e-1 To Start Lunar Probe In Late November

  • German chancellor says satnav financing plan to be drafted soon
  • Personal Navigation Devices Will Surpass 100 Million Units By 2011
  • V7 Launches New Portable Navigation Devices
  • Magellan Showcases Ultra-Thin Maestro And Magellan Roadmate Auto Navigation Devices

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2007 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement