The impending digital-TV transition has a forgotten victim: the big bang. You can tune an analog set between broadcast channels and see static, part of which is energy left over from the hot primordial universe. This static is known as the cosmic microwave background radiation, and its discovery in the 1960s proved the big bang theory. But on a digital TV, the best you can do is "The Big Bang Theory".

Last week at the American Astronomical Society's meeting, astronomers announced the detection of a second type of radio static from the heavens, and although it may not come from an era quite as ancient as TV snow does, it may probe the period immediately afterward—an equally mysterious time when the first stars and black holes were lighting up. That is, if the signal proves real.

The team, led by Alan Kogut of the NASA Goddard Space Flight Center, took measurements with a radio antenna named ARCADE that dangled from a high-altitude balloon over eastern Texas in July 2006. At radio frequencies greater than 10 gigahertz the radio emission matched that of the microwave background, but at lower frequencies it was several times stronger. Such an excess first emerged in the late 1960s and was mapped in 1981 by Glyn Haslam of the Max Planck Institute for Radio Astronomy in Bonn, Germany, but few astronomers thought much of it until now. "Maybe we should have taken it seriously all this time," says David Spergel, a Princeton University astrophysicist.

The reason for their skepticism was that background measurements are notoriously tricky. A background, by definition, is what's left after you account for everything you already know. Astronomers measure the total radiation coming from the sky and subtract off the radiation generated by the instrument itself, by our own planet and civilization, and by known celestial bodies.

As anyone who has balanced a checkbook knows, the act of subtraction has to be done with the utmost precision or you may erroneously believe you have some leftover light (or cash). Many "discoveries" of background radiation evaporated as data became more precise, and the ones that endured faced a hard slog to prove themselves.

"Measurements of the extragalactic background radiation are always hard to get, because this signal is very faint and, as a result, its detection is strongly dependent on how well one can remove the sources of contamination," says Angelica De Oliveira-Costa, an expert on cosmic background observations at the Massachusetts Institute of Technology.

The surviving signals include not only the microwave background but also three others that peak at different wavelengths: infrared light, visible light, and x-rays.

ARCADE's detection of a cosmic radio background must now run the gauntlet, too. "It's a tough measurement," says Mark Devlin of the University of Pennsylvania, an astronomer who has done similar work. "Unfortunately, most of the things that could go wrong could cause an excess."

He says that although the team used an innovative antenna design and took pains to correct for noise, errors may still have occurred. The device used to calibrate the radio receiver was less precise at low frequencies, where the putative signal appeared; the antenna had very low resolution, some 12 degrees on the sky, which could create a spurious signal at low frequencies; and the instrument took only about two and a half hours of data and covered only a small portion of the sky. "I'd like to see it done one more time, at least," Devlin says.

1 Comments

1. 1. rmforall 02:14 AM 1/20/09

   ubiquitous bright blue 1-12 pixel sources on darker 3D fractal web in five 2007.09.06 IR and visible light HUDF images, Nor Pirzkal, Sangeeta Malhotra, James E Rhoads, Chun Xu, -- might be clusters of earliest hypernovae in recent cosmological simulations: Rich Murray 2008.08.17
   rmforall.blogspot.com/2008_08_01_archive.htm
   Sunday, August 17, 2008
   groups.yahoo.com/group/AstroDeep/25
   groups.yahoo.com/group/rmforall/85
   
   www.flickr.com/photos/rmforall/1349101458/in/photostream/
   
   The 5 closeups are about 2.2x2.2 arc-seconds wide and high, about 70x70 pixels.
   The HUDF is 315x315 arc-seconds, with N at top and E at left.
   Each side has 10,500x10,500 pixels at 0.03 arc-second per pixel.
   
   Click on All Sizes and select Original to view the highest resolution image of 3022x2496 pixels, which can be also be conveniently seen directly at their Zoomable image:
   
   www.spacetelescope.org/images/html/zoomable/heic0714a.html
   
   Notable in the deep background of the five closeups are ubiquitous bright blue sources, presumably extremely hot ultraviolet before redshifting, 1 to a dozen or so pixels, as single or short lines of spots, and a few irregular tiny blobs, probably, as predicted in many recent simulations, the earliest massive, short-lived hypernovae, GRBs with jets at various angles to our line of sight, expanding bubbles, earliest molecular and dust clouds with light echoes and bursts of star formation, and first small dwarf galaxies, always associated with a subtle darker 3D random fractal mesh of filaments of H and He atomic gases.
   
   As a scientific layman, I am grateful for specific cogent, civil feedback, based on the details readily visible in images in the public domain.
   
   www.spacetelescope.org/images/html/heic0714a.html
   
   Hubble and Spitzer Uncover Smallest Galaxy Building Blocks
   
   notable bright blue tiny sources on darker 3D fractal web in HUDF VLT ESO 28 images from 506 galaxies, z about 6 , RJ Bouwens, GD Illingworth,
   JP Blakeslee, M Franx 2008.02.04 draft 36 page: Rich Murray 2008.08.17
   rmforall.blogspot.com/2008_08_01_archive.htm
   Sunday, August 17, 2008
   groups.yahoo.com/group/AstroDeep/26
   groups.yahoo.com/group/rmforall/86
   
   bright blue 1-4 pixel sources on darker 3D fractal web in IR and visible light
   HUDF images -- might be the clusters of earliest hypernovae in the Naoki Yoshida and Lars Hernquist simulation: Rich Murray 2008.07.31
   rmforall.blogspot.com/2008_07_01_archive.htm
   Thursday, July 31, 2008
   groups.yahoo.com/group/AstroDeep/24
   groups.yahoo.com/group/rmforall/84
   
   Rich Murray, MA Room For All rmforall@comcast.net 505-501-229

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