Our Hubble volume:


A 3-year WMAP version of the foreground cleaned map is downloadable near the bottom of this page.

If you got here from the New York Times soccer ball story or the story about the Nature paper suggesting that the Universe is a dodecahedron, you'll find our paper placing limits on small universes here. For a WMAP3 update, see this paper by Key et al which rules out the dodecahedron model at high significance. (Soccer enthusiasts will note that a soccer ball is made up of pentagons and hexagons and isn't a dodecahedron.)


This is our best guess as to what the cosmic microwave background looks like, from the paper described below. Our entire observable universe is inside this sphere of radius 13.3 billion light-years, with us at the center. Space continues outside the sphere, but this opaque glowing wall of hydrogen plasma hides it from our view. This censorship is frustrating, since if we could see merely 380000 light-years beyond it, we would behold the beginning of the universe. Light from still further away would not yet have had time to reach us, but most inflation theories predict that space is infinite. (Note for pundits: These "distances" are merely light travel times. After emitting the CMB 13.3 billion years ago, the sphere above has kept expanding and is currently about 40 billion light-years away; its comoving radius is, was and always will be 40 billion light years.)

Title: A high resolution foreground cleaned CMB map from WMAP

Please click here to download a ps-file the paper with full-resolution figures. Click here for pdf. Because of the astro-ph size restrictions, the low-resolution versions there unfortunately don't do justice to the WMAP data or our method.

Authors:

Max Tegmark, Angelica de Oliveira-Costa & Andrew Hamilton

Abstract:

We perform an independent foreground analysis of the WMAP maps to produce a cleaned CMB map (available below), useful for cross-correlation with, e.g., galaxy and X-ray maps. We use a variant of the Tegmark & Efstathiou (1996) technique that is completely blind, making no assumptions about the CMB power spectrum, the foregrounds, WMAP detector noise or external templates. Compared with the foreground-cleaned internal linear combination map produced by the WMAP team, our map has the advantage of containing less non-CMB power (from foregrounds and detector noise) outside the Galactic plane. The difference is most important on the the angular scale of the first acoustic peak and below, since our cleaned map is at the highest (13') rather than lowest (49') WMAP resolution. We also produce a Wiener filtered CMB map, representing our best guess as to what the CMB sky actually looks like, as well as CMB-free maps at the five WMAP frequencies useful for foreground studies.
We argue that our CMB map is clean enough that the lowest multipoles can be measured without any galaxy cut, and obtain a quadrupole value that is slightly less low than that from the cut-sky WMAP team analysis. This can be understood from a map of the CMB quadrupole, which shows much of its power falling within the Galaxy cut region, seemingly coincidentally. Intriguingly, both the quadrupole and the octopole are seen to have power suppressed along a particular spatial axis, which lines up between the two, roughly towards (l,b) ~ (-80,60) in Virgo.

Reference info:

astro-ph/0302496, Phys. Rev. D, 68, 123523

Stuff to download

 All of these maps are 13MB files in HEALPix format with resolution nside=512 RING ordering of the 12*512**2=3145728 pixels, in thermodynamic millikelvins just as in the WMAP distribution. They have monopole and dipole set to zero. Please feel free to use them for whatever you want. Please email me if you'd like other material from these papers or if you have questions. If you'd like to use the three-year maps, you'd also want to cite astro-ph/0603369.
The same map as above, but in Mollweide projection. Both figures have the same color scale and both are in Galactic coordinates, but the (stationary) sphere above shows merely the northern half.
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This page was last modified May 11, 2006.
tegmark@mit.edu