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.
Angelica de Oliveira-Costa &
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.
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
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.