[astro-ph/0411633] The CMB temperature power spectrum from an improved analysis of the Archeops data

Authors:  M. Tristram, G. Patanchon, J. F.Macias-Perez, P. Ade, A. Amblard, R. Ansari, E. Aubourg, A. Benoit, J.-Ph. Bernard, A. Blanchard, J. J. Bock, F. R. Bouchet, A. Bourrachot, P. Camus, J.-F. Cardoso, F. Couchot, P. de Bernardis, J. Delabroui
Abstract:  We present improved results on the measurement of the angular power spectrum of the Cosmic Microwave Background (CMB) temperature anisotropies using the data from the last Archeops flight. This refined analysis is obtained by using the 6 most sensitive photometric pixels in the CMB bands centered at 143 and 217 GHz and 20% of the sky, mostly clear of foregrounds. Using two different cross-correlation methods, we obtain very similar results for the angular power spectrum. Consistency checks are performed to test the robustness of these results paying particular attention to the foreground contamination level which remains well below the statistical uncertainties. The multipole range from l=10 to l=700 is covered with 25 bins, confirming strong evidence for a plateau at large angular scales (the Sachs-Wolfe plateau) followed by two acoustic peaks centered around l=220 and l=550 respectively. These data provide an independent confirmation, obtained at different frequencies, of the WMAP first year results.
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Pier Stefano Corasaniti
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[astro-ph/0411633] The CMB temperature power spectrum from a

Post by Pier Stefano Corasaniti » November 24 2004

The ARCHEOPS team has released the latest analysis of the CMB power spectrum, which is in full agreement with WMAP data and therefore provide an indipendent confirmation of WMAP TT spectrum.

What really strikes me is that some of the "weird" data points measured by WMAP seems to appear also in ARCHEOPS.

The binning is different and also the errors are larger, nonetheless my eye see a many sigma deviation for the point at l=40 and also the first peak has a suppressed point in its middle
(see figure 16 of the paper). These features remind me those present in WMAP!!!

Most likely my eyes have seen a mirage, but if not it......what are these points? How can a foreground produce them? Certainly is not a systematic of the experiments, since one is a ballon and the other a satellite, so they are truly different!

Does anyone have a clue? I would be really grateful to hear some comment from ARCHEOPS members.

All the best

Pier-Stefano COrasaniti

Anze Slosar
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Affiliation: Brookhaven National Laboratory
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[astro-ph/0411633] The CMB temperature power spectrum from a

Post by Anze Slosar » November 25 2004

Well, these Archeops plots had had these features for some time now; i have definitelly seen them on a at leat two conferences: what I didn't appreciate till yesterday that ARCHEOPS results are based on much higher frequencies, namelly 147 and 217 Ghz, which is more than factor two higher than W frequency, and at these frequencies the amplitude of the effect still looks the same. So, whatever it is, it looks like it has the same frequency dependence as CMB, indicating it might be real...

There was some discussion about statistical significance of this, for example, Wandelt discusses this: every single multipole is consistent with PS within cosmic variance, only when one integrates over some range of ell values this effects appear... But how big this range is of course a-posteriori, so it is really a difficult thing to asses statistically without being biased either way...

anze

Alessandro Melchiorri
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[astro-ph/0411633] The CMB temperature power spectrum from a

Post by Alessandro Melchiorri » November 26 2004

Uhm, the 'dip' at l=200 in the Archeops data is around 400 uK^2 while for WMAP is 100 uk^2 (just quickly looking at the mean values). Simply put, I don't think Archeops could see the WMAP dip with its error bars ! So, if this thing is real, there is some frequency dependence. Regarding WMAP, I think that Fig.7 in the Hinshaw et al is quite interesting.

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