CosmoCoffee

I just noticed this reanalysis of the WMAP data. I don't know a lot about the pipelines for CMB data. Does anyone have thoughts about this?

Thanks

Adam

Yes, this is interesting, but I couldn't figure out exactly what is different between their analysis of the TOD and WMAP's.

The only thing that was clearly mentioned was that they didn't use data from when the beam is within 7 degrees from outer planets, while WMAP allegedly excluded only within 1.5 degrees. Is that the only difference?!

Dragan Huterer wrote:Yes, this is interesting, but I couldn't figure out exactly what is different between their analysis of the TOD and WMAP's

With hindsight, that may turn out to be the most important result
from Liu & Li 0907.2731: they tried to
analyse the TOD in the same, presumably correct, way that the WMAP
team did, this successfully passed most tests and gave nearly identical
results - except that the quadrupole weakened by half an order of
magnitude. They didn't know why, and suggested that it would be cool
if the WMAP team could help find the difference.

The WMAP team presumably failed to "spot the difference" during the following
seven months, but Liu & Li found it. They also found an elegant way of producing
the supposedly cosmological quadrupole using spacecraft attitude history and no CMB temperature
maps, since the former is where they unintentionally had done something
differently to the WMAP team.

Anyway, that thread is at: http://cosmocoffee.info/viewtopic.php?t=1537

The quadrupole that Lui and Li report for the reprocessed WMAP5 maps, [37.3, 24.4(safe-mode)] [tex]\mu K^2[/tex] is small compared to official released WMAP figure of 108.7 [tex]\mu K^2[/tex]

But it's not that small compared to the distribution of quadrupoles in a /\CDM universe. The WMAP team in their recent paper on anomalies (1001.4758) found a [tex]2\sigma[/tex] range of [40,3200] [tex]\mu K^2[/tex]

Not that this is relevant to the authors idea that the quadrupole isn't cosmological but is an instrument artifact, as argued in 1003.1073.