[astro-ph/0606538] Point source power in three-year Wilkinso
Posted: July 06 2006
This is a quite interesting paper - I hoped that someone else will come up with discussion about it. They refit the residual point source spectrum in WMAP3 and show that n_s moves by about 0.7 sigma: in general I wouldn't care about sub 1-sigma shifts, but this time it moves n_s=1 from the tail of the distribution into a completely ok zone.
Few comments though:
Few comments though:
- I don't like 100-200 bin: it makes \chi^2 horrible and it cannot possibly be a noise fluctuation, unless errors are badly underestimated. I think it is also quite difficult to come up with something that changes things on such large scales.
- \beta=-2 - is assuming this a good assumption? What happens if you put some sensible prior around \beta (say 2\pm0.5)? I would expect that faint sources are not the same population as sources so bright, that you can actually cut them out....
- Poisson distribution: surely, there are some LSS effects in the unresolved sources; what authors do (I think) is to assume white noise for unresolved sources: instead you could do something like Limber between z=0 and 5, fit the amplitude on large scales and extrapolate to smaller scales - surely this would have been better than C_\ell = const?
- Just as an asside - could you detected them via non-Guassianity? If there are not too many sources, you should seem them in bispectrum, I guess?