baryon acoustic volatility

Eyal Kazin (NYU) spoke today in a long group meeting session about the Baryon Acoustic Feature in data and simulations (or mocks, really, which are simulations of particular data sets). He showed that we actually got lucky that we detected the BAF in SDSS-I. There was a better-than-ten-percent chance that we would have seen no feature at all. And yet when we did detect it, we could measure its location (length scale) to a few percent! This is because the correlation function is very stable in shape, but unstable in amplitude; or because the data points in a plot of the correlation function amplitude as a function of scale are incredibly strongly correlated. Prospects for SDSS-III are good, but there is a lot of cosmic variance to disappoint us.

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