Abstract: |
The influence of large-scale density fluctuations on structure formation on small scales is described by the three-point correlation function (bispectrum) in the so-called “squeezed configurations.” This bispectrum is generated by non-linear gravitational evolution and possibly also by inflationary physics. We show that the sqeezed-limit bispectrum can be measured without employing three-point function estimators. Specifically, we use the “position-dependent power spectrum,” i.e., the power spectrum measured in smaller subvolumes of the survey (or simulation box), and correlate it with the mean overdensity of the corresponding subvolume. This correlation directly measures an integral of the bispectrum dominated by the squeezed configurations. Measuring this correlation is only slightly more complex than measuring the power spectrum itself, and sidesteps the considerable complexity of the full bispectrum estimation. We apply this technique to the BOSS DR10 CMASS sample. Combining the two- and three-point correlation functions, we break the degeneracies between the linear bias, growth rate, and sigma8, and put constraints on these parameters. |