Date Published:
November 1, 2017
Abstract:
We investigate the three-point correlation function (3PCF) in thesqueezed limit by considering galaxy pairs as discrete objects andcross-correlating them with the galaxy field. We develop an efficientalgorithm using fast Fourier transforms to compute suchcross-correlations and their associated pair-galaxy bias b
p,g and the squeezed 3PCF coefficient Q
eff. We implementour method using N-body cosmological simulations and a fiducial halooccupation distribution (HOD) and present the results in both the realspace and redshift space. In real space, we observe a peak in b
p,g and Q
eff at pair separation of ∼2 Mpc, attributedto the fact that galaxy pairs at 2 Mpc separation trace the most massivedark matter haloes. We also see strong anisotropy in the b
p,g and Q
eff signals that track the large-scalefilamentary structure. In redshift space, both the 2 Mpc peak and theanisotropy are significantly smeared out along the line of sight due tofinger-of-God effect. In both the real space and redshift space, thesqueezed 3PCF shows a factor of 2 variation, contradicting thehierarchical ansatz, but offering rich information on the galaxy-haloconnection. Thus, we explore the possibility of using the squeezed 3PCFto constrain the HOD. When we compare two simple HOD models that areclosely matched in their projected two-point correlation function(2PCF), we do not yet see a strong variation in the 3PCF that is clearlydisentangled from variations in the projected 2PCF. Nevertheless, wepropose that more complicated HOD models, e.g. those incorporatingassembly bias, can break degeneracies in the 2PCF and show adistinguishable squeezed 3PCF signal.
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