REGARDING THE LINE-OF-SIGHT BARYONIC ACOUSTIC FEATURE IN THE SLOAN DIGITAL SKY SURVEY AND BARYON OSCILLATION SPECTROSCOPIC SURVEY LUMINOUS RED GALAXY SAMPLES

We analyze the line-of-sight baryonic acoustic feature in the two-point correlation function xi of the Sloan Digital Sky Survey luminous red galaxy (LRG) sample (0.16 < z < 0.47). By defining a narrow line-of-sight region, r(p) < 5.5 h(-1) Mpc, where r(p) is the transverse separation component, we measure a strong excess of clustering at similar to 110 h(-1) Mpc, as previously reported in the literature. We also test these results in an alternative coordinate system, by defining the line of sight as 0 < 3 degrees, where 0 is the opening angle. This clustering excess appears much stronger than the feature in the better- measured monopole. Lambda fiducial Lambda CDM nonlinear model in redshift space predicts a much weaker signature. We use realistic mock catalogs to model the expected signal and noise. We find that the line- of- sight measurements can be explained well by our mocks as well as by a featureless xi = 0. We conclude that there is no convincing evidence that the strong clustering measurement is the line-of-sight baryonic acoustic feature. We also evaluate how detectable such a signal would be in the upcoming Baryon Oscillation Spectroscopic Survey (BOSS) LRG volume. Mock LRG catalogs (z < 0.6) suggest that (1) the narrow line- of- sight cylinder and cone defined above probablywill not reveal a detectable acoustic feature in BOSS; (2) a clustering measurement as high as that in the current sample can be ruled out (or confirmed) at a high confidence level using a BOSS- sized data set; (3) an analysis with wider angular cuts, which provide better signal- to- noise ratios, can nevertheless be used to compare line-of-sight and transverse distances, and thereby constrain the expansion rate H(z) and diameter distance D-A(z).