THE DETECTION OF THE LARGE-SCALE ALIGNMENT OF MASSIVE GALAXIES AT z {approx} 0.6
- Partner Group of the Max Planck Institute for Astrophysics at the Shanghai Astronomical Observatory and Key Laboratory for Research in Galaxies and Cosmology of Chinese Academy of Sciences, Nandan Road 80, Shanghai 200030 (China)
- Center for Astronomy and Astrophysics, Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)
- School of Physics, University of the Witwatersrand, P.O. Box Wits, Johannesburg 2050 (South Africa)
We report on the detection of the alignment between galaxies and large-scale structure at z {approx} 0.6 based on the CMASS galaxy sample from the Baryon Oscillation Spectroscopy Survey Data Release 9. We use two statistics to quantify the alignment signal: (1) the alignment two-point correlation function that probes the dependence of galaxy clustering at a given separation in redshift space on the projected angle ({theta}{sub p}) between the orientation of galaxies and the line connecting to other galaxies, and (2) the cos (2{theta})-statistic that estimates the average of cos (2{theta}{sub p}) for all correlated pairs at a given separation s. We find a significant alignment signal out to about 70 h {sup -1} Mpc in both statistics. Applications of the same statistics to dark matter halos of mass above 10{sup 12} h {sup -1} M{sub Sun} in a large cosmological simulation show scale-dependent alignment signals similar to the observation, but with higher amplitudes at all scales probed. We show that this discrepancy may be partially explained by a misalignment angle between central galaxies and their host halos, though detailed modeling is needed in order to better understand the link between the orientations of galaxies and host halos. In addition, we find systematic trends of the alignment statistics with the stellar mass of the CMASS galaxies, in the sense that more massive galaxies are more strongly aligned with the large-scale structure.
- OSTI ID:
- 22118789
- Journal Information:
- Astrophysical Journal Letters, Vol. 770, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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