Day 1247

Tuesday.

1704.06273
Intrinsic Alignment in redMaPPer clusters -- II. Radial alignment of satellites toward cluster centers
Huang, Mandelbaum, Freemen, Chen, Rozo, Rykoff

Study the orientations of satellite galaxies in redMapper clusters constructed from SDSS at 0.1<z<0.35 to determine whether there is any preferential tendency for satellites to point radially toward cluster centers.  Analyze the satellite alignment (SA) signal based on 3 shape measurement methods (re-Gaussianization, deVaucouleurs, and isophotal shapes), which trace galaxy light profiles at different radii.  While no set SA signal is detected using re-Gaussianization shapes across the entire sample, the observed SA signal reaches a statistically significant level when using a subsample of satellites with higher luminosity.  Detect the strongest SA signals using isophotal shapes, followed by the deVaucouleurs shapes, and investigate the impact of noise, systematics, and real physical effects such as isophotal twisting in the comparison between the results based on different shape measurement methods.  After studying the correlation of the SA signal with a total of 17 galaxy and cluster properties, find that the measured SA signal is strongest for satellites with the following characteristics: higher luminosity, smaller distance to the cluster center, rounder in shape, higher bulge fraction in the light profile, distributed preferentially along the major axis directions of their centrals, and residing in clusters with less luminous centrals.  Finally, provide physical explanations for the identified dependencies, and discuss the connection to theories of SA.