The Anisotropy in the Galaxy Velocity Field Originated from the Gravitational Pancaking Effect

Abstract

We analyze the Millennium run semi-analytic galaxy catalog to explore quantitatively the gravitational pancaking effect on the orientation of galaxy velocity field. We first calculate the probability density distribution of the cosine of the angle between the velocity of a field galaxy and the direction normal to a local pancake plane which is determined using two nearest neighbor field galaxies. A clear signal of alignment is detected for the case that the pancake scale is in the range of $5-8h^{-1}$ Mpc. The tendency of the velocity-pancake alignment is found to still exist when the pancakes are determined using three neighbor galaxies, indicating that it has a spatial coherence. The degree of the velocity-pancake alignment is shown to increase with the velocity magnitude and the local density, while it decreases with the separation distance from the galaxy to the pancake and disappears when the pancake has a filamentary shape. A final conclusion is that our work may provide another clue to understanding the large-scale structure in the universe.

accepted by ApJL, new analyses included, discussions improved

References in corpus (4)

• Simulating the joint evolution of quasars, galaxies and their large-scale distribution
• Tidal Torques and the Orientation of Nearby Disk Galaxies
• Detection of the effect of cosmological large-scale structure on the orientation of galaxies
• Intrinsic Inclination of Galaxies embedded in Cosmic Sheets and its Cosmological Implications: An Analytic Calculation

Cited by in corpus (8)

• Global and Local Effects of Rotation: Observational Aspects
• The Orientation of Galaxies in Galaxy Clusters
• Remarks on the methods of investigations of alignment of galaxies
• Investigation of the orientation of galaxies in clusters: the importance, methods and results of research
• The distribution of galaxies gravitational field stemming from their tidal interaction
• The non-Gaussian distribution of galaxies gravitational fields
• Orientation of galaxies in structures
• Evolution of the Pancaking Effect in a LCDM Cosmology