Detection of the Intrinsic Spin Alignments in Isolated Spiral Pairs

Abstract

An observational evidence for the intrinsic galaxy alignments in isolated spiral pairs is presented. From the catalog of the galaxy groups identified by Tempel et al. in the flux limited galaxy sample of the Sloan Digital Sky Survey Data Release 10, we select those groups consisting only of two spiral galaxies as isolated spiral pairs and investigate if and how strongly the spin axes of their two spiral members are aligned with each other. We detect a clear signal of intrinsic spin alignment in the isolated spiral pairs, which leads to the rejection of the null hypothesis at the $99.9999\%$ confidence level via the Rayleigh test. It is also found that those isolated pairs comprising two early-type spiral galaxies exhibit the strongest signal of intrinsic spin alignment and that the strength of the alignment signal depends on the angular separation distance as well as on the luminosity ratio of the member galaxies. Using the dark matter halos consisting of only two subhalos resolved in the EAGLE hydrodynamic simulations, we repeat the same analysis but fail to find any alignment tendency between the spin angular momentum vectors of the stellar components of the subhalos, which is in tension with the observational result. A couple of possible sources of this apparent inconsistency between the observational and the numerical results are discussed.

Accepted for publication in ApJ, revised version, Rayleigh tests included, von Mises distributions used for fitting, 11 figures, 3 tables

References in corpus (11)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• The EAGLE simulations of galaxy formation: public release of halo and galaxy catalogues
• Testing $\Lambda$CDM at the lowest redshifts with SN Ia and galaxy velocities
• Marginal evidence for cosmic acceleration from Type Ia supernovae
• The Large-Scale Orientations of Disk Galaxies
• Angular momentum properties of haloes and their baryon content in the Illustris simulation
• Impact of Baryonic Physics on Intrinsic Alignments
• Dynamics of the Local Group: the Dwarf Galaxies
• Cosmic Voids in Evolving Dark Sector Cosmologies: the Low Redshift Universe
• The dynamics of the local group as a probe of Dark Energy and Modified Gravity

Cited by in corpus (3)

• Living with Neighbors. III. The Origin of the Spin$-$Orbit Alignment of Galaxy Pairs: A Neighbor versus the Large-scale Structure
• Living with Neighbors. IV. Dissecting the Spin$-$Orbit Alignment of Dark Matter Halos: Interacting Neighbors and the Local Large-scale Structure
• Living with Neighbors. V. Better-aligned Spiral+Spiral Galaxy Pairs Show Stronger Star Formation