The Large-scale Structure Supplies the Formation of Gas-star Misaligned Galaxies

Abstract

Using the integral field unit data from the Mapping Nearby Galaxies at Apache Point Observatory survey, we build a sample of gas-star misaligned galaxies. The large-scale environment of misaligned galaxies is dominated by filaments and clusters, while it is less dense relative to the gas-star aligned control galaxies. The direction of the large-scale structure (LSS) is defined by its minor axis ( ${{\boldsymbol{e}}}_{{\bf{3}}}$ ), which indicates the slowest collapsing direction. For the aligned controls, the gas and stellar spins are preferentially perpendicular to ${{\boldsymbol{e}}}_{{\bf{3}}}$ , since these galaxies reside in high-mass host halos. For the misaligned galaxies, the gas spins also tend to be perpendicular to ${{\boldsymbol{e}}}_{{\bf{3}}}$ , suggesting that misaligned gas is recently accreted from the LSS. Meanwhile, there is no correlation between their stellar spins and ${{\boldsymbol{e}}}_{{\bf{3}}}$ . There are two possible explanations for this observational phenomenon: (1) the large-scale environments of misaligned galaxies evolve as they grow, with stellar angular momenta acquired in different environments having different orientations; (2) the correlation between stellar spins and the LSS is smeared out since a relatively higher portion of misaligned galaxies in sheet environments are statistically analyzed together with those in filament environments.

Keywords

• Galaxy kinematics
• Galaxy evolution