Metallicity of the polar disk in NGC4650A: constraints for cold accretion scenario

TL;DR

This study measures the metallicity of the polar disk in NGC4650A to test if cold gas accretion from cosmic filaments explains its formation, finding similarities with late-type galaxies supporting this scenario.

Contribution

It provides observational constraints on the cold accretion formation scenario of polar disks by analyzing metallicities in NGC4650A.

Findings

Metallicity of the polar disk is similar to late-type galaxies.

Results support formation via cold gas accretion from cosmic web filaments.

Study uses high-resolution optical and near-infrared spectra.

Abstract

We used high resolution spectra in the optical and near-infrared wavelength range to study the abundance ratios and metallicities of the HII regions associated with the polar disk in NGC4650A, in order to put constraints on the formation of the polar disk through cold gas accretion along a filament; this might be the most realistic way by which galaxies get their gas. We have compared the measured metallicities for the polar structure in NGC4650A with those of different morphological types and we have found that they are similar to those of late-type galaxies: such results is consistent with a polar disk formed by accretion from cosmic web filaments of external cold gas.