Different Formation Scenarios of Counter-rotating Stellar Disks in Nearby Galaxies

TL;DR

This study analyzes 101 nearby galaxies with counter-rotating stellar disks using IFU data, revealing different formation scenarios influenced by gas abundance and angular momentum factors across galaxy populations.

Contribution

It classifies counter-rotating stellar disks into four types and links their formation scenarios to galaxy properties and evolutionary stages.

Findings

Four types of counter-rotating stellar disks identified

Formation scenarios vary with galaxy population and properties

Key factors include gas abundance and angular momentum efficiency

Abstract

Using the integral field unit (IFU) data from Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we select a sample of 101 galaxies with counter-rotating stellar disks and regularly-rotating ionized gas disk. We classify the 101 galaxies into four types based on the features of their stellar velocity fields. The relative fractions and stellar population age radial gradients of the four types are different in blue cloud (BC), green valley (GV) and red sequence (RS) populations. We suggest different formation scenarios for the counter-rotating stellar disks, and the key factors in the formation of counter-rotating stellar disks include: (1) the abundance of pre-existing gas in progenitor, (2) the efficiency in angular momentum consumption.