Kinematics and Stellar Disk Modeling of Lenticular Galaxies

TL;DR

This study combines spectroscopic observations and N-body modeling to analyze the kinematics and mass distribution of three lenticular galaxies, revealing disk overheating likely caused by external influences.

Contribution

It introduces detailed N-body models of lenticular galaxies incorporating bulge, disk, and dark halo components, and compares these with spectroscopic data to study disk heating.

Findings

Disks of NGC 5440 and outer NGC 338 are dynamically overheated.

Disk heating is common in early-type disk galaxies and likely due to external effects.

Provides estimates of disk mass and dark halo mass for seven galaxies.

Abstract

We present the results of spectroscopic observations of three S0-Sa galaxies: NGC338, NGC 3245, and NGC 5440 at the SAO RAS 6-m BTA telescope. The radial distributions of the line-of-sight velocities and radial velocity dispersions of stars and ionized gas were obtained, and rotation curves of galaxies were computed. We construct the numerical dynamic N-body galaxy models with N > 10^6 point masses. The models include three components: a "live" bulge, a collisionless disk, dynamically evolving to the marginally stable state, and a pseudo-isothermal dark halo. The estimates of radial velocities and velocity dispersions of stars obtained from observations are compared with model estimates, projected onto the line of sight. We show that the disks of NGC 5440 and the outer regions of NGC 338 are dynamically overheated. Taking into account the previously obtained observations, we conclude that the dynamic heating of the disk is present in a large number of early-type disk galaxies, and it seems to ensue from the external effects. The estimates of the disk mass and relative mass of the dark halo are given for seven galaxies, observed at the BTA.