Stellar Population Synthesis with Distinct Kinematics: Multi-Age Asymmetric Drift in SDSS-IV MaNGA Galaxies

TL;DR

This paper introduces two algorithms to measure asymmetric drift in unresolved stellar populations across different ages in galaxy disks, using MaNGA data, revealing diverse age-dependent kinematic profiles.

Contribution

Develops and tests two novel algorithms for extracting age-dependent asymmetric drift from integral-field spectroscopic data of galaxies.

Findings

Different AD profiles for young and old stars in galaxy disks.

Algorithms validated with mock spectra and real MaNGA data.

Demonstrates the method on seven galaxies similar to the Milky Way.

Abstract

We present the first asymmetric drift (AD) measurements for unresolved stellar populations of different characteristic ages above and below 1.5 Gyr. These measurements sample the age-velocity relation (AVR) in galaxy disks. In this first paper we develop two efficient algorithms to extract AD on a spaxel-by-spaxel basis from optical integral-field spectroscopic (IFS) data-cubes. The algorithms apply different spectral templates, one using simple stellar populations and the other a stellar library; their comparison allows us to assess systematic errors in derived multi-component velocities, such as template-mismatch. We test algorithm reliability using mock spectra and Monte Carlo Markov Chains on real data from the MaNGA survey in SDSS-IV. We quantify random and systematic errors in AD as a function of signal-to-noise and stellar population properties with the aim of applying this technique to large subsets of the MaNGA galaxy sample. As a demonstration of our methods, we apply them to an initial sample of seven galaxies with comparable stellar mass and color to the Milky Way. We find a wide range of distinct AD radial profiles for young and old stellar populations.