A novel approach for calculating galaxy rotation curves using spaxel cross-correlation and iterative smoothing

TL;DR

This paper introduces a new method for measuring galaxy rotation curves by cross-correlating spectral pixels and iteratively smoothing, which is effective even with very low signal-to-noise data.

Contribution

The paper presents a novel spectral pixel cross-correlation technique combined with iterative smoothing for accurate LOS velocity measurements in galaxies, especially at low S/N levels.

Findings

Accurately recovers input velocities on simulated data across different spectral types.

Maintains reliable velocity measurements at very low S/N (~1).

Demonstrates promising results on real galaxy data.

Abstract

Precise measurements of the internal dynamics of galaxies have proven of great importance for understanding the internal dark matter distribution of galaxies. We present a novel method for measuring the line-of-sight (LOS) velocities across the face of galaxies by cross-correlation of spectral pixels (spaxels) and an iterative method of smoothing. On simulated data the method can accurately recover the input LOS velocities for different types of spectra (absorption line dominated, emission line dominated, and differing shapes of the continuum), and can handle stellar population radial gradients. Most important of all, it continues to provide reliable measurements of LOS velocities with reasonable uncertainties even when the spectra are very low signal-to-noise (approaching $\sim 1$), which is a challenge for traditional template-fitting approaches. We apply our method to data from a real MaNGA galaxy as a demonstration and find promising results with good precision. This novel approach can be complementary to existing methods primarily based on template fitting.