Pitch angles of distant spiral galaxies

TL;DR

This study analyzes the pitch angles of distant spiral galaxies at z~0.7 to estimate their rotation velocities and investigate luminosity evolution, using a calibrated relation from nearby galaxies.

Contribution

It introduces a method to estimate rotation velocities of distant galaxies from pitch angles, supporting studies of galaxy evolution.

Findings

Estimated rotation velocities with ~50 km/s accuracy.

Tully-Fisher relation for distant galaxies aligns with local observations.

Evidence for luminosity evolution in spiral galaxies.

Abstract

We have studied the pitch angles of spiral arms for 31 distant galaxies at z~0.7 from three Hubble Deep Fields (HDF-N, HDF-S, HUDF). Using the pitch angle - rotation velocity relation calibrated from nearby galaxies, we have estimated the rotation velocities of galaxies from the deep fields. These estimates have a low accuracy (~50 km/s), but they allow low-mass and giant galaxies to be distinguished. The Tully-Fisher relation constructed using our velocity estimates shows satisfactory agreement with the actually observed relations for distant galaxies and provides evidence for the luminosity evolution of spiral galaxies.