Pitch angles of distant spiral galaxies
  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.
