Evolution of Spiral Arm Pitch Angle

We measured the pitch angles of more than 100 spiral galaxies with redshifts less than 1.2 in the GOODS North and South fields. We compared the pitch angles to those of a complete sample of local galaxies. Spiral arm pitch angles seem to have increased (that is, spirals have loosened) since z = 0.5. Selection and measurement biases make more distant statistics untrustworthy.