The angular momentum of disc galaxies at z=1
  We investigate the relation between stellar mass and specific stellar angular
momentum, or `Fall relation', for a sample of 17 isolated, regularly rotating
disc galaxies at z=1. All galaxies have a) rotation curves determined from
Halpha emission-line data; b) HST imaging in optical and infrared filters; c)
robust determinations of their stellar masses. We use HST images in f814w and
f160w filters, roughly corresponding to rest-frames B and I bands, to extract
surface brightness profiles for our systems. We robustly bracket the specific
angular momentum by assuming that rotation curves beyond the outermost Halpha
rotation point stay either flat or follow a Keplerian fall-off. By comparing
our measurements with those determined for disc galaxies in the local Universe,
we find no evolution in the Fall relation in the redshift range 0<z<1,
regardless of the band used and despite the uncertainties in the stellar
rotation curves at large radii. This result holds unless stellar masses at z=1
are systematically underestimated by more than 50%. Our findings are compatible
with expectations based on a LCDM cosmological framework and support a scenario
where both the stellar Tully-Fisher and mass-size relations for spirals do not
evolve significantly in this redshift range.
