Top panel: the mean of the log of  the Maximum Tem-perature that \star forming bulge gas" (BGs, see text)  reaches subsequent to the time that it was identi ed, plotted against  the age of the stars which form from that BGs. Middle panel: the mean of  the maximum distance that star forming bulge gas (BGs) reaches from the  centre of the galaxy, plotted against the age of BGs stars. Bottom  panel: the mean angular momentum of BGs stars is plotted against their  age. Red star symbols show the me-dian values at each age. Supernova  feedback heats gas and ejects it from the central region with the  hottest gas travelling the fur- thest from the centre. The ejected gas  absorbs angular momentum from the hot corona and later accreting gas,  returning to the disk with a signi cantly di erent angular momentum  distribution.

with  a signi cantly di erent angular momentum distribution.Within a fully  cosmological hydrodynamical simulation, we form a galaxy which rotates  at 140 km/s, and is characterised by two loose spiral arms and a bar,  indicative of a Hubble Type SBc/d galaxy. We show that our simulated  galaxy has no classical bulge, with a pure disc profile at z=1, well  after the major merging activity has ended. A long-lived bar  subsequently forms, resulting in the formation of a secularly-formed  "pseudo" bulge, with the final bulge-to-total light ratio B/T=0.21. We  show that the majority of gas which loses angular momentum and falls to  the central region of the galaxy during the merging epoch is blown back  into the hot halo, with much of it returning later to form stars in the  disc. We propose that this mechanism of redistribution of angular  momentum via a galactic fountain, when coupled with the results from our  previous study which showed why gas outflows are biased to have low  angular momentum, can solve the angular momentum/bulgeless disc problem  of the cold dark matter paradigm.

See the webside for more details.http://arxiv.org/PS_cache/arxiv/pdf/1105/1105.2562v1.pdf (SY)