The nature of high-redshift galaxies

摘要: Using semi-analytic models of galaxy formation set within the cold dark matter (CDM) merging hierarchy, we investigate several scenarios for nature high-redshift ) Lyman-break galaxies (LBGs). We consider a ‘collisional starburst’ model in which bursts star are triggered by galaxy–galaxy mergers, and find that significant fraction LBGs predicted to be starbursts. This reproduces observed comoving number density bright as function redshift luminosity at with reasonable amount dust extinction. Model have rates, half-light radii, colours internal velocity dispersions good agreement data. Global quantities such rate gas metal content Universe also agree well. Two ‘quiescent’ without starbursts investigated. In one, efficiency remains constant redshift, while other, it scales inversely disc dynamical time, thus increases rapidly redshift. The first quiescent is strongly ruled out, does not produce enough once realistic extinction accounted for. second fits marginally, but underproduces very high A general conclusion must more efficient than locally. collisional starburst appears accomplish this naturally violating other observational constraints.