Formation of N-rich field stars in the high-density building blocks of the Galactic bulge

Recent observational studies of the Galactic bulge by APOGEE have revealed that about 1 per cent of the bulge stars have rather high nitrogen abundances ([N/Fe] > 0.5). We here numerically investigate in what physical conditions these N-rich stars (NRSs) can be formed in spherical and discy stellar systems with stellar masses of 10(7)-10(9)M(circle dot) that are the bulge's building blocks. The principal results are as follows. A large fraction (>0.5) of new stars formed from interstellar medium polluted (ISM) by ejecta of asymptotic giant branch stars can have [N/Fe]> 0.5within stellar systems, if the gas mass fraction of ISM(f(g)) is low(