Searching for massive galaxies at z $geq$ 3.5 in GOODS-North

摘要

Aims. We constrain the space density and properties of massive galaxy candidates at redshifts of in the Great Observatories Origin Deep Survey North (GOODS-N) field. By selecting sources in the Spitzer+ IRAC bands, a sample highly complete in stellar-mass is assembled, including massive galaxies that are very faint in the opticalear-IR bands and would be missed by samples selected at shorter wavelengths. Methods. The sample was selected to mag at m using photometric redshifts obtained by fitting the galaxies spectral energy distribution at optical, near-IR bands, and IRAC bands. We also require that the brightest band (in ABscale) in which candidates are detected is the IRAC m band to ensure that the near-IR m (rest-frame) peak is falling in or beyond this band. Results. We found 53 candidates, of masses in the range .At least 81% of these galaxies are missed by traditional LymanBreak selection methods based on ultraviolet light. Spitzer+ MIPSemission is detected for 60% of the sample of galaxy candidates. Although in some cases this might suggest a residual contamination from lower redshift star-forming galaxies or Active Galactic Nuclei, 37% of these objects are also detected in the sub-mm/mm bands in SCUBA, AzTEC, and MAMBOsurveys, and have properties fully consistent with vigorous starburst galaxies at .The comoving number density of galaxies with stellar masses of above 5(a reasonable stellar-mass completeness limit for our sample) is 2.610-5Mpc-3 (using the volume within 3.5