On The Stellar And Baryonic Mass Fractions Of Central Blue And Red Galaxies

Using the abundance matching technique, we infer the local stellar and bary- onic mass-halo mass (Ms-Mh and Mb-Mh) relations separately for central blue and red galaxies (BGs and RGs). The observational inputs are the SDSS central BG and RG stellar mass functions and the measured gas mass-Ms relations. For halos associated to central BGs, the distinctCDM halo mass function is used and set up to exclude: (i) the observed group/cluster mass function and (ii) halos with a central major merger at resdshifts z ≤ 0.8. For central RGs, the complement of this mass function to the total one is used. At Mh > 10 11.5 M⊙, the Ms of RGs tend to be higher than those of BGs for a given Mh, the difference not being larger than 1.7. At Mh < 10 11.5 M⊙, this trend is inverted. For BGs (RGs): (a) the maximum value of fs = Ms/Mh is 0.021 +0.016 −0.009 (0.034 +0.026 −0.015) and it is attained at log(Mh/M⊙) = 12.0 (= 11.9); (b) fs ∝ Mh (fs ∝ Mh 3 ) at the low-mass end while at the high-mass end, fs ∝ Mh −0.4 (fs ∝ Mh −0.6 ). The baryon mass fractions, fb=Mb/Mh, of BGs and RGs reach maximum values of fb = 0.028 +0.018 −0.011 and fb = 0.034 +0.025 −0.014 , respectively. At Mh < 10 11.3 M⊙, the dependence of fb on Mh is much steeper for RGs than for BGs. We discuss the differences found in the fs-Mh and fb-Mh relations between BGs and RGs in the light of semi-empirical galaxy evolution inferences.