Quantifying the bimodal color-magnitude distribution of galaxies Export

@article{citeulike:3471278, abstract = {We analyse the bivariate distribution, in color versus absolute magnitude (u-r vs. M\_r), of a low redshift sample of galaxies from the Sloan Digital Sky Survey (SDSS; 2400 deg^2, 0.004\<z\<0.08, -23.5\<M\_r\<-15.5). We trace the bimodality of the distribution from luminous to faint galaxies by fitting double-Gaussians to the color functions separated in absolute magnitude bins. Color-magnitude (CM) relations are obtained for red and blue distributions (early- and late-type, predominantly field, galaxies) without using any cut in morphology. Instead, the analysis is based on the assumption of normal Gaussian distributions in color. We find that the CM relations are well fit by a straight line plus a tanh function. Both relations can be described by a shallow CM trend (slopes of about -0.04, -0.05) plus a steeper transition in the average galaxy properties over about two magnitudes. The midpoints of the transitions (M\_r=-19.8 and -20.8 for the red and blue distributions, respectively) occur around 2x10^10 M\_solar after converting luminosities to stellar mass. Separate luminosity functions are obtained for the two distributions. The red distribution has a more luminous characteristic magnitude and a shallower faint-end slope (M^*=-21.5, alpha=-0.8) compared to the blue distribution (alpha=-1.3 depending on the parameterization). These are approximately converted to galaxy stellar mass functions. The red distribution galaxies have a higher number density per magnitude for masses greater than about 3x10^10 M\_solar. Using a simple merger model, we show that the differences between the two functions are consistent with the red distribution being formed from major galaxy mergers.}, archivePrefix = {arXiv}, author = {Baldry, I. K. and Glazebrook, K. and Brinkmann, J. and Ivezic, Z. and Lupton, R. H. and Nichol, R. C. and Szalay, A. S.}, citeulike-article-id = {3471278}, citeulike-linkout-0 = {http://arxiv.org/abs/astro-ph/0309710}, citeulike-linkout-1 = {http://arxiv.org/pdf/astro-ph/0309710}, day = {25}, eprint = {astro-ph/0309710}, keywords = {cmr, goodintroduction, sloan}, month = {Sep}, posted-at = {2008-10-31 23:54:26}, priority = {3}, title = {Quantifying the bimodal color-magnitude distribution of galaxies}, url = {http://arxiv.org/abs/astro-ph/0309710}, year = {2003} }

TY - JOUR ID - citeulike:3471278 L3 - citeulike-article-id:3471278 N2 - We analyse the bivariate distribution, in color versus absolute magnitude (u-r vs. M_r), of a low redshift sample of galaxies from the Sloan Digital Sky Survey (SDSS; 2400 deg^2, 0.004<z<0.08, -23.5<M_r<-15.5). We trace the bimodality of the distribution from luminous to faint galaxies by fitting double-Gaussians to the color functions separated in absolute magnitude bins. Color-magnitude (CM) relations are obtained for red and blue distributions (early- and late-type, predominantly field, galaxies) without using any cut in morphology. Instead, the analysis is based on the assumption of normal Gaussian distributions in color. We find that the CM relations are well fit by a straight line plus a tanh function. Both relations can be described by a shallow CM trend (slopes of about -0.04, -0.05) plus a steeper transition in the average galaxy properties over about two magnitudes. The midpoints of the transitions (M_r=-19.8 and -20.8 for the red and blue distributions, respectively) occur around 2x10^10 M_solar after converting luminosities to stellar mass. Separate luminosity functions are obtained for the two distributions. The red distribution has a more luminous characteristic magnitude and a shallower faint-end slope (M^*=-21.5, alpha=-0.8) compared to the blue distribution (alpha=-1.3 depending on the parameterization). These are approximately converted to galaxy stellar mass functions. The red distribution galaxies have a higher number density per magnitude for masses greater than about 3x10^10 M_solar. Using a simple merger model, we show that the differences between the two functions are consistent with the red distribution being formed from major galaxy mergers. TI - Quantifying the bimodal color-magnitude distribution of galaxies KW - cmr KW - goodintroduction KW - sloan AU - Baldry, IK AU - Glazebrook, K AU - Brinkmann, J AU - Ivezic, Z AU - Lupton, RH AU - Nichol, RC AU - Szalay, AS PY - 2003/Sep/25/ UR - http://arxiv.org/abs/astro-ph/0309710 ER -