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Register a new userThe Morphological Type Dependence of K-band Luminosity Functions
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Differential 2.2um (K-band) luminosity functions are presented for a complete sample of 1570 nearby Vgsr < 3000 km/s, where Vgsr is the velocity measured with respect to the Galactic standard of rest), bright (K < 10 mag), galaxies segregated by visible morphology. The K-band luminosity function for late-type spirals follows a power law that rises towards low luminosities whereas the K-band luminosity functions for ellipticals, lenticulars and bulge-dominated spirals are peaked with a fall off at both high and low luminosities. However, each morphological type (E, S0, S0/a-Sab, Sb-Sbc, Sc-Scd) contributes approximately equally to the overall K-band luminosity density in the local universe, and by inference, the stellar mass density as well.
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Differential K-band luminosity functions (LFs) are presented for a complete sample of 1613 nearby bright galaxies segregated by visible morphology. The LF for late-type spirals follows a power law that rises towards low luminosities whereas the LFs for ellipticals, lenticulars and bulge-dominated spirals are peaked and decline toward both higher and lower luminosities. Each morphological type (E, S0, S0/a-Sab, Sb-Sbc, Sc-Scd) contributes approximately equally to the overall K-band luminosity density of galaxies in the local universe. Type averaged bulge/disk ratios are used to subtract the disk component leading to the prediction that the K-band LF for bulges is bimodal with ellipticals dominating the high luminosity peak, comprising 60% of the bulge luminosity density in the local universe with the remaining 40% contributed by lenticulars and the bulges of spirals. Overall, bulges contribute 30% of the galaxy luminosity density at K in the local universe with spiral disks making up the remainder. If bulge luminosities indicate central black hole masses, then our results predict that the black hole mass function is also bimodal.
K band luminosity functions (LFs) of three, massive, high redshift clusters of galaxies are presented. The evolution of K*, the characteristic magnitude of the LF, is consistent with purely passive evolution, and a redshift of forma tion z = 1.5-2.
There is growing evidence that every galaxy with a considerable spheroidal component hosts a supermassive black hole (SMBH) at its center. Strong correlations between the SMBH and the spheroidal component suggest a physical connection through a coevolutionary scenario. For very massive galaxies a merger-driven scenario is preferred, resulting in elliptical galaxies. In the nearby universe, we find many disk galaxies, showing no signs of recent interaction. Alternative secular evolutionary scenarios for such galaxies involve internal triggers like bars and spiral arms or minor mergers. We analyze a sample of 99 nearby galaxies (0.02 < z < 0.06) from the Hamburg/ESO survey in order to get insight into structural and dynamical properties of the hosts to trace the origin of the bulge-SMBH correlation. In this work, we first collect images of sample members to get an impression of the morphological distribution in the sample. In a second step, we start to analyze sensitive, high resolution near-infrared images of 20 galaxies, performing aperture photometry and bulge-disk decomposition with the BUDDA code. We find an unexpected high fraction of barred galaxies and many other structural peculiarities.
We measured the K-band luminosity function using a complete sample of 4192 morphologically-typed 2MASS galaxies with 7 < K < 11.25 mag spread over 2.12 str. Early-type (T < -0.5) and late-type (T > -0.5) galaxies have similarly shaped luminosity functions, alpha_e=-0.92+/-0.10 and alpha_l=-0.87+/-0.09. The early-type galaxies are brighter, M_*e=-23.53+/-0.06 mag compared to M_*l=-22.98pm0.06 mag, but less numerous, n_*e=(0.0045+/-0.0006)h^3/Mpc^3 compared to n_*l=(0.0101+/-0.0013)h^3/Mpc^3 for H_0=100h km/s Mpc, such that the late-type galaxies slightly dominate the K-band luminosity density, j_late/j_early=1.17+/-0.12. Our morphological classifications are internally consistent, consistent with previous classifications and lead to luminosity functions unaffected by the estimated uncertainties in the classifications. These luminosity functions accurately predict the K-band number counts and redshift distributions for K < 18 mag, beyond which the results depend on galaxy evolution and merger histories.
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