The 2 MASS Luminosity , Velocity , and
نویسندگان
چکیده
The velocity function (VF) of galaxies is analogous to the luminosity function (LF), but a more direct tool for comparing observations and theory. The 2MASS LF is calculated here for a local sample of 4000 galaxies, and the VF is derived from a 1000 galaxy subsample drawn from it. The observed VF follows a Schechter functional form. All current analytical, semi-analytical, and numerical galaxy formation models predict power-law (or nearly so) shapes for the VF, and hence cannot reproduce the observations. It remains an open challenge for any galaxy formation model to explain the observed VF.
منابع مشابه
LINEAR PULSATION CHARACTERISTICS OF MIRA VARIABLE STARS
The linear adiabatic pulsation-periods of Mira variable stars have been derived. Approximately 2701[1]models were calculated for M = 0.7 MΘ to 2 MΘ stars with radii from 180 RΘ to 340 RΘ and luminosities from 2800 LΘ to 10,000 LΘ. The chemical composition of all models is (X,Z) = (0.7,0.02). From the result of this study, linear relations on Luminosity-Period-Mass relationship and luminosity-pe...
متن کاملTales within Tales and Cutoffs within Cutoffs: What Sets the Mass Scale for Galaxies?
Please answer “yes” or “no”: 1. Does the mass function for clusters of galaxies cut off exponentially? 2. Does the luminosity function for galaxies cut off exponentially? 3. Is the dependence of virial velocity on galaxy luminosity a power law? 4. Does the velocity function for galaxies cut off exponentially?
متن کاملمدلی برای ساختار دینامیکی و یونیدگی سحابی سیاره نمای (418 IC)
The interacting two winds model and a spherical density distribution function are introduced to study the dynamical and ionization structure of the planetary nebula IC 418. A fast wind with a mechanical luminousity 2/34×1034erg.s-1 of interacts with a super wind with a mass-loss rate of 2×10-5M(°)yr-1 and a velocity of 10 , and produces a dense and luminous medium. In this model, the exp...
متن کاملDynamical Constraints on Disk Galaxy Formation
The rotation curves of disk galaxies exhibit a number of striking regularities. The amplitude of the rotation is correlated with luminosity (Tully-Fisher), the shape of the rotation curve is well predicted by the luminous mass distribution, and the magnitude of the mass discrepancy increases systematically with decreasing centripetal acceleration. These properties indicate a tight connection be...
متن کاملThe radio luminosity, black hole mass and Eddington ratio for quasars from the Sloan Digital Sky Survey
We investigate the MBH−σ∗ relation for radio-loud quasars with redshift z < 0.83 in Data Release 3 of the Sloan Digital Sky Survey (SDSS). The sample consists of 3772 quasars with better model of Hβ and [O III] lines and available radio luminosity, including 306 radio-loud quasars, 3466 radio-quiet quasars with measured radio luminosity or upper-limit of radio luminosity (181 radio-quiet quasar...
متن کاملar X iv : a st ro - p h / 06 03 73 2 v 2 10 A pr 2 00 6 Velocity dispersion , mass and the luminosity function of the fossil cluster RX J 1416 .
We study the properties of the fossil cluster RX J1416.4+2315 through g’ and i’-band imaging and spectroscopy of 25 member galaxies. The system is at a mean redshift of 0.137 and has a velocity dispersion of 584 km s−1. Superimposed onto one quadrant of the cluster field there is a group of five galaxies at a mean redshift of 0.131, which, if included as part of the cluster, increases the veloc...
متن کامل