We present a physically motivated model for the early coevolution of massive spheroidal galaxies and active nuclei at their centers. Within dark matter halos, forming at the rate predicted by the canonical hierarchical clustering scenario, the gas evolution is controlled by gravity, radiative cooling, and heating by feedback from supernovae and from the growing active nucleus. Supernova heating is increasingly effective with decreasing binding energy in slowing down the star formation and in driving gas outflows. The more massive protogalaxies virializing at earlier times are thus the sites of the faster star formation. The correspondingly higher radiation drag fastens the angular momentum loss by the gas, resulting in a larger accretion rate onto the central black hole. In turn, the kinetic energy carried by outflows driven by active nuclei can unbind the residual gas, thus halting both the star formation and the black hole growth, in a time again shorter for larger halos. For the most massive galaxies the gas unbinding time is short enough for the bulk of the star formation to be completed before Type Ia supernovae can substantially increase the Fe abundance of the interstellar medium, thus accounting for the -enhancement seen in the largest galaxies. The feedback from supernovae and from the active nucleus also determines the relationship between the black hole mass and the mass, or the velocity dispersion, of the host galaxy, as well as the black hole mass function. In both cases the model predictions are in excellent agreement with the observational data. Coupling the model with GRASIL (Silva et al. 1998), the code computing in a selfconsistent way the chemical and spectrophotometric evolution of galaxies over a very wide wavelength interval, we have obtained predictions in excellent agreement with observations for a number of observables that proved to be extremely challenging for all the current semianalytic models, including the submillimeter counts and the corresponding redshift distributions, and the epoch-dependent K-band luminosity function of spheroidal galaxies.

We use a homogeneous sample of about 1100 optical and radio rotation curves (RCs) and relative surface photometry to investigate the main mass structure properties of spirals, over a range of 6 magnitudes and out to ∼ < 1.5 and 2 optical radii (for the optical and radio data, respectively). We definitely confirm the strong dependence on luminosity for both the profile and the amplitude of RCs claimed by Persic & Salucci (1991). Spiral RCs show the striking feature that a single global parameter, e.g. luminosity, dictates the rotation velocity at any radius for any object, so unveiling the existence of a Universal RC. At high luminosities, there is a slight discrepancy between the profiles of RCs and those predicted from the luminous matter (LM) distributions: this implies a small, yet detectable, amount of dark matter (DM). At low luminosities, the failure of the LM prediction is much more severe, and the DM is the only relevant mass component. We show that the Universal RC implies a number of scaling properties between dark and luminous galactic structure parameters: (a) the DM/LM mass ratio scales inversely with luminosity; (b) the central halo density scales as L −0.7 ; (c) the halo core radius is comparable to the optical radius, but shrinks for low luminosities; (d) the total halo mass scales as L 0.5 . Such scaling properties can be represented as a curve in the (luminosity)-(DM/LM mass ratio)-(DM core radius)-(DM central density) space, which provides a geometrical description of the tight coupling between the dark and the luminous matter in spiral galaxies.

We present the HI data for 5 spiral galaxies that, along with their Halpha rotation curves, are used to derive the distribution of dark matter within these objects. A new method for extracting rotation curves from HI data cubes is presented; this takes into account the existence of a warp and minimises projection effects. The rotation curves obtained are tested by taking them as input to construct model data cubes that are compared to the observed ones: the agreement is excellent. On the contrary, the model data cubes built using rotation curves obtained with standard methods, such as the first-moment analysis, fail the test. The HI rotation curves agree well with the Halpha data, where they coexist. Moreover, the combined Halpha + HI rotation curves are smooth, symmetric and extended to large radii. The rotation curves are decomposed into stellar, gaseous and dark matter contributions and the inferred density distribution is compared to various mass distributions: dark haloes with a central density core, $\Lambda$ Cold Dark Matter ($\Lambda$CDM) haloes (NFW, Moore profiles), HI scaling and MOND. The observations point to haloes with constant density cores of size $r_{core} \sim r_{opt}$ and central densities scaling approximately as $\rho_0 \propto r_{core}^{-2/3}$. $\Lambda$CDM models (which predict a central cusp in the density profile) are in clear conflict with the data. HI scaling and MOND cannot account for the observed kinematics: we find some counter-examples.Comment: 23 pages, 15 figures, MNRAS accepted. Comments welcome. Version with Figs. 1 and 3 at full resolution available at http://www.astro.uni-bonn.de/~ggentile/paper_highres.ps.g

We have performed a detailed analysis of the local supermassive black hole (SMBH) mass function based on both kinematic and photometric data and we have derived an accurate analytical fit in the range 106≤MBH/M⊙≤ 5 × 109. We find a total SMBH mass density of (4.2 ± 1.1) × 105 M⊙ Mpc−3, about 25 per cent of which is contributed by SMBHs residing in bulges of late‐type galaxies. Exploiting up‐to‐date luminosity functions of hard X‐ray and optically selected active galactic nuclei (AGNs), we have studied the accretion history of the SMBH population. If most of the accretion occurs at constant , as in the case of Eddington‐limited accretion and consistent with recent observational estimates, the local SMBH mass function is fully accounted for by mass accreted by X‐ray selected AGNs, with bolometric corrections indicated by current observations and a standard mass‐to‐light conversion efficiency ε≃ 10 per cent. The analysis of the accretion history highlights that the most massive BHs (associated with bright optical quasi‐stellar objects) accreted their mass faster and at higher redshifts (typically at z > 1.5), while the lower‐mass BHs responsible for most of the hard X‐ray background have mostly grown at z < 1.5. The accreted mass function matches the local SMBH mass function if, during the main accretion phases, ε≃ 0.09 (+0.04, −0.03) and the Eddington ratio λ=L/LEdd≃ 0.3 (+0.3, −0.1) (68 per cent confidence errors). The visibility time, during which AGNs are luminous enough to be detected by the currently available X‐ray surveys, ranges from ≃0.1 Gyr for present‐day BH masses M0BH≃ 106 M⊙ to ≃0.3 Gyr for M0BH≥ 109 M⊙. The mass accreted during luminous phases is ≥25–30 per cent even if we assume extreme values of ε(ε≃ 0.3–0.4). An unlikely fine tuning of the parameters would be required to account for the local SMBH mass function accommodating a dominant contribution from ‘dark’ BH growth (due, for example, to BH coalescence).

We confirm and extend the recent finding that the central surface density r_0*rho_0 galaxy dark matter halos, where r_0 and rho_0 are the halo core radius and central density, is nearly constant and independent of galaxy luminosity. Based on the co-added rotation curves of about 1000 spiral galaxies, mass models of individual dwarf irregular and spiral galaxies of late and early types with high-quality rotation curves and, galaxy-galaxy weak lensing signals from a sample of spiral and elliptical galaxies, we find that log(r_0*rho_0) = 2.15 +- 0.2, in units of log(Msol/pc^2). We also show that the observed kinematics of Local Group dwarf spheroidal galaxies are consistent with this value. Our results are obtained for galactic systems spanning over 14 magnitudes, belonging to different Hubble Types, and whose mass profiles have been determined by several independent methods. In the same objects, the approximate constancy of rho_0*r_0 is in sharp contrast to the systematical variations, by several orders of magnitude, of galaxy properties, including rho_0 and central stellar surface density.Comment: Accepted for publication in MNRAS. 9 pages, 4 figure