1,987 research outputs found
Super-massive Black Hole Demography: the Match between the Local and Accreted Mass Functions
We have performed a detailed analysis of the local super-massive black-hole
(SMBH) mass function based on both kinematic and photometric data and derived
an accurate analytical fit in the range 10^6 <= (M_BH/M_sun) <= 5*10^9. We find
a total SMBH mass density of (4.2+/-1.1)*10^5 M_sun/Mpc^3, about 25% 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 AGNs, we
have studied the accretion history of the SMBH population. If most of the
accretion happens at constant \dot{M_BH}/M_BH 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 \epsilon ~10%. The analysis of the accretion history
highlights that the most massive BHs accreted their mass faster and at higher
redshifts (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 \epsilon ~0.09(+0.04,-0.03) and the Eddington
ratio \lambda=L/L_Edd \~0.3(+0.3,-0.1) (68% 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
M_BH(z=0) ~10^6 M_sun to ~0.3 Gyr for M_BH(z=0) >= 10^9 M_sun. The mass
accreted during luminous phases is >= 25-30% even if we assume extreme values
of \epsilon (\epsilon \~0.3-0.4). An unlikely fine tuning of the parameters
would be required to account for the local SMBH mass function accomodating a
dominant contribution from 'dark' BH growth (due, e.g., to BH coalescence).Comment: 12 pages, 14 figures, accepted for publication in MNRAS, minor
changes following referee's comment
The Baryonic Mass vs. Dark Halo Mass Relationship in Galaxies. the imprint of large energy feedbacks and of the inefficiency of the cosmological star formation
Extragalactic Source Counts and Contributions to the Anisotropies of the Cosmic Microwave Background. Predictions for the Planck Surveyor mission
We present predictions for the counts of extragalactic sources, the
contributions to fluctuations and their spatial power spectrum in each channel
foreseen for the Planck Surveyor (formerly COBRAS/SAMBA) mission. The
contribution to fluctuations due to clustering of both radio and far--IR
sources is found to be generally small in comparison with the Poisson term;
however the relative importance of the clustering contribution increases and
may eventually become dominant if sources are identified and subtracted down to
faint flux limits. The central Planck frequency bands are expected to be
``clean'': at high galactic latitude (|b|>20), where the reduced galactic noise
does not prevent the detection of the extragalactic signal, only a tiny
fraction of pixels is found to be contaminated by discrete extragalactic
sources. Moreover, removal of contaminating signals is eased by the substantial
difference between their power spectrum and that of primordial fluctuations.Comment: 10 pages, Latex, mn.sty, 8 figures included, MNRAS, in the press.
Minor changes in the text. Sections 3.1 and 3.2 have been expanded. Source
counts in Table 2 have been slightly changed. Figure 1,2,7 and 8 have been
replaced by new version
A mini-invasive surgical technique for Carlevale IOL implantation: case series study and description of concomitant surgery
Purpose: To examine the feasibility and outcomes of a modified technique for the implantation of scleral fixated Carlevale intraocular lens (IOL) (I71 FIL SSF. Soleko IOL Division, Pontecorvo, Italy), and to analyze the occurrence of adverse events. Methods: This is a retrospective observational study conducted revising patients charts from 2018 to 2023. Thirty-five eyes of 33 patients were included. Patients requiring IOL explantation had either IOL dislocation or opacification. The implantation of the Carlevale IOL was performed with the subconjunctival positioning of the anchors without any scleral flap. All maneuvers were performed transconjunctivally. The anatomical outcomes considered were IOL positioning, and the absence of postoperative complications. The functional outcomes analyzed were best correctedvisual acuity (BCVA) and refraction. Results: In all the cases, the IOL was well positioned and centered postoperatively. No cases of conjunctival erosion were recorded. The best corrected visual acuity (BCVA) was 0.9±0.6 logMar (mean±standard deviation) preoperatively and 0.5±0.5 logMar (mean±standard deviation) postoperatively. The mean preoperative spherical equivalent was +6.8±7.7 dioptres, while postoperatively it was -1.1±1.6 dioptres. The most frequent procedure associated to secondary IOL implantation was posterior vitrectomy (25 eyes, 71.4%), which was performed with 25-gauge transconjunctival cannulas in the ciliary sulcus. The follow-up period was 24.5±16.9 months (mean±standard deviation). Conclusion: The described mini-invasive technique for Carlevale IOL implantation is safe and effective. It can be recommended either as a stand-alone operation or associated to concurrent surgical procedures
Axillary dissection vs. No axillary dissection in breast cancer patients with positive sentinel lymph node: A single institution experience
A Physical Model for Co-evolution of QSOs and of their Spheroidal Hosts
At variance with most semi-analytic models, in the Anti-hierarchical Baryon
Collapse scenario (Granato et al. 2001, 2004) the main driver of the galaxy
formation and evolution is not the merging sequence but are baryon processes.
This approach emphasizes, still in the framework of the hierarchical clustering
paradigm for dark matter halos, feedback processes from supernova explosions
and from active nuclei, that tie together star formation in spheroidal galaxies
and the growth of black holes at their centers. We review some recent results
showing the remarkably successful predictive power of this scenario, which
allows us to account for the evolution with cosmic time of a broad variety of
properties of galaxies and active nuclei, which proved to be very challenging
for competing models.Comment: Invited talk at the Specola Vaticana Workshop on "AGN and Galaxy
Evolution", Castel Gandolfo, 3-6 October 2005, 10 pages, 2 figure
From First Galaxies to QSOs: feeding the baby monsters
We present a physical model for the coevolution of massive spheroidal
galaxies and active nuclei at their centers. Supernova heating is increasingly
effective in slowing down the star formation and in driving gas outflows in
smaller and smaller dark matter halos. Thus the more massive protogalaxies
virializing at early times are the sites of faster star formation. The
correspondingly higher radiation drag causes a faster angular momentum loss by
the gas and induces a larger accretion rate onto the central black hole. In
turn, the kinetic energy of the outflows powered by the active nuclei can
unbind the residual gas in a time shorter for larger halos. The model accounts
for a broad variety of dynamical, photometric and metallicity properties of
early-type galaxies, for the M_BH -- \sigma relation and for the local
supermassive black-hole mass function.Comment: 6 pages, contributed paper to Proceedings of the Conference on
"Growing Black Holes" held in Garching, Germany, on June 21-25, 2004, edited
by A. Merloni, S. Nayakshin and R. Sunyaev, Springer-Verlag series of "ESO
Astrophysics Symposia
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