2,245 research outputs found
Impact of foregrounds on Cosmic Microwave Background maps
We discuss the possible impact of astrophysical foregrounds on three recent
exciting results of Cosmic Microwave Background (CMB) experiments: the WMAP
measurements of the temperature-polarization (TE) correlation power spectrum,
the detection of CMB polarization fluctuations on degree scales by the DASI
experiment, and the excess power on arcminute scales reported by the CBI and
BIMA groups. A big contribution from the Galactic synchrotron emission to the
TE power spectrum on large angular scales is indeed expected, in the lower
frequency WMAP channels, based on current, albeit very uncertain, models; at
higher frequencies the rapid decrease of the synchrotron signal may be, to some
extent, compensated by polarized dust emission. Recent measurements of
polarization properties of extragalactic radio sources at high radio frequency
indicate that their contamination of the CMB polarization on degree scales at
30 GHz is substantially below the expected CMB E-mode amplitude. Adding the
synchrotron contribution, we estimate that the overall foreground contamination
of the signal detected by DASI may be significant but not dominant. The excess
power on arc-min scales detected by the BIMA experiment may be due to
galactic-scale Sunyaev-Zeldovich effects, if the proto-galactic gas is heated
to its virial temperature and its cooling time is comparable to the Hubble time
at the epoch of galaxy formation. A substantial contamination by radio sources
of the signal reported by the CBI group on scales somewhat larger than BIMA's
cannot be easily ruled out.Comment: 10 pages, 5 figures, to appear in proc. int. conf. "Thinking,
Observing and Mining the Universe", Sorrento, Sept. 200
A dark matter interpretation for the ARCADE excess?
The ARCADE 2 Collaboration has recently measured an isotropic radio emission
which is significantly brighter than the expected contributions from known
extra-galactic sources. The simplest explanation of such excess involves a
"new" population of unresolved sources which become the most numerous at very
low (observationally unreached) brightness. We investigate this scenario in
terms of synchrotron radiation induced by WIMP annihilations or decays in
extragalactic halos. Intriguingly, for light-mass WIMPs with thermal
annihilation cross-section, and fairly conservative clustering assumptions, the
level of expected radio emission matches the ARCADE observations.Comment: 5 pages, 3 figures. v2: one benchmark model added, comments and
references expanded, to appear in PR
The Planck Surveyor mission: astrophysical prospects
Although the Planck Surveyor mission is optimized to map the cosmic microwave
background anisotropies, it will also provide extremely valuable information on
astrophysical phenomena. We review our present understanding of Galactic and
extragalactic foregrounds relevant to the mission and discuss on one side,
Planck's impact on the study of their properties and, on the other side, to
what extent foreground contamination may affect Planck's ability to accurately
determine cosmological parameters. Planck's multifrequency surveys will be
unique in their coverage of large areas of the sky (actually, of the full sky);
this will extend by two or more orders of magnitude the flux density interval
over which mm/sub-mm counts of extragalactic sources can be determined by
instruments already available (like SCUBA) or planned for the next decade (like
the LSA-MMA or the space mission FIRST), which go much deeper but over very
limited areas. Planck will thus provide essential complementary information on
the epoch-dependent luminosity functions. Bright radio sources will be studied
over a poorly explored frequency range where spectral signatures, essential to
understand the physical processes that are going on, show up. The
Sunyaev-Zeldovich effect, with its extremely rich information content, will be
observed in the direction of a large number of rich clusters of Galaxies.
Thanks again to its all sky coverage, Planck will provide unique information on
the structure and on the emission properties of the interstellar medium in the
Galaxy. At the same time, the foregrounds are unlikely to substantially limit
Planck's ability to measure the cosmological signals. Even measurements of
polarization of the primordial Cosmic Microwave background fluctuations appear
to be feasible.Comment: 20 pages, Latex (use aipproc2.sty, aipproc2.cls, epsfig.sty), 10
PostScript figures; invited review talk, Proc. of the Conference: "3 K
Cosmology", Roma, Italy, 5-10 October 1998, AIP Conference Proc, in press
Note: Figures 6 and 7 have been replaced by new and correct version
Integration of cranial base and face in growing subject
Background: many papers investigate the role of the cranial base in facial development, but the results are not in agreement. This can be due to a difference between the central and lateral parts of the cranial base. The aim of the present study is to evaluate the relationship between the central and the lateral cranial base and the facial skeleton in pre-pubertal peak subjects and at the end of growth. Material/Methods: a total sample of 52 latero-lateral cranial teleradiographs were analyzed. To test the correlation between structures, the "Partial Least Square" analysis was performed. Geometric morphometric analysis were applied and partial least square analysis was used to test correlation. Integration was studied removing the effect of allometry. Results: facial skeleton has no significant relation with central cranial base. Facial skeleton has significant relationships with the lateral portion of the cranial base. This relationship is higher in the post-peak phase of growth. Conclusion: the Integration between facial structures and cranial base is significant. The Spatial orientation and shape of the facial structures are both influenced by cranial base. This is mainly due to the lateral portion of cranial base
A snapshot of knowledge about oral cancer in italy: A 505 person survey
Objectives: Patients’ knowledge about oral squamous cell carcinoma (OSCC) plays an important role in primary prevention, early diagnosis, and prognosis and survival rate. The aim of this study was to assess OSCC awareness attitudes among general population in order to provide information for educational interventions. Methods: A survey delivered as a web-based questionnaire was submitted to 505 subjects (aged from 18 to 76 years) in Italy, and the answers collected were statistically analyzed. Information was collected about existence, incidence, features of lesions, risk factors of oral cancer, and self-inspection habits, together with details about professional reference figures and preventive behaviors. Results: Chi-square tests of independence with adjusted standardized residuals highlighted correlations between population features (age, gender, educational attainment, provenance, medical relationship, or previous diagnoses of oral cancer in family) and knowledge about oral cancer. Conclusions: Knowledge about OSCC among the Italian population is limited, and it might be advisable to implement nudging and sensitive customized campaigns in order to promote awareness and therefore improve the prognosis of this disease
Dynamical and photometric imprints of feedback processes on the early evolution of E/S0 galaxies
We show that the observed Velocity Dispersion Function of E/S0 galaxies
matches strikingly well the distribution function of virial velocities of
massive halos virializing at z > 1.5, as predicted by the standard hierarchical
clustering scenario in a \LambdaCDM cosmology, for a constant ratio sigma/V_vir
= 0.55 \pm 0.05, close to the value expected at virialization if it typically
occurred at z > 3. This strongly suggests that dissipative processes and later
merging events had little impact on the matter density profile. Adopting the
above sigma/V_vir ratio, the observed relationships between photometric and
dynamical properties which define the fundamental plane of elliptical galaxies,
such as the luminosity-sigma (Faber-Jackson) and the luminosity-effective
radius relations, as well as the M_BH-sigma relation, are nicely reproduced.
Their shapes turn out to be determined by the mutual feedback of star-formation
(and supernova explosions)and nuclear activity, along the lines discussed by
Granato et al. (2004). To our knowledge, this is the first semi-analytic model
for which simultaneous fits of the fundamental plane relations and of the
epoch-dependent luminosity function of spheroidal galaxies have been presented.Comment: 14 pages, 6 figures, submitted to Ap
The suggested structure of final demand shock for sectoral labour digital skills
International data seem to confirm that countries with a relative abundancy of highly-skilled labour with digital competences grow faster than others. For this reason, digital competences and skills in general are progressively assuming a central role in labour market policies. In this article, we show the potential of the disaggregated multisectoral analysis with the macro multipliers approach as a tool of economic policy. Such analyses allow identifying a set of endogenous policies in which specific objectives do not clash with growth objectives. The identification and the quantification of the macro multipliers is based on an extended multi-industry, multi-factor and multi-sector model, which accounts for the representation of the income circular flow as in the social accounting matrix (SAM). The SAM constructed for this exercise allows for a proper disaggregation of the labour factor by formal educational attainment, digital competences and gender for the case of Italy
Black hole and galaxy coevolution from continuity equation and abundance matching
We investigate the coevolution of galaxies and hosted supermassive black holes (BHs) throughout the history of the universe by a statistical approach based on the continuity equation and the abundance matching technique. Specifically, we present analytical solutions of the continuity equation without source terms to reconstruct the supermassive BH mass function from the active galactic nucleus (AGN) luminosity functions. Such an approach includes physically motivated AGN light curves tested on independent data sets, which describe the evolution of the Eddington ratio and radiative efficiency from slim- to thin-disk conditions. We nicely reproduce the local estimates of the BH mass function, the AGN duty cycle as a function of mass and redshift, along with the Eddington ratio function and the fraction of galaxies with given stellar mass hosting an AGN with given Eddington ratio. We exploit the same approach to reconstruct the observed stellar mass function at different redshift from the ultraviolet and far-IR luminosity functions associated with star formation in galaxies. These results imply that the build-up of stars and BHs in galaxies occurs via in situ processes, with dry mergers playing a ☉marginal role at least for stellar masses ≤ 3 × 1011 M☉ and BH masses 109 M where the statistical data are more secure and less biased by systematic errors. In addition, we develop an improved abundance matching technique to link the stellar and BH content of galaxies to the gravitationally dominant dark matter (DM) component. The resulting relationships constitute a testbed for galaxy evolution models, highlighting the complementary role of stellar and AGN feedback in the star formation process. In addition, they may be operationally implemented in numerical simulations to populate DM halos or to gauge subgrid physics. Moreover, they may be exploited to investigate the galaxy/AGN clustering as a function of redshift, mass, and/or luminosity. In fact, the clustering properties of BHs and galaxies are found to be in full agreement with current observations, thus further validating our results from the continuity equation. Finally, our analysis highlights that (i) the fraction of AGNs observed in the slim-disk regime, where most of the BH mass is accreted, increases with redshift; and (ii) already at z\gtrsim 6$ a substantial amount of dust must have formed over timescales 108 yr in strongly star-forming galaxies, making these sources well within the reach of ALMA surveys in (sub)millimeter bands
A 20 GHz bright sample for {\delta} > +72{\deg}: I. Catalogue
During 2010-2011, the Medicina 32-m dish hosted the 7-feed 18-26.5 GHz
receiver built for the Sardinia Radio Telescope, with the goal to perform its
commissioning. This opportunity was exploited to carry out a pilot survey at 20
GHz over the area for {\delta} > + 72.3{\deg}. This paper describes all the
phases of the observations, as they were performed using new hardware and
software facilities. The map-making and source extraction procedures are
illustrated. A customised data reduction tool was used during the follow-up
phase, which produced a list of 73 confirmed sources down to a flux density of
115 mJy. The resulting catalogue, here presented, is complete above 200 mJy.
Source counts are in agreement with those provided by the AT20G survey. This
pilot activity paves the way to a larger project, the K-band Northern Wide
Survey (KNoWS), whose final aim is to survey the whole Northern Hemisphere down
to a flux limit of 50 mJy (5{\sigma}).Comment: 10 pages, 10 figures. Accepted by MNRA
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