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Search Results: 1 - 10 of 144356 matches for " B. Caccianiga "
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Optical Spectroscopy of the unusual galaxy J2310-43
A. Caccianiga,T. Maccacaro
Physics , 1997, DOI: 10.1086/118652
Abstract: We present and discuss new spectroscopic observations of the unusual galaxy J2310-43. The observations cover a wide wavelength range, from 3700 A to 9800 A allowing the study of both the regions where H alpha and the Ca II ``contrast'' are expected. No evidence for H alpha in emission is found and we thus confirm the absence of emission lines in the spectrum of J2310-43, ruling out the possibility that it may host a Seyfert nucleus. The CaII break is clearly detected and the value of the contrast (38 +/-4 %) is intermediate between that of a typical elliptical galaxy (about 50 %) and that of a BL Lac object (<25 %). This result imposes limits on the intensity of a possible non-stellar continuum and, in the light of the radio and X-ray loudness of the source, draws further attention to the problem of the recognition of a BL Lac object. Objects like J2310-43 may be more common than previously recognized, and begin to emerge in surveys of radio-emitting X-ray sources.
The relationship between [OIII]5007A equivalent width and obscuration in AGN
A. Caccianiga,P. Severgnini
Physics , 2011, DOI: 10.1111/j.1365-2966.2011.18838.x
Abstract: In this paper we study the relationship between the equivalent width (EW) of the [OIII]5007A narrow emission line in AGN and the level of obscuration. To this end, we combine the results of a systematic spectral analysis, both in the optical and in the X-rays, on a statistically complete sample of ~170 X-ray selected AGN from the XMM-Newton Bright Serendipitous Source sample (XBS). We find that the observed large range of [OIII]5007A equivalent widths observed in the sample (from a few A up to 500A) is well explained as a combination of an intrinsic spread, probably due to the large range of covering factors of the Narrow Line Region, and the effect of absorption. The intrinsic spread is dominant for EW below 40-50A while absorption brings the values of EW up to ~100-150A, for moderate levels of absorption (AV~0.5-2 mag) or up to ~500A for AV>2 mag. In this picture, the absorption has a significant impact on the observed EW also in type~1 AGN. Using numerical simulations we find that this model is able to reproduce the [OIII]5007A EW distribution observed in the XBS sample and correctly predicts the shape of the EW distribution observed in the optically selected sample of QSO taken from the SDSS survey.
GPS-based CERN-LNGS time link for Borexino
B. Caccianiga,P. Cavalcante,G. Cerretto,H. Esteban,G. Korga,M. Misiaszek,M. Orsini,M. Pallavicini,V. Pettiti,C. Plantard,A. Razeto
Physics , 2012,
Abstract: We describe the design, the equipment, and the calibration of a new GPS based time link between CERN and the Borexino experiment at the Gran Sasso Laboratory in Italy. This system has been installed and operated in Borexino since March 2012, and used for a precise measurement of CNGS muon neutrinos speed in May 2012. The result of the measurement will be reported in a different letter.
Heavily obscured AGN with SIMBOL-X
R. Della Ceca,A. Caccianiga,P. Severgnini
Physics , 2009, DOI: 10.1063/1.3149417
Abstract: By comparing an optically selected sample of narrow lines AGN with an X-ray selected sample of AGN we have recently derived an estimate of the intrinsic (i.e. before absorption) 2-10 keV luminosity function (XLF) of Compton Thick AGNs. We will use this XLF to derive the number of Compton Thick AGN that will be found in the SIMBOL-X survey(s).
A new technique to efficiently select Compton-thick AGN
P. Severgnini,A. Caccianiga,R. Della Ceca
Physics , 2012, DOI: 10.1051/0004-6361/201118417
Abstract: We present a new efficient diagnostic method, based on mid-infrared and X-ray data, to select local (z<0.1) Compton-thick (CT) AGN with the aim of estimating their surface and space density. We define a region in the X-ray/IR vs. HR plane associated to CT AGN, i.e. F(2-12keV)/F25nu25<0.02 and HR>-0.2. We build up a sample of 43 CT AGN candidates using data from IRAS-PSC and 2XMM catalogue. In order to test the efficiency of the proposed method in selecting CT AGN we use the results of the X-ray spectral analysis performed on all the sources of our sample. After taking into account the different selection effects, we have estimated the number of CT in the local Universe and their density down to the IRAS flux limit of F25=0.5Jy. We find that the diagnostic plot proposed here is an efficient method to select Compton-thick AGN in the nearby Universe since ~84% of the sources populating the proposed CT region are actually CT AGN. Twenty percent are newly-discovered CT AGN. We then estimate the surface density of CT AGN down to the IRAS PSC catalogue flux limit (F25=0.5Jy) that turns out to be ~3e-3 src deg-2. After estimating an equivalent IR-hard X-ray limiting flux, we compare our result with those found with SWIFT-BAT. We find that the surface density derived here is a factor 4 above the density computed in the hard X-ray surveys. This difference is ascribed, at least in part, to a significant contribution (~60-90%) of the star-forming activity to the total 25 mic emission for the sources in our sample. By considering only the 25 mic AGN emission, we estimate a surface density of CT AGN which is consistent with the results found by hard X-ray surveys. Finally, we estimated the co-moving space density of CT AGN with intrinsic LX>1e43 erg s-1 (0.004
The CLASS BL Lac sample: The Radio Luminosity Function
M. J. M. Marcha,A. Caccianiga
Physics , 2013, DOI: 10.1093/mnras/stt065
Abstract: This paper presents a new sample of BL Lac objects selected from a deep (30 mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey, henceforth CBS). The sample is one of the largest well defined samples in the low power regime with a total of 130 sources of which 55 satisfy the 'classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the Radio Luminosity Function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the LF which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study we extend for the first time the BL Lac RLF down to very low radio powers ~10^22 W/Hz, ie, two orders of magnitude below the RLF currently available in the literature. In the process we confirm the importance of adopting a broader, and more physically meaningful set of classification criteria to avoid the systematic missing of low luminosity BL Lacs. Thanks to the good statistics we confirm the existence of weak but significant positive cosmological evolution for the BL Lac population, and we detect, for the first time the flattening of the RLF at ~10^25 W/Hz in agreement with the predictions of the beaming model.
High sensitivity double beta decay study of 116-Cd and 100-Mo with the BOREXINO Counting Test Facility (CAMEO project)
G. Bellini,B. Caccianiga,M. Chen,F. A. Danevich,M. G. Giammarchi,V. V. Kobychev,B. N. Kropivyansky,E. Meroni,L. Miramonti,A. S. Nikolayko,L. Oberauer,O. A. Ponkratenko,V. I. Tretyak,S. Yu. Zdesenko,Yu. G. Zdesenko
Physics , 2000, DOI: 10.1007/s100520100594
Abstract: The unique features (super-low background and large sensitive volume) of the CTF and BOREXINO set ups are used in the CAMEO project for a high sensitivity study of 100-Mo and 116-Cd neutrinoless double beta decay. Pilot measurements with 116-Cd and Monte Carlo simulations show that the sensitivity of the CAMEO experiment (in terms of the half-life limit for neutrinoless double beta decay) is (3-5) 10^24 yr with a 1 kg source of 100-Mo (116-Cd, 82-Se, and 150-Nd) and about 10^26 yr with 65 kg of enriched 116-CdWO_4 crystals placed in the liquid scintillator of the CTF. The last value corresponds to a limit on the neutrino mass of less than 0.06 eV. Similarly with 1000 kg of 116-CdWO_4 crystals located in the BOREXINO apparatus the neutrino mass limit can be pushed down to m_nu<0.02 eV.
Exploring the parent population of beamed NLS1s: from the black hole to the jet
M. Berton,L. Foschini,S. Ciroi,A. Caccianiga,V. Cracco,G. La Mura,F. Di Mille,M. L. Lister,S. Mathur,B. M. Peterson,J. L. Richards,E. Congiu,M. Frezzato,P. Rafanelli
Physics , 2015,
Abstract: The aim of this work is to understand the nature of the parent population of beamed narrow-line Seyfert 1 galaxies (NLS1s), by studying the physical properties of three parent candidates samples: steep-spectrum radio-loud NLS1s, radio-quiet NLS1s and disk-hosted radio-galaxies. In particular, we focused on the black hole mass and Eddington ratio distribution and on the interactions between the jet and the narrow-line region.
Implantología post-extracción inmediata: protocolo operativo y evaluaciones oclusales, periodontales y estéticas
Caccianiga,GL; Calzavara,D; Baldini,A; Baldoni,RM; Bascones,A;
Avances en Periodoncia e Implantología Oral , 2003, DOI: 10.4321/S1699-65852003000200003
Abstract: background: the purpose of this work is to evaluate the clinic efficiency of the surgical protocol in relation to the immediate placement of the screw into a post- extractive alveolus. materials and methods: according to albrekston and buser' s criterions, 45 implants which had been placed with the post-extractive technique were scored after 6 months and after 3 years since the placement of the dental implant. results: the applied protocol has proven to be suitable, the rate of success compared with the traditional technique has been similar, with the advantages of reducing notoriously the time to rehabilitate occ1usion and gaining aesthetics for the patient. conclusions: with this new surgical and implantologic protocol it can be guaranteed a high rate of success reducing the intervention phase while adding aesthetic, functional and occ1usal advantages.
Efecto bactericida del láser de diodo en periodoncia
Caccianiga,G.; Urso,E.; Monguzzi,R.; Gallo,K.; Rey,G.;
Avances en Odontoestomatología , 2008, DOI: 10.4321/S0213-12852008000200003
Abstract: laser in odontology, thanks to its antibacterial capabilities, haemostatic and of minor operating symptomatology, finds a vast field of application within the framework of periodontal therapy. in this study has been tested the effectiveness of a protocol that foresees the associated use of laser irradiation and hydrogen peroxide with the goal of reducing the bacterial charge of stocks commonly present in the active periodontal pockets and resistant to the bactericide action of laser irradiation alone such as prevotella intermedia, fusobacterium nucleatum, peptostreptococcus micron. the laboratory method used foresees the following protocol: each bacterial suspension has been exposed to hydrogen peroxide at 3% concentrations and it has been irradiated with laser for 10, 15 or 20 seconds, using sterile 1.5 ml eppendorf tubes. the results confirm the higher bactericide effectiveness of the combined action of hydrogen peroxide and laser. the microbiological cultivations carried out reveal how, in spite of the bactericide effect, the laser has an insufficient action on bacterial stocks tested if it isn?t associated with hydrogen peroxide. particularly in the case of the prevotella intermedia or the fusobacterium nucleatum the use of just hydrogen peroxide at 3% has offered better results than the laser irradiation alone while the association of both treatments has always offered optimal results. in the case of the peptostreptococcus micron the use of hydrogen peroxide and laser separately has offered an insufficient reduction of the bacterial count while the association of treatments has increased their bactericide action.
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