X-Ray studies of the physics of matter around super-massive black-holes in nearby Seyfert galaxies

Seyfert galaxies are the closest active galactic nuclei. As such, we can use them to test the physical properties of the entire class of objects. To investigate their general properties, I took advantage of different methods of data analysis. In particular I used three different samples of objects, that, despite frequent overlaps, have been chosen to best tackle different topics: the heterogeneous BeppoS AX sample was thought to be optimized to test the average hard X-ray (E above 10 keV) properties of nearby Seyfert galaxies; the X-CfA was thought the be optimized to compare the properties of low-luminosity sources to the ones of higher luminosity and, thus, it was also used to test the emission mechanism models; finally, the XMM–Newton sample was extracted from the X-CfA sample so as to ensure a truly unbiased and well defined sample of objects to define the average properties of Seyfert galaxies. Taking advantage of the broad-band coverage of the BeppoS AX MECS and PDS instruments (between ~2-100 keV), I infer the average X-ray spectral propertiesof nearby Seyfert galaxies and in particular the photon index (~1.8), the high-energy cut-off (~290 keV), and the relative amount of cold reflection (~1.0). Moreover the unified scheme for active galactic nuclei was positively tested. The distribution of isotropic indicators used here (photon index, relative amount of reflection, high-energy cut-off and narrow FeK energy centroid) are similar in type I and type II objects while the absorbing column and the iron line equivalent width significantly differ between the two classes of sources with type II objects displaying larger absorbing columns. Taking advantage of the XMM–Newton and X–CfA samples I also deduced from measurements that 30 to 50% of type II Seyfert galaxies are Compton thick. Confirming previous results, the narrow FeK line is consistent, in Seyfert 2 galaxies, with being produced in the same matter responsible for the observed obscuration. These results support the basic picture of the unified model. Moreover, the presence of a X-ray Baldwin effect in type I sources has been measured using for the first time the 20-100 keV luminosity (EW proportional to L(20-100)^(−0.22±0.05)). This finding suggests that the torus covering factor may be a function of source luminosity, thereby suggesting a refinement of the baseline version of the unifed model itself. Using the BeppoSAX sample, it has been also recorded a possible correlation between the photon index and the amount of cold reflection in both type I and II sources. At a first glance this confirms the thermal Comptonization as the most likely origin of the high energy emission for the active galactic nuclei. This relation, in fact, naturally emerges supposing that the accretion disk penetrates, depending to the accretion rate, the central corona at different depths (Merloni et al. 2006): the higher accreting systems hosting disks down to the last stable orbit while the lower accreting systems hosting truncated disks. On the contrary, the study of the well defined X–C f A sample of Seyfert galaxies has proved that the intrinsic X-ray luminosity of nearby Seyfert galaxies can span values between 10^(38−43) erg s^−1, i.e. covering a huge range of accretion rates. The less efficient systems have been supposed to host ADAF systems without accretion disk. However, the study of the X–CfA sample has also proved the existence of correlations between optical emission lines and X-ray luminosity in the entire range of L_(X) covered by the sample. These relations are similar to the ones obtained if high-L objects are considered. Thus the emission mechanism must be similar in luminous and weak systems. A possible scenario to reconcile these somehow opposite indications is assuming that the ADAF and the two phase mechanism co-exist with different relative importance moving from low-to-high accretion systems (as suggested by the Gamma vs. R relation). The present data require that no abrupt transition between the two regimes is present. As mentioned above, the possible presence of an accretion disk has been tested using samples of nearby Seyfert galaxies. Here, to deeply investigate the flow patterns close to super-massive black-holes, three case study objects for which enough counts statistics is available have been analysed using deep X-ray observations taken with XMM–Newton. The obtained results have shown that the accretion flow can significantly differ between the objects when it is analyzed with the appropriate detail. For instance the accretion disk is well established down to the last stable orbit in a Kerr system for IRAS 13197-1627 where strong light bending effect have been measured. The accretion disk seems to be formed spiraling in the inner ~10-30 gravitational radii in NGC 3783 where time dependent and recursive modulation have been measured both in the continuum emission and in the broad emission line component. Finally, the accretion disk seems to be only weakly detectable in rk 509, with its weak broad emission line component. Finally, blueshifted resonant absorption lines have been detected in all three objects. This seems to demonstrate that, around super-massive black-holes, there is matter which is not confined in the accretion disk and moves along the line of sight with velocities as large as v~0.01-0.4c (whre c is the speed of light). Wether this matter forms winds or blobs is still matter of debate together with the assessment of the real statistical significance of the measured absorption lines. Nonetheless, if confirmed, these phenomena are of outstanding interest because they offer new potential probes for the dynamics of the innermost regions of accretion flows, to tackle the formation of ejecta/jets and to place constraints on the rate of kinetic energy injected by AGNs into the ISM and IGM. Future high energy missions (such as the planned Simbol-X and IXO) will likely allow an exciting step forward in our understanding of the flow dynamics around black holes and the formation of the highest velocity outflows.

Funzionalizzazione della mandibola dopo ricostruzione con lembo libero rivascolarizzato di fibula "single strut". Al di là del deficit di verticalità.

Obiettivi: Valutare la modalità  più efficace per la riabilitazione funzionale del limbo libero di fibula "single strut", dopo ampie resezioni per patologia neoplastica maligna del cavo orale. Metodi: Da una casistica di 62 ricostruzioni microvascolari con limbo libero di fibula, 11 casi sono stati selezionati per essere riabilitati mediante protesi dentale a supporto implantare. 6 casi sono stati trattati senza ulteriori procedure chirurgiche ad eccezione dell'implantologia (gruppo 1), affrontando il deficit di verticalità  della fibula attraverso la protesi dentaria, mentre i restanti casi sono stati trattati con la distrazione osteogenetica (DO) della fibula prima della riabilitazione protesica (gruppo 2). Il deficit di verticalità  fibula/mandibola è stato misurato. I criteri di valutazione utilizzati includono la misurazione clinica e radiografica del livello osseo e dei tessuti molli peri-implantari, ed il livello di soddisfazione del paziente attraverso un questionario appositamente redatto. Risultati: Tutte le riabilitazioni protesiche sono costituite da protesi dentali avvitate su impianti. L'età  media è di 52 anni, il rapporto uomini/donne è di 6/5. Il numero medio di impianti inseriti nelle fibule è di 5. Il periodo massimo di follow-up dopo il carico masticatorio è stato di 30 mesi per il gruppo 1 e di 38.5 mesi (17-81) di media per il gruppo 2. Non abbiamo riportato complicazioni chirurgiche. Nessun impianto è stato rimosso dai pazienti del gruppo 1, la perdita media di osso peri-implantare registrata è stata di 1,5 mm. Nel gruppo 2 sono stati riportati un caso di tipping linguale del vettore di distrazione durante la fase di consolidazione e un caso di frattura della corticale basale in assenza di formazione di nuovo osso. L'incremento medio di osso in verticalità è stato di 13,6 mm (12-15). 4 impianti su 32 (12.5%) sono andati persi dopo il periodo di follow-up. Il riassorbimento medio peri-implantare, è stato di 2,5 mm. Conclusioni: Le soluzioni più utilizzate per superare il deficit di verticalità  del limbo libero di fibula consistono nell'allestimento del lembo libero di cresta iliaca, nel posizionare la fibula in posizione ideale da un punto di vista protesico a discapito del profilo osseo basale, l'utilizzo del lembo di fibula nella versione descritta come "double barrel", nella distrazione osteogenetica della fibula. La nostra esperienza concerne il lembo libero di fibula che nella patologia neoplastica maligna utilizziamo nella versione "single strut", per mantenere disponibili tutte le potenzialità  di lunghezza del peduncolo vascolare, senza necessità  di innesti di vena. Entrambe le soluzioni, la protesi dentale ortopedica e la distrazione osteogenetica seguita da protesi, entrambe avvitate su impianti, costituiscono soluzioni soddisfacenti per la riabilitazione funzionale della fibula al di là  del suo deficit di verticalità . La prima soluzione ha preso spunto dall'osservazione dei buoni risultati della protesi dentale su impianti corti, avendo un paragonabile rapporto corona/radice, la DO applicata alla fibula, sebbene sia risultata una metodica con un numero di complicazioni più elevato ed un maggior livello di riassorbimento di osso peri-implantare, costituisce in ogni caso una valida opzione riabilitativa, specialmente in caso di notevole discrepanza mandibulo/fibulare. Decisiva è la scelta del percorso terapeutico dopo una accurata valutazione di ogni singolo caso. Vengono illustrati i criteri di selezione provenienti dalla nostra esperienza.

CAMINOS ANTIGUOS DEL NUEVO MUNDO Bolivia - Sudamérica, Siglos XIV - XVII, através de fuentes arqueológicas y etnohistóricas

La tesis "CAMINOS ANTIGUOS DEL NUEVO MUNDO Bolivia - Sudamerica, Siglos XV - XVII, através de fuentes arqueológicas y etnohistóricas", expone una compleja red vial en el territorio hoy conocido como Bolivia: corazón de Sudamérica (llamado así por su posición central en el subcontinente. Es el primer estudio arqueológico-histórico sobre el transporte en Bolivia, un vasto territorio, conocido por los Inkas (Siglo XIII) como Antisuyu y Collasuyu, una tierra desconocida, inexplorada, montañosa y selvática, poblada por diversas culturas, que habían desarrollado un sistema de tráfico fluvio-terrestre, que les permitiera recorrer tan extenso y contrastado territorio entre Andes y Amazonía. Los españoles le llamaban Alto Perú hacia el 1538, creando en 1559 la Real Audiencia de Charcas principal institución del Alto Perú, que pertenecía al Virreinato del Perú hasta 1776, año en el que se crea el Virreinato del Río de La Plata y el Alto Perú pasa a ser parte de este último. El Alto Perú se independiza de la Corona española en 1826, creándose la República de Bolivia. Sobre la base del primer mapa de Bolivia de 1859, en el que se hace un primer levantamiento de las redes camineras y la complementación con mapas más antiguos del Archivo General de Indias de Sevilla, se desarrolla el presente estudio, complementado con trabajos arqueológicos en la región e investigaciones en los Archivos Históricos de La Paz, Tarija, Santa Cruz y Buenos Aires que contienen manuscritos coloniales inéditos anexados en la presente tesis . El estudio es un aporte importante en el estableciemiento del Qapacñan o Caminos reales y sagrados de los Inkas, por cuanto Bolivia siendo un territorio central en Sudamérica fue un enclave cultural no solo en el periodo inka sino también pre inka. El estudio apunta a conocer la real dimensión del periodo prehistórico inka y pre inka en la región, en cuanto la mayoría de las vías actuales o  modernas, se encuentran sobre un trazado antiguo cuyos restos conservan aún la construcción formal de la ingenieria inka o pre inka. Las fuentes etnohistóricas que complementan la investigación corresponden principalmente a los siglos XV a XVII e información arqueológica concerniente al Periodo Inka (siglos XIV – XV aprox.).

Troposphere Calibration Techniques for Deep Space Probe Tracking

Ground-based Earth troposphere calibration systems play an important role in planetary exploration, especially to carry out radio science experiments aimed at the estimation of planetary gravity fields. In these experiments, the main observable is the spacecraft (S/C) range rate, measured from the Doppler shift of an electromagnetic wave transmitted from ground, received by the spacecraft and coherently retransmitted back to ground. If the solar corona and interplanetary plasma noise is already removed from Doppler data, the Earth troposphere remains one of the main error sources in tracking observables. Current Earth media calibration systems at NASA’s Deep Space Network (DSN) stations are based upon a combination of weather data and multidirectional, dual frequency GPS measurements acquired at each station complex. In order to support Cassini’s cruise radio science experiments, a new generation of media calibration systems were developed, driven by the need to achieve the goal of an end-to-end Allan deviation of the radio link in the order of 3×〖10〗^(-15) at 1000 s integration time. The future ESA’s Bepi Colombo mission to Mercury carries scientific instrumentation for radio science experiments (a Ka-band transponder and a three-axis accelerometer) which, in combination with the S/C telecommunication system (a X/X/Ka transponder) will provide the most advanced tracking system ever flown on an interplanetary probe. Current error budget for MORE (Mercury Orbiter Radioscience Experiment) allows the residual uncalibrated troposphere to contribute with a value of 8×〖10〗^(-15) to the two-way Allan deviation at 1000 s integration time. The current standard ESA/ESTRACK calibration system is based on a combination of surface meteorological measurements and mathematical algorithms, capable to reconstruct the Earth troposphere path delay, leaving an uncalibrated component of about 1-2% of the total delay. In order to satisfy the stringent MORE requirements, the short time-scale variations of the Earth troposphere water vapor content must be calibrated at ESA deep space antennas (DSA) with more precise and stable instruments (microwave radiometers). In parallel to this high performance instruments, ESA ground stations should be upgraded to media calibration systems at least capable to calibrate both troposphere path delay components (dry and wet) at sub-centimetre level, in order to reduce S/C navigation uncertainties. The natural choice is to provide a continuous troposphere calibration by processing GNSS data acquired at each complex by dual frequency receivers already installed for station location purposes. The work presented here outlines the troposphere calibration technique to support both Deep Space probe navigation and radio science experiments. After an introduction to deep space tracking techniques, observables and error sources, in Chapter 2 the troposphere path delay is widely investigated, reporting the estimation techniques and the state of the art of the ESA and NASA troposphere calibrations. Chapter 3 deals with an analysis of the status and the performances of the NASA Advanced Media Calibration (AMC) system referred to the Cassini data analysis. Chapter 4 describes the current release of a developed GNSS software (S/W) to estimate the troposphere calibration to be used for ESA S/C navigation purposes. During the development phase of the S/W a test campaign has been undertaken in order to evaluate the S/W performances. A description of the campaign and the main results are reported in Chapter 5. Chapter 6 presents a preliminary analysis of microwave radiometers to be used to support radio science experiments. The analysis has been carried out considering radiometric measurements of the ESA/ESTEC instruments installed in Cabauw (NL) and compared with the requirements of MORE. Finally, Chapter 7 summarizes the results obtained and defines some key technical aspects to be evaluated and taken into account for the development phase of future instrumentation.

Dynamics of the halo gas in disc galaxies

This Thesis studies the dynamics of hot and cold gas outside the plane in galaxies like the Milky-Way (extra-planar gas) and focuses on the interaction between disc and halo material. Stationary models for the cold phase of the extra-planar gas are presented. They show that the kinematics of this phase must be influenced by the interaction with an ambient medium that we identify as the hot cosmological corona that surrounds disc galaxies. To study this interaction a novel hydrodynamical code has been implemented and a series of hydrodynamical simulations has been run to investigate the mass and momentum exchange between the cold extra-planar gas clouds and the hot corona. These simulations show that the coronal gas can condense efficiently in the turbulent wakes that form behind the cold clouds and it can be accreted by the disc to sustain star formation. They also predict that the corona cannot be a static structure but it must rotate and lag by approximately 80-120 km/s with respect to the disc. Implications of the results of this Thesis for the evolution of star-forming galaxies and for the large-scale dynamics of galactic coronae are also briefly discussed.