Studying the X-ray/UV Variability of Active Galactic Nuclei with data from Swift and XMM archives

Many efforts have been made in understanding the underlying origin of variability in Active Galactic Nuclei (AGN), but at present they could give still no conclusive answers. Since a deeper knowledge of variability will enable to understand better the accretion process onto supermassive black holes, here we present preliminary results of the first ensemble structure function analysis of the X-ray variability of samples of quasars with data from Swift and XMM-Newton archives. Moreover, it is known that UV and X-ray luminosities of quasars are correlated and recent studies quantified this relation across 5 orders of magnitude. In this context, we present here some preliminary results on the X-ray/UV ratio from simultaneous observations in UV and X-ray bands of a sample of quasars with data from XMM-Newton archive

Extragalactic jets in the SKA era: solving the mystery of Ultra High Energy Cosmic Rays?

The extreme properties shown by supermassive black holes at the centres of galaxies (active galactic nuclei; AGN) make them obvious candidates for producing Ultra High Energy Cosmic Rays (UHECRs), the most energetic particles known in the Universe. AGN can exhibit outflows in the form of powerful, collimated jets of particles, accelerated in some cases close to the speed of light. Although AGN jets dimension and magnetic field could in principle accelerate particles to extreme energies, it is not easy to develop a model which describes an efficient acceleration mechanism. Different solutions have been proposed, but they need further investigation from both observational and theoretical point of view: in fact, two pieces of astrophysical understanding would need revision, namely the parameters (size and magnetic fields) in jets of AGN, and the strength of the magnetic field in the local region of the Universe. The capabilities offered by the Square Kilometre Array (SKA) in improving current measures of the jet physical parameters will permit a better characterization of the magnetic field strength ,and its structure within the jet itself. This will be crucial to refine our estimations for the key parameters of the nearby γ-ray AGN, which are to date the best candidate sources of UHECRs

Probiotics Reduce Inflammation in Antiretroviral Treated, HIV-Infected Individuals: Results of the "Probio-HIV" Clinical Trial

BACKGROUND: HIV infection results in damage to the gastrointestinal (GI) tract, microbial translocation and immune activation. These are not completely normalized with combined antiretroviral therapy (cART). Moreover, increate morbidity and mortality of cART-treated HIV-infected individuals is associated with inflammation. METHODS: In order to enhance GI tract immunity, we recruited and treated 20 HIV-infected humans with cART supplemented with probiotics and followed inflammation and immunological parameters (clinical trial number NCT02164344). 11 HIV seronegative subjects were included as control group. The enumeration of CD4+, CD8+, CD38+ and HLA-DR+ lymphocytes were evaluated on peripheral blood; HIV-RNA levels, sCD14, d-dimer, C-reactive protein (CRP) high sensitivity C-reactive protein (hsCRP), IL-6 and Lipopolysaccharide Binding Protein (LBP) were assayed on plasma. RESULTS: We observe that cART does not normalize the levels of immune activation in HIV positive patients anyway inflammation and markers of microbial translocation were significantly reduced with probiotic supplementation. Patients show a clear and statistically significant reduction in the levels of immune activation on CD4 T-lymphocytes, for both markers CD38 and HLA-DR and their simultaneous expression, LBP and hsCRP plasma levels after probiotic diet supplementation settling to values comparable to controls. CONCLUSIONS: Supplementing cART with probiotics in HIV-infected individuals may improve GI tract immunity and there by mitigate inflammatory sequelae, ultimately improving prognosis

Motor and Linguistic Linking of Space and Time in the Cerebellum

Background: Recent literature documented the presence of spatial-temporal interactions in the human brain. The aim of the present study was to verify whether representation of past and future is also mapped onto spatial representations and whether the cerebellum may be a neural substrate for linking space and time in the linguistic domain. We asked whether processing of the tense of a verb is influenced by the space where response takes place and by the semantics of the verb. Principal Findings: Responses to past tense were facilitated in the left space while responses to future tense were facilitated in the right space. Repetitive transcranial magnetic stimulation (rTMS) of the right cerebellum selectively slowed down responses to future tense of action verbs; rTMS of both cerebellar hemispheres decreased accuracy of responses to past tense in the left space and to future tense in the right space for non-verbs, and to future tense in the right space for state verbs. Conclusions: The results suggest that representation of past and future is mapped onto spatial formats and that motor action could represent the link between spatial and temporal dimensions. Right cerebellar, left motor brain networks could be part of the prospective brain, whose primary function is to use past experiences to anticipate future events. Bot

External quality assessment of HIV-1 DNA quantification assays used in the clinical setting in Italy

none18no: Total cell-associated HIV-1 DNA is a surrogate marker of the HIV-1 reservoir, however, certified systems for its quantification are not available. The Italian HIV DNA Network was launched to validate HIV-1 DNA quantification methods in use at University and Hospital labs. A quality control panel including HIV-1 DNA standards, reconstructed blood samples (RBSs) and DNA from different HIV-1 subtypes was blindly tested by 12 participating labs by quantitative real-time PCR (n = 6), droplet digital PCR (n = 3) or both (n = 3). The median 95% hit rate was 4.6 (3.7-5.5) copies per test and linearity in the tested range was excellent (R2 = 1.000 [1.000-1.000]). The median values obtained across labs were 3,370 (2,287-4,245), 445 (299-498), 59 (40-81) and 7 (6-11) HIV-1 DNA copies, for the 3,584, 448, 56 and 7-copy standards, respectively. With RBSs, measured values were within twofold with respect to the median in two thirds of cases. HIV-1 subtypes were missed (CRF01_AE by 3 labs) or underestimated by > 1 log (subtypes A, C, D, F by one lab; CRF01_AE by one lab; CRF02_AG by one lab). The overall performance was excellent with HIV-1 DNA standards, however detection of different HIV-1 subtypes must be improved.openVicenti, Ilaria; Dragoni, Filippo; Giannini, Alessia; Casabianca, Anna; Lombardi, Francesca; Di Sante, Laura; Turriziani, Ombretta; Racca, Sara; Paolucci, Stefania; Lai, Alessia; Bon, Isabella; Abbate, Isabella; Rozera, Gabriella; Belmonti, Simone; Scutari, Rossana; Alteri, Claudia; Saladini, Francesco; Zazzi, MaurizioVicenti, Ilaria; Dragoni, Filippo; Giannini, Alessia; Casabianca, Anna; Lombardi, Francesca; Di Sante, Laura; Turriziani, Ombretta; Racca, Sara; Paolucci, Stefania; Lai, Alessia; Bon, Isabella; Abbate, Isabella; Rozera, Gabriella; Belmonti, Simone; Scutari, Rossana; Alteri, Claudia; Saladini, Francesco; Zazzi, Maurizi

Open Universe for Blazars: A new generation of astronomical products based on 14 years of Swift -XRT data

Aims. Open Universe for Blazars is a set of high-transparency multi-frequency data products for blazar science, and the tools designed to generate them. Blazars are drawing growing interest following the consolidation of their position as the most abundant type of source in the extragalactic very high-energy γ-ray sky, and because of their status as prime candidate sources in the nascent field of multi-messenger astrophysics. As such, blazar astrophysics is becoming increasingly data driven, depending on the integration and combined analysis of large quantities of data from the entire span of observational astrophysics techniques. The project was therefore chosen as one of the pilot activities within the United Nations Open Universe Initiative, whose objective is to stimulate a large increase in the accessibility and ease of utilisation of space science data for the worldwide benefit of scientific research, education, capacity building, and citizen science. Methods. Our aim is to deliver innovative data science tools for multi-messenger astrophysics. In this work we report on a data analysis pipeline called Swift-DeepSky based on the Swift XRTDAS software and the XIMAGE package, encapsulated into a Docker container. Swift-DeepSky downloads and reads low-level data, generates higher level products, detects X-ray sources, and estimates several intensity and spectral parameters for each detection, thus facilitating the generation of complete and up-to-date science-ready catalogues from an entire space-mission data set. Results. As a first application of our innovative approach, we present the results of a detailed X-ray image analysis based on Swift-DeepSky that was run on all Swift-XRT observations including a known blazar, carried out during the first 14 years of operations of the Neil Gehrels Swift Observatory. Short exposures executed within one week of each other have been added to increase sensitivity, which ranges between ∼1 × 10-12 and ∼1 × 10-14 erg cm-2 s-1 (0.3-10.0 keV). After cleaning for problematic fields, the resulting database includes over 27 000 images integrated in different X-ray bands, and a catalogue, called 1OUSXB, that provides intensity and spectral information for 33 396 X-ray sources, 8896 of which are single or multiple detections of 2308 distinct blazars. All the results can be accessed online in a variety of ways, from the Open Universe portal through Virtual Observatory services, via the VOU-Blazar tool and the SSDC SED builder. One of the most innovative aspects of this work is that the results can be easily reproduced and extended by anyone using the Docker version of the Swift-DeepSky pipeline, which runs on Linux, Mac, and Windows machines, and does not require any specific experience in X-ray data analysis.Fil: Giommi, Paolo. Università di Roma; Italia. International Center For Relativistic Astrophysics; Italia. Universitat Technical Zu Munich; AlemaniaFil: Brandt, C. H.. International Center For Relativistic Astrophysics; Italia. Jacobs University; AlemaniaFil: Barres de Almeida, U.. International Center For Relativistic Astrophysics; Italia. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Pollock, A. M. T.. University of Sheffield; Reino UnidoFil: Arneodo, F.. New York University Abu Dhabi; Arabia SauditaFil: Chang, Y. L.. International Center For Relativistic Astrophysics; ItaliaFil: Civitarese, Enrique Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: de Angelis, Maria Cruz. Università di Roma; ItaliaFil: D'Elia, V.. Space Science Data Center; Italia. Osservatorio Astronomico di Roma; ItaliaFil: Del Rio Vera, J.. United Nations Office for Outer Space Affairs; AustraliaFil: Di Pippo, S.. United Nations Office for Outer Space Affairs; AustraliaFil: Middei, Riccardo. Università di Roma; ItaliaFil: Penacchioni, Ana Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Perri, M.. Osservatorio Astronomico di Roma; Italia. Space Science Data Center; ItaliaFil: Ruffini, Remo. International Center For Relativistic Astrophysics; ItaliaFil: Sahakyan, Narek. International Centre For Relativistic Astrophysics Network; ArmeniaFil: Turriziani, Sara. Computational Astrophysics Laboratory; Japó

Studying the spectral shape and the X-ray/UV: variability of active galactic nuclei with data from swift and XMM archives

I Nuclei Galattici Attivi (AGN) hanno variazioni di flusso in tutte le bande dello spettro elettromagnetico. In effetti, la variabilità è stata una delle prime proprietà dei quasar ad essere riconosciuta. Sebbene la variabilità giochi un ruolo fondamentale nel dare una stima della grandezza del nucleo centrale degli AGN, la sua origine fisica rimane tuttora sconosciuta. Per spiegare le osservazioni ottiche spno stati proposti diversi meccanismi, ad esempio esplosioni di supernove, cattura di stelle, microlenti gravitazionali o instabilità del disco. La variabilità rapida nella banda X è dunque una delle caratteristiche di tutti gli AGN. Il breve tempo scala (103-105 s) delle variazioni di flusso X fornisce evidenza che l'emissione provenga da una regione compatta intorno al buco nero centrale supermassivo. Gli studi teorici (Shakura & Sunyaev 1973) riescono a spiegare l'emissione ottica ed ultravioletta come proveniente da un disco di accrescimento stabile e otticamente spesso, ma non sono in grado di fornire una spiegazione sull'origine dell'emissione mella banda X. È inoltre noto che le luminosità X e ultavioletta (UV) dei quasar sono tra loro correlate e studi recenti hanno accertato questa dipendenza su cinque ordine di grandezza (e.g. Strateva et al. 2005; Gibson et al. 2008) . Queste analisi cercano di comprendere la struttura e la fisica delle regioni nucleari dei quasar, ponendo dei vincoli sui modelli di connessione fisica tra le emissioni nella banda X ed in quella UV. Dal momento che si ritiene che i fotoni UV provengano dal disco di accrescimento, mentre i raggi X sono supposti essere originati in una corona che circonda il disco, lo studio del rapporto UV/X dà informazioni sull'equilibrio tra i dischi di accrescimento e le loro corone. In questo contesto, la mia tesi presenta alcuni risultati sulla relazione tra luminosità X e UV da osservazioni simultanee nelle bande X ed UV per un campione di quasar con dati estratti dall'archivio del satellite XMM-Newton (see Vagnetti et al. 2010a, for details). Alcune indicazioni sulla natura della variabilità possono essere ottenuti dall'analisi dello spettro di potenza, o della funzione di struttura, di curve di luce in singola banda. A parte lo studio delle curve di luce individuali, le proprietà d'insieme di campioni statistici di quasar (QSO) possono fornire ulteriori vincoli sull'origine della variabilità. Nelle bande ottiche l'analisi d'insieme di grandi campioni ottici (25000 sorgenti) è stata resa possibile dalla Sloan Digital Sky Survey (SDSS) ed ha permesso di caratterizzare la dipendenza della variabilità ottica con la luminosità, il redshift, la lunghezza d'onda e il ritardo temporale (Vanden Berk et al. 2004; de Vries et al. 2005). Un'analisi analoga non è stata ancora effettuata nella banda X ed ora diventa possibile grazie al campo di vista relativamente grande tipico della strumentazione X, quale quella a bordo dei satelliti XMM-Newton e Swift, che permette di recuperare dati dai campi di osservazioni individuali. Attualmente due database sono disponibili per questo tipo di studi, ovvero il Secondo Catalogo Serendipito di XMM (Watson et al. 2009) e il Catalogo Serendipito dei Campi Profondi centrati sui GRB osservati da Swift (Puccetti et al. 2010). Il primo è limitato, dai vincoli dell'orbita del satellite, a dati per variazioni su lunghi tempi scala (diversi mesi) e soffre di un campionamento temporale piuttosto rado. Al contrario il catalogo del satellite Swift fornisce un campionamento su tempi scala intermedi (da ore ad pochi mesi) per un numero di sorgenti sufficiente a calcolare una Funzione di Struttura d'insieme. Costruire una Funzione di Struttura d'insieme per gli AGN richiede di accertare la natura delle sorgenti serendipite X, in modo da escludere eventuali stelle e galassie normali che emettono in banda X, e conoscere il redshift delle sorgenti in modo da poter raggruppare tutte le variazioni di flusso individuali da in intervalli di ritardo temporale nel sistema di riferimento di quiete. Questa tesi presenta le prime Funzioni di Struttura della variabilità X per due campioni di quasar con spettri ottici dalla SDSS-DR7: ho utilizzato dati d'archivio dai cataloghi serendipiti dei satelliti Swift e XMM per ottenere una curva di crescita della variabilità X con l'intervallo temporale. L'esponente di scala della parte della Funzione di Struttura descrivibile a legge di potenza contiene importanti informazioni sul meccanismo di variabilità e potrebbe in principio essere usato per porre vincoli sui modelli di emisioni o sulle proprietà fisiche degli AGN. In questa tesi, segnalo che ho trovato Funzioni di Struttura regolari, ovvero esse non mostrano alcuna piega da poter mettere in relazione con la massa del buco nero MBH o la luminosità bolometrica Lbol o entrambe le grandezze. Infine, questa tesi presenta i risultati preliminari della campagnia di indetificazione ottica di acune sorgenti serendipite del satellite Swift condotta al TNG e sulle sorgenti radio serendipite con dati dalla SDSS-DR7 (Abazajian et al. 2009) scoperti nei campi profondi del satellite Swift.Active Galactic Nuclei (AGNs) show flux variations over the entire electromagnetic spectrum. Indeed, variability was one of the first recognized properties of quasars. Although variability plays a key role in constraining the size of the central engine of AGNs, its physical origin remains substantially unknown. Many mechanisms have been proposed to explain optical observations, such as supernova explosions, star capture, gravitational microlensing or disc instabilities. Rapid X-ray variability is indeed a hallmark of AGNs. X-ray short time scale (103-105 s) variability provides evidence that the emission comes from a compact region around the central supermassive black hole. Whereas theoretical studies (Shakura & Sunyaev 1973) provide an explanation of the optical-UV radiation from a steady, optically thick, accretion disc, they cannot explain the X-ray emission. Moreover, it is known that UV and X-ray luminosities of quasars are correlated and recent studies quantified this relation across 5 orders of magnitude (e.g. Strateva et al. 2005; Gibson et al. 2008) . Such studies inform ongoing efforts to understand the structure and the physics of quasars nuclear regions, providing constraints on models of physical associations between UV and X-ray emissions. Because UV photons are generally thought to be radiated from the accretion disc whereas X-rays are produced in the disc corona, the UV/X-ray luminosity relation is an indication of the balance between accretion discs and their coronae. In this context, I present in this thesis some results on the X-ray/UV relation from simultaneous observations in UV and X-ray bands of a sample of quasars with data from XMM-Newton archive (see Vagnetti et al. 2010a, for details). Some indication on the nature of variability can be obtained from the analysis of the power spectrum, or the structure function, of single-band lightcurves. Besides the study of individual lightcurves, ensemble properties of statistical quasar (QSO) samples can provide further constrains on the origin of variability. In the optical bands the ensemble analysis on large optical samples (25,000 objects) was made possible by the Sloan Digital Sky Survey (SDSS), and provided a characterization of the dependence of optical variability on luminosity, redshift, wavelength and time delay (Vanden Berk et al. 2004; de Vries et al. 2005). A similar analysis has not yet been performed in the X-ray, and now becomes possible thanks to the relatively wide field-of-view of typical X-ray instrumentation, such as those on-board XMM-Newton and Swift satellites, to retrieve field data from individual pointed observations. Two available databases are suitable for this analysis, i.e. the Second XMM-Newton serendipitous source catalogue (Watson et al. 2009), and the Swift Serendipitous Survey in deep XRT GRB fields (Puccetti et al. 2010). The former is limited, by orbital constraints, to long timescale (several months) variations and suffers for rather sparse sampling. On the contrary the Swift catalog provides a sampling at intermediate timescales (hours to a few months) for a number of objects sufficient to calculate an ensemble SF. To build an ensemble SF of the AGNs, it is necessary to ascertain the AGN nature of the X-ray serendipitous sources, excluding possible X-ray emitting stars or galaxies, and to know the redshifts of the sources in order to group all the individual flux variations of different objects in bins of rest-frame time lag. This thesis presents the first ensemble Structure Functions (SFs) of the X-ray variability of two samples of quasars with SDSS-DR7 optical spectra: I used archival data from the Swift and XMM serendipitous source catalogs to obtain a curve of growth of X-ray variability with time lag. The index of the power law portion of the SF contains important information on the variability mechanism and could in principle be used to put constraints on emission models or AGNs physical properties. Here, I report that I found smooth SFs, i.e. they do not show any bend to be related with the black hole mass MBH or the bolometric luminosity Lbol or both. Moreover, I present here results regarding the TNG optical identification campaign of some Swift serendipitous sources and the preliminary results on the serendipitous radio sources with SDSS-DR7 data (Abazajian et al. 2009) detected in Swift GRB deep fields