A5017027631- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Mechanical Behavior of Composites
- Structural Health Monitoring Techniques
- Composite Structure Analysis and Optimization
- Adaptive optics and wavefront sensing
- Advanced Statistical Methods and Models
- Ultrasonics and Acoustic Wave Propagation
- Structural Analysis and Optimization
- Probabilistic and Robust Engineering Design
- Scientific Measurement and Uncertainty Evaluation
- Turbomachinery Performance and Optimization
- Hydraulic and Pneumatic Systems
- Control Systems and Identification
- Calibration and Measurement Techniques
- Structural Response to Dynamic Loads
- Thermography and Photoacoustic Techniques
- History and Developments in Astronomy
- Aerospace and Aviation Technology
University of Turin
2023
University of Ferrara
2021
Michigan State University
2015
Politecnico di Milano
2011-2014
University of Bologna
1994-2013
Osservatorio astronomico di Bologna
2009-2013
National Institute for Astrophysics
2011
Center for Astrophysics Harvard & Smithsonian
2003-2009
Harvard University
2004-2009
Constituency for Africa
2005
We present multiple Chandra and XMM-Newton observations of the type 1.8 Seyfert Galaxy NGC 1365, which shows most dramatic X-ray spectral changes observed so far in an AGN: source switched from reflection dominated to transmission back just 6 weeks. During this time soft thermal component, arising a ~1 kpc region around center, remained constant. The component is constant at all timescales, its high flux relative primary implies presence thick gas covering large fraction solid angle. gas,...
We present an occultation of the central X-ray-emitting region in Seyfert galaxy NGC 1365. This extreme spectral variation (from Compton-thin to reflection-dominated and back 4 days) has been caught a 10 day Chandra monitoring campaign consisting six short (15 ks) observations performed every 2 days. discuss implications this within scenario Compton-thick cloud crossing line sight X-ray source. estimate source size R ≤ 1014 cm distance from D 1016 cm. direct measurement confirms theoretical...
We present results from the photometric and spectroscopic identification of 122 X-ray sources recently discovered by XMM-Newton in 2-10 keV band (the HELLAS2XMM 1dF sample). Their flux cover range 8E-15-4E-13 cgs total area surveyed is 0.9 deg2. About 20% hard selected have an to optical ratio (X/O) ten times or more higher than that optically AGN. Unlike faint found ultra-deep Chandra surveys, which reach (and optical) fluxes one order magnitude lower survey sources, many extreme X/O our...
We present a complete analysis of the hard X-ray (2-10 keV) properties Seyfert galaxy NGC 1365, based on 60 ks XMM-Newton observation performed in January 2004. The two main results are: 1) detect an obscuring cloud with N_H~3.5x10^23 cm^(-2) crossing line sight ~25 ks. This implies dimension source not larger than few 10^13 cm and distance order 10^16 cm. Adopting black hole mass M(BH) estimated from M(BH)-velocity dispersion relation, size is D_S<20 R_G density clouds are R~3000-10000...
Recent X-ray surveys have clearly demonstrated that a population of optically dull, X-ray-bright galaxies is emerging at 2-10 keV fluxes the order 10-14 ergs cm-2 s-1. Although they might constitute an important fraction sources responsible for hard background, their nature still unknown. With aim better understanding physical mechanisms observed properties, we started extensive program multiwavelength follow-up observations X-ray, quiet discovered with XMM-Newton. Here report results what...
We present the first results from an XMM-Newton serendipitous medium-deep survey, which covers nearly 3 deg2. detect a total of 1022, 495, and 100 sources, down to minimum fluxes about 5.9 × 10-16, 2.8 10-15, 6.2 10-15 ergs cm-2 s-1, in 0.5-2, 2-10, 4.5-10 keV bands, respectively. In soft band this is one largest samples available date surely 2-10 at our limiting X-ray flux. The measured log N- S determinations are found be good agreement with previous determinations. 0.5-2 band, we break...
Abstract We present an analysis of the extreme obscuration variability observed during XMM–Newton 5-d continuous monitoring active galactic nuclei (AGN) in NGC 1365. The source was a reflection-dominated state first ∼1.5 d, then strong increase 7—10 keV emission ∼10 h, followed by symmetric decrease. spectral different states clearly shows that this variation is due to uncovering X-ray source. From observation, we estimate size DS &lt; 1013 cm, distance obscuring clouds R∼ 1016 cm and...
We present the discovery of four absorption lines in X-ray spectrum Seyfert galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The are detected with high statistical confidence (from >20 σ for strongest to ~4 weakest) two XMM-Newton observations 60 ks long. also detect same lines, a lower signal-to-noise ratio (but still >2 each line), previous shorter (~10 ks) observations. spectral analysis identifies these features as Fe XXV XXVI Kα Kβ outflowing velocities varying ~1000 ~5000 km s-1...
The spectroscopic analysis of 117 serendipitous sources in the HELLAS2XMM 1df (1 degree field) survey is described. Of these, 106 sources, which 86% have a redshift, are used to evaluate fraction X-ray absorbed (log ) Active Galactic Nuclei (AGN) 2-10 keV flux range erg cm-2 s-1. This turns out lower than what predicted by two well known Cosmic X-Ray Background synthesis models, and discrepancy significant at 99.999% level. result consolidates findings recently obtained other authors. In...
We present the analysis of temperature and metallicity profiles 12 galaxy clusters in redshift range 0.1--0.3 selected from Chandra archive with at least ~20,000 net ACIS counts kT>6 keV. divide sample between 7 Cooling-Core (CC) 5 Non-Cooling-Core (NCC) according to their central cooling time. find that single power-laws can describe properly both radii larger than 0.1 r_180 CC NCC systems, showing objects steeper outwards. A significant deviation is only inner r_180. perform a...
We present Chandra ACIS-I and ACIS-S observations (~200ks in total) of the X-ray luminous elliptical galaxy NGC4636, located outskirts Virgo cluster. A soft band (0.5-2 keV) image shows presence a bright core center surrounded by an extended corona two pronounced quasi-symmetric, 8 kpc long, arm-like features. Each this features defines rim ellipsoidal bubble. An additional bubble-like feature, whose northern is ~2 south north-eastern arm, detected as well. surface brightness temperature...
We present the combined analysis of metal content 83 objects in redshift range 0.09-1.39, and spatially-resolved 3 bins (0-0.15, 0.15-0.4, >0.4) R500, as obtained with similar using XMM-Newton data Leccardi & Molendi (2008) Baldi et al. (2012). use pseudo-entropy ratio to separate Cool-Core (CC) cluster population, where central gas density tends be relatively higher, cooler more rich, from Non-Cool-Core systems. The average, redshift-independent, abundance measured radial decrease...
Our X-ray study of the nuclear activity in a new sample six quiescent early-type galaxies, and larger from literature, confirmed (Soria et al., Paper I) that Bondi accretion rate diffuse hot gas is not good indicator supermassive black hole (SMBH) luminosity. Here we suggest more reliable estimate must include released by stellar population inside sphere influence SMBH, addition to inflow across surface. We use optical surface-brightness profiles mass-loss stars region: show for our galaxies...
We have studied the nuclear activity in a sample of six quiescent early-type galaxies, with new Chandra data and archival HST optical images. Their sources X-ray luminosities ~1038-1039 ergs s-1 (LX/LEdd ~ 10-8 to 10-7) colors or spectra consistent accreting supermassive black holes (SMBHs), except for nucleus NGC 4486B, which is softer than typical AGN spectra. In few cases, morphology shows hints marginally extended structures, addition surrounding diffuse thermal emission from hot gas,...
Context. We present an XMM-Newton analysis of the X-ray spectra 39 clusters galaxies at 0.4 < z 1.4, covering a temperature range 1.5 ≲ kT 11 keV.
We present extensive optical, radio and infrared follow-up observations of a sample 35 hard X–ray (2–10 keV) selected sources discovered serendipitously in the PV XMM–Newton observation radio–loud quasar PKS 0312–77 field, for which also an archival Chandra is available. The have been carried out as part HELLAS2XMM survey, program aimed to understand nature responsible bulk Background (XRB). identification optical counterparts greatly benefits from positional accuracy obtained observations....
We present the integrated 411 ks Chandra ACIS-S exposure of Antennae galaxies (NGC 4038/39). Besides a rich population pointlike sources, this spectacular image reveals spatially and spectrally complex hot diffuse gaseous component. For first time we detect intense line emission from Fe, Ne, Mg, Si in obtain detailed picture varied metal abundances interstellar medium (ISM) galaxy. In certain regions, α-elements may be many times solar, while Fe abundance is subsolar or near-solar. The...
We present the properties of discrete X-ray sources detected in our monitoring survey Antennae galaxies with Chandra ACIS-S. detect ~70 down to a typical luminosity 7 × 1037 ergs s-1 each six observations. In co-added observation (which has total exposure 411 ks) we 120 s-1, depending on local background. Fifteen have strong extended component. Fourteen pointlike luminosities above 1039 at least one exposure, which qualifies them as ultraluminous (ULXs). Ten ULXs show long-term variability,...