L. Foschini
A5050633081- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Particle Detector Development and Performance
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Particle Accelerators and Free-Electron Lasers
- Neutrino Physics Research
- Planetary Science and Exploration
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Gyrotron and Vacuum Electronics Research
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- History and Developments in Astronomy
- High-pressure geophysics and materials
National Institute for Astrophysics
2012-2024
Brera Astronomical Observatory
2015-2024
University of Padua
2018
Guangzhou University
2018
Istituto Nazionale di Fisica Nucleare
2018
Istituto Nazionale di Fisica Nucleare, Sezione di Padova
2018
University of Turku
2007-2018
Aalto University
2018
Osservatorio Astronomico di Padova
2018
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
2016
We studied all blazars of known redshift detected by the Fermi satellite during its first 3-month survey. For majority them, pointed Swift observations ensure a good multiwavelength coverage, enabling us to reliably construct their spectral energy distributions (SEDs). model SEDs using one-zone leptonic and study derived interesting physical parameters as function observed γ-ray luminosity. confirm previous findings concerning relation with source luminosity which are at origin blazar...
The first three months of sky-survey operation with the Fermi Gamma Ray Space Telescope (Fermi) Large Area (LAT) reveals 132 bright sources at |b|>10 deg test statistic greater than 100 (corresponding to about 10 sigma). Two methods, based on CGRaBS, CRATES and BZCat catalogs, indicate high-confidence associations 106 these known AGNs. This sample is referred as LAT Bright AGN Sample (LBAS). It contains two radio galaxies, namely Centaurus A NGC 1275, 104 blazars consisting 57 flat...
We report the discovery with Fermi/LAT of gamma-ray emission from three radio-loud narrow-line Seyfert 1 galaxies: PKS 1502+036 (z=0.409), 1H 0323+342 (z=0.061) and 2004-447 (z=0.24). In addition to PMN J0948+0022 (z=0.585), first source this type be detected in gamma rays, they may form an emerging new class active galactic nuclei (AGN). These findings can have strong implications on our knowledge about relativistic jets unified model AGN.
The gamma-ray astronomical observatory INTEGRAL, succesfully launched on 17th October 2002, carries two large telescopes. One of them is the coded-mask imaging telescope onboard INTEGRAL satellite (IBIS) which provides high-resolution (≈12') sky images in energy range from 15 keV to 10 MeV with typical on-axis sensitivity ≈1 mCrab at 100 (3σ, 106 s exposure). We report here general description IBIS system and standard science data analysis procedures. These procedures reconstruct, clean...
We study the BL Lac objects detected in one year all sky survey of Fermi satellite, with a energy spectral slope alpha_gamma [0.1-100 GeV] band greater than 1.2. In vs gamma-ray luminosity plane, these Lacs occupy region populated by Flat Spectrum Radio Quasars (FSRQs). Studying properties their distributions (SED) and emitting lines, we find that several have SED similar to FSRQs they do broad lines large equivalent width, should be reclassified as even adopting current phenomenological...
We report the detection of high-energy gamma-ray emission from two starburst galaxies using data obtained with Large Area Telescope on board Fermi Gamma-ray Space Telescope. Steady point-like above 200 MeV has been detected at significance levels 6.8 sigma and 4.8 respectively, sources positionally coincident locations M82 NGC 253. The total fluxes are consistent originating interaction cosmic rays local interstellar gas radiation fields constitute evidence for a link between massive star...
Abstract TeV photons from blazars at relatively large distances, interacting with the optical–infrared cosmic background, are efficiently converted into electron–positron pairs. The produced pairs extremely relativistic (Lorentz factors of order 106– 107) and promptly lose their energy through inverse Compton scatterings microwave producing emission in GeV band. spectrum flux level this reprocessed critically dependent on intensity intergalactic magnetic field, B, that can deflect diluting...
We report the discovery by Large Area Telescope (LAT) onboard Fermi Gamma-ray Space of high-energy gamma-ray emission from peculiar quasar PMN J0948+0022 (z=0.5846). The optical spectrum this object exhibits rather narrow Hbeta (FWHM(Hbeta) ~ 1500 km s^-1), weak forbidden lines and is therefore classified as a narrow-line type I quasar. This class objects thought to have relatively small black hole mass accrete at high Eddington ratio. radio loudness variability compact core indicates...
We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources this type and omitting those with steep spectra. analyse data from frequencies to X-rays, supplement these information available online catalogues literature in order cover full electromagnetic spectrum. This is largest for source. detected 90% X-rays found 17% at γ rays. Extreme variability high energies was also found, down timescales as...
This is the first report of Fermi Gamma-Ray Space Telescope observations quasar 3C 454.3, which has been undergoing pronounced long-term outbursts since 2000. The data from Large Area Telescope, covering 2008 July 7–October 6, indicate strong, highly variable γ-ray emission with an average flux ∼3 × 10−6 photons cm−2 s−1, for energies >100 MeV. variable, distinct, symmetrically shaped flares increases by a factor several on timescale about 3 days. variability indicates compact region, and...
We reconsider the emission properties of BL Lac objects emitting in high-energy gamma-ray band exploiting new information MeV-GeV obtained by Large Area Telescope (LAT) onboard Fermi Gamma-Ray Space its first three months operation. To this aim we construct spectral energy distribution all Lacs revealed LAT and known TeV not detected LAT, also including data from Swift satellite, model them with a simple one-zone leptonic model. The analysis shows that (being or already band) share similar...
We study the four BL Lac objects (RGB J0152+017, 1ES 0229+200, 0347−121 and PKS 0548−322) detected in TeV band but not present first Fermi-LAT (1FGL) catalogue of Fermi/Large Area Telescope (LAT). analyse 24 months LAT data deriving γ-ray fluxes or upper limits that we use to assemble their spectral energy distributions (SED). model SEDs with a standard one-zone leptonic model, also including contribution reprocessed radiation multi-GeV band, emitted by pairs produced through conversion...
We report on observations of TeV-selected AGN made during the first 5.5 months with Large Area Telescope (LAT) on-board Fermi Gamma-ray Space (Fermi). In total, 96 were selected for study, each being either (i) a source detected at TeV energies (28 sources) or (ii) an object that has been studied instruments and which upper-limit reported (68 objects). The show clear detections 38 these objects, 21 are joint GeV-TeV sources 29 not in third EGRET catalog. For Fermi-detected sources, spectra...
We investigate the physical properties of 10 blazars at redshift greater than 2 detected in 3-years all sky survey performed by Burst Alert Telescope (BAT) onboard Swift satellite. find that jets these are among most powerful known. Furthermore, mass their central black hole, inferred from optical-UV bump, exceeds a few billions solar masses, with accretion luminosities being large fraction Eddington one. compare those brightest 3-months Large Area (LAT) Fermi BAT have more jets, luminous...
In the first week of December 2009, blazar 3C 454.3 became brightest high energy source in sky. Its photon flux reached and surpassed level 1e-5 ph/cm2/s above 100 MeV. The Swift satellite observed several times during period gamma-ray flux, we can construct really simultaneous spectral distributions (SED) before, during, after luminosity peak. Our main findings are: i) optical, X-ray fluxes correlate; ii) varies quadratically (or even more) with optical flux; iii) a simple one-zone...
We report about the search for short-term variability in high-energy gamma-ray energy band of three flat-spectrum radio quasars (3C 454.3, 3C 273, PKS B1222+216), whose flux at E > 100 MeV exceeded value 10^-5 ph cm^-2 s^-1 least one day. Although, statistics was not yet sufficient to effectively measure characteristic time scale, it allowed us set tight upper limits on observed doubling scale (< 2-3 hours) -- smallest measured date energies --, which can constrain size emitting region. The...
The flat spectrum radio quasar PKS 1222+216 was detected in the very high energy gamma-ray band by MAGIC during a highly active phase following an alert LAT onboard Fermi. Its relatively hard without cut off, together with observed variability on timescale of ~10 min challenges standard emission models. If originates portion relativistic jet located inside BLR, severe absorption gamma rays above few tens GeV is expected due to pair production process. These observations imply existence...
We revisited the spectroscopic characteristics of narrow-line Seyfert 1 galaxies (NLS1s) by analysing a homogeneous sample 296 NLS1s at redshift between 0.028 and 0.345, extracted from Sloan Digital Sky Survey (SDSS-DR7) public archive. confirm that are mostly characterized Balmer lines with Lorentzian profiles, lower black hole masses higher Eddington ratios than classic broad-line (BLS1s), but they also appear to be active galactic nuclei (AGNs) contiguous BLS1s sharing them common...
Flat-spectrum radio-loud Narrow-Line Seyfert 1 galaxies (NLS1s) are a recently discovered class of $\gamma$-ray emitting Active Galactic Nuclei (AGN), that exhibit some blazar-like properties which explained with the presence relativistic jet viewed at small angles. When blazars observed larger angles they appear as radio-galaxies, and we expect to observe an analogue parent population for beamed NLS1s. However, number known NLS1s large is not enough. Therefore, tried understand origin this...
We studied the radio emission from four radio-loud and gamma-ray-loud narrow-line Seyfert 1 galaxies. The goal was to investigate whether a relativistic jet is operating at source, quantify its characteristics. relied on most systematic monitoring of such system in cm mm bands which conducted with Effelsberg 100 m IRAM 30 telescopes covers longest time-baselines frequencies date. extract variability parameters compute brightness temperatures Doppler factors. powers were computed light curves...
We investigate the mid-infrared (mid-IR) properties of largest (42 objects) sample radio-loud narrow-line Seyfert 1 (RL NLS1) collected to date, using data from Wide-field Infrared Survey Explorer. analyse mid-IR colours these objects and compare them what is expected different combinations AGN galaxy templates. find that, in general, host emission gives an important contribution observed flux particular at longest wavelengths (W3, 12 μm, W4, 22 μm). In about half sources (22 objects), we...
Narrow-line Seyfert 1 galaxies (NLS1s) are an interesting subclass of active galactic nuclei (AGN), which tipically does not exhibit any strong radio emission.Seven percent them, though, radio-loud and often show a flat radio-spectrum (F-NLS1s).This, along to the detection γ-ray emission coming from is usually interpreted as sign relativistic beamed jet oriented line sight.An important aspect these AGN that must be understood nature their parent population, in other words how do they appear...