A5048462485- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Mechanics and Biomechanics Studies
- CCD and CMOS Imaging Sensors
- High-pressure geophysics and materials
- Radiation Detection and Scintillator Technologies
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Nuclear Physics and Applications
- Galaxies: Formation, Evolution, Phenomena
- Calibration and Measurement Techniques
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Advanced X-ray and CT Imaging
- Cosmology and Gravitation Theories
- Particle accelerators and beam dynamics
- Stellar, planetary, and galactic studies
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
2015-2024
Istituto Nazionale di Fisica Nucleare
2015-2024
University of Pisa
2006-2024
Max Planck Society
2018
Monash University
2018
University of Geneva
2016
Tsinghua University
2016
Goddard Space Flight Center
2015
Turku Centre for Computer Science
2015
University of Turku
2015
The dwarf spheroidal satellite galaxies of the Milky Way are some most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack astrophysical backgrounds, widely considered be among promising targets for indirect detection via $\ensuremath{\gamma}$ rays. Here we report on $\ensuremath{\gamma}$-ray observations 25 based 4 years Fermi Large Area Telescope (LAT) data. None significantly detected in rays, present flux upper limits between 500 MeV GeV. We...
Dark matter particle annihilation or decay can produce monochromatic gamma-ray lines and contribute to the diffuse background. Flux upper limits are presented for spectral from 7 200 GeV background 4.8 264 obtained two years of Fermi Large Area Telescope data integrated over most sky. We give cross-section lifetime lower dark models that spectrum, including proposed as explanations PAMELA cosmic-ray data.
On 2015 June 16, Fermi-LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with peak $>100$ MeV flux of $\sim3.6\times10^{-5}\;{\rm photons}\;{\rm cm}^{-2}\;{\rm s}^{-1}$ averaged over orbital period intervals. It is historically highest $\gamma$-ray source including past EGRET observations, isotropic luminosity reaching $\sim10^{49}\;{\rm erg}\;{\rm s}^{-1}$. During outburst, Fermi spacecraft, which has an 95.4 min, was operated in special pointing mode to optimize...
Launched on 2021 December 9, the Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Small Mission in collaboration with Italian Space Agency (ASI). The mission will open new window of investigation—imaging x-ray polarimetry. observatory features three identical telescopes, each consisting mirror module assembly polarization-sensitive imaging detector at focus. A coilable boom, deployed orbit, provides necessary 4-m focal length. utilizes three-axis-stabilized spacecraft, which services such...
We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in γ-ray spectrum of NGC 1275, central galaxy Perseus cluster. Using 6 years Fermi Large Area Telescope data, we find no evidence ALPs exclude couplings above 5×10^{-12} GeV^{-1} ALP masses 0.5≲m_{a}≲5 neV at 95% confidence. The limits are competitive with sensitivity planned laboratory experiments, and, together other bounds, strongly constrain possibility that can...
The event selection developed for the Fermi Large Area Telescope before launch has been periodically updated to reflect constantly improving knowledge of detector and environment in which it operates. Pass 7, released public August 2011, represents most recent major iteration this incremental process. In parallel, LAT team undertaken a coherent long-term effort aimed at radical revision entire event-level analysis, based on experience gained prime phase mission. This includes virtually every...
We present a measurement of the cosmic-ray electron+positron spectrum between 7 GeV and 2 TeV performed with almost seven years data collected Fermi Large Area Telescope. find that is well fit by broken power law break energy at about 50 GeV. Above GeV, described single spectral index $3.07 \pm 0.02 \; (\text{stat+syst}) 0.04 (\text{energy measurement})$. An exponential cutoff lower than 1.8 excluded 95\% CL.
Abstract We present a search for spatial extension in high-latitude ( ) sources recent Fermi point source catalogs. The result is the High-Latitude Extended Sources Catalog, which provides extensions (or upper limits thereof) and likelihood profiles suite of tested morphologies. find 24 extended sources, 19 were not previously characterized as extended. These include that are potentially associated with supernova remnants star-forming regions. also found γ -ray emission vicinity Cen A radio...
XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to Astronomy. At time of writing XIPE in competitive phase A as fourth medium size ESA (M4). It promises reopen polarimetry window high energy Astrophysics after more than 4 decades thanks detector that efficiently exploits photoelectric effect and optics with large effective area. uniqueness time-spectrally-spatially- resolved breakthrough astrophysics fundamental physics. Indeed payload consists three Gas Pixel Detectors...
ixpeobssim is a simulation and analysis framework, based on the Python programming language associated scientific ecosystem, specifically developed for Imaging X-ray Polarimetry Explorer (IXPE). Given source model response functions of telescopes, it designed to produce realistic simulated observations, in form event lists FITS format, containing strict super-set information provided by standard IXPE level-2 files. The core capabilities are complemented full suite post-processing...
While X-ray Spectroscopy, Timing and Imaging have improved verymuch since 1962, when the first astronomical non-solar source was discovered, especially with launch of Newton/X-ray Multi-Mirror Mission, Rossi/X-ray Explorer Chandra/Advanced Astrophysics Facility, progress polarimetry has been meager. This is in part due to lack sensitive polarization detectors, fate approved missions because celestial sources appeared less polarized than expected. Only one positive measurement available until...
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto hole, which heats the sufficiently to emit x-rays. We report polarimetric observation of XRB Cygnus X-1 using Imaging Polarimetry Explorer. The electric field position angle aligns with outflowing jet, indicating that jet launched inner emitting region. polarization degree (4.01+-0.20)% at 2 8 kiloelectronvolts, implying accretion disk viewed closer edge-on than orbit. observations reveal...
Abstract Imaging X-ray Polarimetry Explorer (IXPE) is a Small mission by NASA and Agenzia Spaziale Italiana, launched on 2021 December 9, dedicated to investigating polarimetry allowing angular-, time-, energy-resolved observations in the 2–8 keV energy band. IXPE science observation phase since 2022 January; it comprised of three identical telescopes with grazing-incidence mirrors, each one having focal plane gas pixel detector. In this paper, we present possible guideline obtain an optimal...
ABSTRACT We present an X-ray spectropolarimetric analysis of the bright Seyfert galaxy NGC 4151. The source has been observed with Imaging Polarimetry Explorer (IXPE) for 700 ks, complemented simultaneous XMM–Newton (50 ks) and NuSTAR (100 pointings. A polarization degree Π = 4.9 ± 1.1 per cent angle Ψ 86° 7° east north (68 confidence level) are measured in 2–8 keV energy range. shows that could be entirely due to reflection. Given low reflection flux IXPE band, this requires, however, a...
GRB110721A was observed by the Fermi Gamma-ray Space Telescope using its two instruments Large Area (LAT) and Burst Monitor (GBM). The burst consisted of one major emission episode which lasted for ~24.5 seconds (in GBM) had a peak flux 5.7\pm0.2 x 10^{-5} erg/s/cm^2. time-resolved spectrum is best modeled with combination Band function blackbody spectrum. energy component initially 15\pm2 MeV, highest value ever detected in GRB. This measurement made possible combining GBM/BGO data LAT Low...
ABSTRACT We present results from γ -ray observations of the Coma cluster incorporating six years Fermi -LAT data and newly released “Pass 8” event-level analysis. Our analysis region reveals low-significance residual structures within virial radius that are too faint for a detailed investigation with current data. Using likelihood approach is free assumptions on spectral shape we derive upper limits flux expected energetic particle interactions in cluster. also consider benchmark spatial...
We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months Fermi Large Area Telescope (LAT) observations. An improved theoretical description cosmological DM signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predictions compared to previous work. More specifically, we estimate cosmologically-induced intensity have an uncertainty a...
Due to be launched in late 2021, the Imaging X-Ray Polarimetry Explorer (IXPE) is a NASA Small mission designed perform polarization measurements 2-8 keV band, complemented with imaging, spectroscopy and timing capabilities. At heart of focal plane set three polarization-sensitive Gas Pixel Detectors (GPD), each based on custom ASIC acting as charge-collecting anode. In this paper we shall review design, manufacturing, test IXPE focal-plane detectors, particular emphasis connection between...
An incremental version of the fourth catalog active galactic nuclei (AGNs) detected by Fermi-Large Area Telescope is presented. This (4LAC-DR3) derives from third data release 4FGL based on 12 years E>50 MeV gamma-ray data, where spectral parameters, energy distributions (SEDs), yearly light curves, and associations have been updated for all sources. The new reported AGNs include 587 blazar candidates four radio galaxies. We describe properties sample outline changes affecting previously...
IXPE is a Small Explorer mission that was launched at the end of 2021 to measure polarization X-ray emission from tens astronomical sources. Its focal plane detectors are based on Gas Pixel Detector, which measures by imaging photoelectron tracks in gas mixture and reconstructing their initial directions. The quality single track, then capability correctly determining original direction photoelectron, depends many factors, e.g., whether emitted low or high inclination with respect collection...
Abstract Particle acceleration mechanisms in supermassive black hole jets, such as shock acceleration, magnetic reconnection, and turbulence, are expected to have observable signatures the multiwavelength polarization properties of blazars. The recent launch Imaging X-Ray Polarimetry Explorer (IXPE) enables us, for first time, use X-ray band (2–8 keV) probe jet synchrotron emission high-synchrotron-peaked BL Lac objects (HSPs). We report discovery linear (degree Π x = 15% ± 2% electric...
Abstract We report the detection of X-ray polarization in neutron-star low-mass binary Scorpius (Sco) X-1 with PolarLight. The result is energy-dependent, a nondetection 3–4 keV but 4 σ 4–8 keV; it also flux-dependent band, when source displays low fluxes 5 during high fluxes, which case we obtain fraction 0.043 ± 0.008 and angle 52.°6 5.°4. This confirms previous marginal OSO-8 1970s marks Sco as second astrophysical significant measurement band. measured line jet orientation on sky plane...