A5016889508- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- SAS software applications and methods
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- High-pressure geophysics and materials
- Mechanics and Biomechanics Studies
- Astronomy and Astrophysical Research
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Particle physics theoretical and experimental studies
- Ionosphere and magnetosphere dynamics
- GNSS positioning and interference
- Atomic and Subatomic Physics Research
- Geophysics and Sensor Technology
- Earthquake Detection and Analysis
- Stellar, planetary, and galactic studies
Osservatorio Astronomico di Cagliari
2016-2025
Institute for Space Astrophysics and Planetology
2010-2024
National Institute for Astrophysics
2009-2024
Observatoire astronomique de Strasbourg
2024
Centre National de la Recherche Scientifique
2024
Istituto Nazionale di Fisica Nucleare
2021-2023
Massachusetts Institute of Technology
2022-2023
Astronomical Observatory of Rome
2023
University of Insubria
2009-2022
Marshall Space Flight Center
2021-2022
The International Pulsar Timing Array project combines observations of pulsars from both northern and southern hemisphere observatories with the main aim detecting ultra-low frequency (∼ 10−9–10−8 Hz) gravitational waves. Here we introduce project, review methods used to search for waves emitted coalescing supermassive binary black-hole systems in centres merging galaxies discuss status project.
Very high energy (VHE) γ-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35, z = 0.432) was detected with MAGIC Cherenkov telescopes during a short observation (∼0.5 hr) performed on 2010 June 17. The detection coincides high-energy MeV/GeV activity measured by Large Area Telescope (LAT) board Fermi satellite. VHE extends about 70 GeV up to at least 400 and can be well described power-law dN/dE ∝ E−Γ photon index Γ 3.75 ± 0.27stat 0.2syst. averaged integral flux...
The well known Crab Nebula is at the center of SN1054 supernova remnant. It consists a rotationally-powered pulsar interacting with surrounding nebula through relativistic particle wind. emissions originating from and have been considered to be essentially stable. Here we report detection strong gamma-ray (100 MeV-10 GeV) flares observed by AGILE satellite in September, 2010 October, 2007. In both cases, unpulsed flux increased factor 3 compared non-flaring flux. flare luminosity short...
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 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...
Abstract We report on an observational campaign the bright black hole (BH) X-ray binary Swift J1727.8–1613 centered around five observations by Imaging Polarimetry Explorer. These track for first time evolution of polarization a BH across hard to soft state transition. The 2–8 keV degree decreased from ∼4% ∼3% observations, but angle remained oriented in north–south direction throughout. Based with Australia Telescope Compact Array, we find that intrinsic 7.25 GHz radio aligns polarization....
We report the detection by Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite of terrestrial gamma ray flashes (TGFs) obtained with minicalorimeter (MCAL) detector operating in energy range 0.3–100 MeV. select events typically lasting few milliseconds spectral and directional selections consistent TGF characteristics previously reported other space missions. During period 1 June 2008 to 31 March 2009 we detect 34 high‐confidence showing millisecond durations geographical distribution...
Strong electric discharges associated with thunderstorms can produce terrestrial gamma-ray flashes (TGFs), i.e., intense bursts of x rays and $\ensuremath{\gamma}$ lasting a few milliseconds or less. We present in this Letter new TGF timing spectral data based on the observations Italian Space Agency AGILE satellite. determine that emission above 10 MeV has significant power-law component reaching energies up to 100 MeV. These results challenge theoretical models runaway electron...
Faraday rotation measurements using the current and next generation of low-frequency radio telescopes will provide a powerful probe astronomical magnetic fields. However, achieving full potential these requires accurate removal time-variable ionospheric contribution. We present ionFR, code that calculates amount for specific epoch, geographic location, line-of-sight. ionFR uses number publicly available, GPS-derived total electron content maps most recent release International Geomagnetic...
Pulsars emit low-frequency radio waves through to high-energy gamma-rays that are generated anywhere from the surface out edges of magnetosphere. Detecting correlated mode changes in multi-wavelength emission is therefore key understanding physical relationship between these sites. Through simultaneous observations, we have detected synchronous switching and X-ray properties PSR B0943+10. When pulsar a sustained 'bright' mode, X-rays show only an un-pulsed, non-thermal component. Conversely,...
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...
We report the detection of 48 millisecond pulsars (MSPs) out 75 observed thus far using LOFAR in frequency range 110-188 MHz. have also detected three MSPs nine 38-77 This is largest sample ever at these low frequencies, and half were for first time frequencies below 200 present average pulse profiles MSPs, their effective widths, flux densities compare with higher observing frequencies. The flux-calibrated, multifrequency are publicly available via EPN Database Pulsar Profiles. values...
We determined Faraday rotation measures (RMs) towards 137 pulsars in the northern sky, using Low-Frequency Array (LOFAR) observations at 110-190 MHz. This low-frequency RM catalogue, largest to date, improves precision of existing measurements on average by a factor 20 - due low frequency and wide bandwidth data, aided synthesis method. report RMs 25 for first time. The were corrected ionospheric increase accuracy our catalogue approximately 0.1 rad m$^{\rm -2}$. correction is currently...
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...
Very long baseline interferometric (VLBI) localisations of repeating fast radio bursts (FRBs) have demonstrated a diversity local environments: from nearby star-forming regions to globular clusters. Here we report the VLBI localisation FRB 20201124A using an ad-hoc array dishes that also participate in European Network (EVN). In our campaign, detected 18 total at two separate epochs. By combining visibilities both observing epochs, were able localise with 1-$\sigma$ error 4.5 milliarcseconds...
We report on the first detection of linearly polarized x-ray emission from an ultra-magnetized neutron star with Imaging X-ray Polarimetry Explorer (IXPE). The IXPE 35 observations anomalous pulsar 4U 0142+61 reveal a linear polarization degree $(12\pm 1)\%$ throughout 2--8 keV band. detect substantial variation energy: is $(14\pm at 2--4 and $(41\pm 7)\%$ 5.5--8 keV, while it drops below instrumental sensitivity around 4--5 where angle swings by $\sim 90^\circ$. give us completely new...
Abstract We report the first detection of X-ray polarization bright transient Swift J1727.8−1613 with Imaging Polarimetry Explorer. The observation was performed at beginning 2023 discovery outburst, when source resided in hard state. find a time- and energy-averaged degree 4.1% ± 0.2% angle 2.°2 1.°3 (errors 68% confidence level; this translates to ∼20 σ significance detection). This finding suggests that hot corona emitting bulk detected X-rays is elongated, rather than spherical....
Abstract We present the IXPE observation of GRB 221009A, which includes upper limits on linear polarization degree both prompt and afterglow emission in soft X-ray energy band. 221009A is an exceptionally bright gamma-ray burst (GRB) that reached Earth 2022 October 9 after traveling through dust Milky Way. The Imaging Polarimetry Explorer (IXPE) pointed at 11 to observe, for first time, 2–8 keV a afterglow. set limit 13.8% 99% confidence level. This result provides constraints jet opening...
Abstract The lower-energy peak of the spectral energy distribution blazars has commonly been ascribed to synchrotron radiation from relativistic particles in jets. Despite consensus regarding jet emission processes, particle acceleration mechanism is still debated. Here, we present first X-ray polarization observations PG 1553+113, a high-synchrotron-peak blazar observed by Imaging Polarimetry Explorer (IXPE). We detect an degree (10 ± 2)% along electric-vector position angle ψ X = 86° 8°....
ABSTRACT We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy IC 4329A. The Imaging Polarimetry Explorer (IXPE) observed source for ∼500 ks, supported by XMM–Newton (∼60 ks) and NuSTAR (∼80 exposures. detect polarization in 2–8 keV band with 2.97σ confidence. report a degree 3.3 ± 1.1 per cent angle 78° 10° (errors are 1σ confidence). is consistent being aligned radio jet, albeit partially due to large uncertainties on position angle. jointly fit spectra from three...