M. Del Santo
A5106497253- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Particle Detector Development and Performance
- Mechanics and Biomechanics Studies
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Adaptive optics and wavefront sensing
- Dark Matter and Cosmic Phenomena
- Radiation Detection and Scintillator Technologies
- Particle Accelerators and Free-Electron Lasers
- Stellar, planetary, and galactic studies
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Neutrino Physics Research
- Calibration and Measurement Techniques
- Medical Imaging Techniques and Applications
- Scientific Measurement and Uncertainty Evaluation
- Nuclear physics research studies
- Solar and Space Plasma Dynamics
- History and Developments in Astronomy
- Advanced X-ray Imaging Techniques
- Relativity and Gravitational Theory
National Institute for Astrophysics
2015-2024
Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo
2015-2024
Space (Italy)
2024
North-West University
2022
University of Palermo
2021
University of Cagliari
2020-2021
Institute for Space Astrophysics and Planetology
2012-2020
Politecnico di Milano
2020
University of Oxford
2019
Michigan State University
2010-2016
Abstract We present the first X-ray polarization measurements of GX 339–4. IXPE observed this source twice during its 2023–2024 outburst, once in soft-intermediate state and again a soft state. The observation taken intermediate shows significant (4 σ ) degree P X = 1.3% ± 0.3% angle θ −74° 7° only 3–8 keV band. FORS2 at Very Large Telescope simultaneously, detecting optical B , V R I bands (between ∼0.1% ∼0.7%), all roughly aligned with polarization. also detect discrete jet knot from radio...
A low-mass planet around a white dwarf Numerous exoplanets have been detected Sun-like stars. These stars end their lives as dwarfs, which should inherit any surviving planetary systems. Manser et al. found periodic shifts in emission lines from disc of gas orbiting (see the Perspective by Fossati). They used numerical simulations to show that most likely explanation for spectral is within disc. The must be unusually small and dense avoid being ripped apart tidal forces. authors speculate it...
The ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) Project led by the Italian National Institute for Astrophysics (INAF) is developing and will deploy at Observatorio del Teide mini-array (ASTRI Mini-Array) composed of nine telescopes similar to small-size dual-mirror Schwarzschild-Couder telescope (ASTRI-Horn) currently operating on slopes Mt. Etna in Sicily. Mini-Array surpass current Cherenkov array differential sensitivity above few tera-electronvolt (TeV), extending...
Abstract The Imaging X-ray Polarimetry Explorer measured with high significance the polarization of brightest Z-source, Sco X-1, resulting in nominal 2–8 keV energy band a degree 1.0% ± 0.2% and angle 8° 6° at 90% confidence level. This observation was strictly simultaneous observations performed by NICER, NuSTAR, Insight-HXMT, which allowed for precise characterization its broadband spectrum from soft to hard X-rays. source has been observed mainly state, short periods flaring. We also...
We report the first high-energy survey catalog obtained with IBIS gamma-ray imager on board INTEGRAL. The analysis has been performed first-year Core Program ISGRI data comprising both Galactic Plane Scan and Centre Deep Exposure pointings for a total exposure time exceeding 5 Ms. This initial revealed presence of ~120 sources detected unprecedented sensitivity ~1 mcrab in energy range 20-100 keV. Each source is located to an accuracy between 1' 3', depending its brightness. outstanding...
Most ULXs are believed to be powered by super-Eddington accreting neutron stars and, perhaps, black holes. Above the Eddington rate disc is expected thicken and launch powerful winds through radiation pressure. Winds have been recently discovered in several ULXs. However, it yet unclear whether thickening of or wind variability causes switch between classical soft supersoft states observed some In order understand such phenomenology overall mechanism, we undertook a large (800 ks) observing...
Abstract This paper reports the first detection of polarization in X-rays for atoll-source 4U 1820−303, obtained with Imaging X-ray Polarimetry Explorer (IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements were also performed radio Australia Telescope Compact Array. The IXPE observations 1820−303 coordinated Swift Telescope, Neutron Star Interior Composition Explorer, and Nuclear Spectroscopic Array aiming to obtain an accurate spectral model covering a broad...
We aim to investigate the energy-resolved pulse profile changes of accreting X-ray pulsar focusing in cyclotron line energy range, using full set available observations. applied a tailored pipeline study dependence profiles and build pulsed fraction spectra (PFS) for different also studied cross-correlation lag spectra. re-analysed search links between local features observed PFS spectral emission components associated with shape fundamental line. In data, sufficiently high statistics, we...
The imager on board INTEGRAL (IBIS) presently provides the most detailed sky images ever obtained at energies above 30 keV. telescope is based a coded aperture imaging system which allows to obtain in large field of view 29deg x with an angular resolution 12'. System Point Spread Function and its characteristics are here described along specific analysis algorithms used derive accurate point-like source locations. derived location accuracy studied using first in-flight calibration data...
On 2004 August 15, we observed a fast (shorter than 10 h) state transition in the bright black hole transient GX 339–4 simultaneously with Rossi X-Ray Timing Explorer (RXTE) and INTEGRAL. This was evident both timing spectral properties. Combining data from Proportional Counter Array (PCA), High-Energy X-ray Experiment (HEXTE) Imager on Board INTEGRAL Satellite (IBIS), obtained good quality broad-band (3–200 keV) energy spectra before after transition. These indicate that hard component...
We report on the first detection of very high-energy (VHE) gamma-ray emission from Crab Nebula by a Cherenkov telescope in dual-mirror Schwarzschild-Couder (SC) configuration. The result has been achieved means 4 m size ASTRI-Horn telescope, operated Mt. Etna (Italy) and developed context Telescope Array Observatory preparatory phase. SC design is aplanatic characterized small plate scale, allowing us to implement large field view cameras with small-size pixel sensors high compactness....
The Galactic black hole transient GRS1915+105 is famous for its markedly variable X-ray and radio behaviour, being the archetypal galactic source of relativistic jets. It entered an outburst in 1992 has been active ever since. Since 2018 declined into extended low-flux plateau, occasionally interrupted by multi-wavelength flares. Here we report properties collected this new phase, compare recent data to historic observations. We find that while emission remained unprecedentedly low most time...
Ultraluminous X-ray sources (ULX) are extragalactic objects with luminosities above the Eddington limit for a 10 Msun black hole (BH). ULXs may host super-Eddington accreting neutron stars or stellar mass BH, although exact proportion of two populations is not yet known. We investigate properties ULX NGC 4559 X7, which shows flux variability up to factor 5 on months-to-years and hours-to-days timescales. A flaring activity was also observed during source highest epochs. Flares unpredictable,...
Context. Ultraluminous X-ray sources (ULX) are extragalactic objects with observed luminosities largely above the Eddington limit for a 10 M ⊙ black hole. Currently, it is believed that ULXs host super-Eddington accreting neutron stars or stellar mass holes. However, exact proportion of two populations compact not yet known. Aims. We investigate properties ULX NGC 4559 X7 (hereafter X7), which shows flux variability up to factor five on both long (months years) and short (hours days)...
We report on a campaign of X-ray and soft gamma-ray observations the black hole candidate H 1743-322 (also named IGR J17464-3213), performed with RXTE, INTEGRAL Swift satellites. The source was observed during short outburst between 2008 October 03 November 16. evolution hardness-intensity diagram throughout is peculiar, in that it does not follow canonical pattern through all spectral states (the so called q-track pattern) seen black-hole transients. On contrary, only makes transition from...
The different electron distributions in the hard and soft spectral states (HS SS) of BH binaries could be caused by kinetic processes changing because varying physical conditions corona. In presence a magnetic field corona, distribution can appear thermal, even when acceleration mechanisms would produce non thermal distributions. This is due to fast efficient thermalization through synchrotron self-absorption. We have analyzed data from 6 years observations Cygnus X-1 with INTEGRAL...
The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final down-selection for a launch slot 2022-2024. Thanks to unprecedented combination of effective area spectral resolution its main instrument, LOFT will study behaviour matter under extreme conditions, such as strong gravitational field innermost regions accretion flows close black holes neutron stars, supra-nuclear densities interior stars. science payload is based on...
On 2011 August 11, INTEGRAL discovered the hard X-ray source IGR J17361-4441 near centre of globular cluster NGC 6388. Follow up observations with Chandra showed position transient was inconsistent dynamical centre, and thus not related to its possible intermediate mass black hole. The a peculiar spectrum (Gamma \approx 0.8) no evidence QPOs, pulsations, type-I bursts, or radio emission. Based on peak luminosity, classified as very faint transient, most likely low-mass binary. We re-analysed...
We report on the coordinated observations of neutron star low-mass X-ray binary (NS-LMXB) GX 5−1 in X-rays (IXPE, NICER, NuSTAR , and INTEGRAL), optical (REM LCO), near-infrared (REM), mid-infrared (VLT VISIR), radio (ATCA). This Z-source was observed by IXPE twice March–April 2023 (Obs. 1 2). In band source detected, but only upper limits to linear polarization were obtained at a 3 σ level 6.1% 5.5 GHz 5.9% 9 Obs. 12.5% 20% 2. The mid-IR, near-IR, suggest presence compact jet that peaks...
The X-ray transient XMMU J174716.1–281048 was serendipitously discovered with XMM-Newton in 2003. It lies about 0.9 degrees off the Galactic Centre and its spectrum shows a high absorption (~ cm-2). Previous observations of source field performed 2000 2001 did not detect source, indicative quiescent emission at least two orders magnitude fainter. low luminosity during outburst (~34 erg s-1 8 kpc) indicates that is member “very faint transients” class. On 2005 March 22nd INTEGRAL satellite...