G. L. Israel
A5051838727- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Astronomical Observations and Instrumentation
- SAS software applications and methods
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Mechanics and Biomechanics Studies
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Geophysics and Sensor Technology
- Particle Detector Development and Performance
- Astrophysics and Star Formation Studies
- Scientific Measurement and Uncertainty Evaluation
- Statistical and numerical algorithms
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Advanced X-ray Imaging Techniques
- Galaxies: Formation, Evolution, Phenomena
- Earthquake Detection and Analysis
Astronomical Observatory of Rome
2016-2025
National Institute for Astrophysics
2015-2025
University of Nova Gorica
2018
University of Southampton
2017
Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
2009-2017
Tsinghua University
2016
Instituto de Astrofísica de Andalucía
2016
Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
2016
Institute for Space Astrophysics and Planetology
2014
CEA Paris-Saclay
2005-2011
Spinning up an extragalactic neutron star Ultraluminous x-ray sources (ULXs) are strange objects in other galaxies that cannot be explained by conventional accretion onto stellar-mass objects. This has led to exotic interpretations, such as the long-sought intermediate-mass black holes. Israel et al. observed a ULX nearby galaxy NGC 5907 and found it is instead star. The spinning accreting material so fast its spin period quickly accelerating. only way can consume enough explain these...
One of the primary science goals next generation hard X-ray timing instruments is to determine equation state matter at supranuclear densities inside neutron stars, by measuring radius stars with different masses accuracies a few percent. Three main techniques can be used achieve this goal. The first involves waveform modelling. flux we observe from hotspot on star surface offset rotational pole will modulated star's rotation, giving rise pulsation. Information about mass and encoded into...
We have discovered rapid quasi-periodic oscillations (QPOs) in RXTE/PCA measurements of the pulsating tail 2004 December 27 giant flare SGR 1806-20. QPOs at ~92.5 Hz are detected a 50 s interval starting 170 after onset flare. These appear to be associated with increased emission by relatively hard unpulsed component and seen only over phases 7.56 spin period pulsations away from main peak. ~18 ~30 also ~200-300 This is first time that unambiguously flux soft gamma-ray repeater or any other...
We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to September 2009, for total 76 GRBs, and present an additional three pre-Swift not included in earlier sample. Furthermore, we publish 840 new points 42 GRB afterglows, sets 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A 080810. analyzed light curves all derived spectral energy distributions with best quality, allowing us estimate host...
NGC 7793 P13 is a variable (luminosity range ~100) ultraluminous X-ray source (ULX) proposed to host stellar-mass black hole of less than 15 M$_{\odot}$ in binary system with orbital period 64 d and 18-23 B9Ia companion. Within the EXTraS project we discovered pulsations at ~0.42 s two XMM-Newton observations P13, during which was detected $L_{\mathrm{X}}\sim2.1\times10^{39}$ $5\times10^{39}$ erg s$^{-1}$ (0.3-10 keV band). These findings unambiguously demonstrate that compact object neutron...
Soft gamma repeaters and anomalous x-ray pulsars form a rapidly increasing group of sources exhibiting sporadic emission short bursts. They are believed to be magnetars, i.e. neutron stars powered by extreme magnetic fields, B~10^{14}-10^{15} Gauss. We report on soft repeater with low field, SGR 0418+5729, recently detected after it emitted bursts similar those magnetars. X-ray observations show that its dipolar field cannot greater than 7.5x10^{12} Gauss, well in the range ordinary radio...
Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called "short/hard" "long/soft." The latter conclusively linked to explosive deaths massive stars, while former are thought result from merger or collapse compact objects. In recent years, indications accumulating that short/hard versus long/soft division does not map directly onto what would be expected classes progenitors, leading a new classification scheme Type I...
Abstract We discovered 2.8 s pulsations in the X-ray emission of ultraluminous source (ULX) M51 ULX-7 within UNSEeN project, which was designed to hunt for new pulsating ULXs (PULXs) with XMM-Newton. The pulse shape is sinusoidal, and large variations its amplitude were observed even single exposures (pulsed fraction from less than 5% 20%). Source variable, generally at an luminosity between 10 39 40 erg −1 , located outskirts spiral galaxy M51a a distance 8.6 Mpc. According our analysis,...
Ultraluminous X-ray sources (ULXs) with neutron star (NS) accretors pose a challenge to traditional accretion models, sparking debate regarding the role of geometrical beaming and strong magnetic fields (B). The reduction Thomson cross-section in presence B leads modification Eddington limit; therefore, it is expected affect significantly observational appearance NS-ULXs. We investigate this using population synthesis models explore its effects on luminosity functions, spin-up rates, outflow...
We report on the long term X-ray monitoring with Swift, RXTE, Suzaku, Chandra and XMM-Newton of outburst newly discovered magnetar Swift J1822.3-1606 (SGR 1822-1606), from first observations soon after detection short bursts which led to its discovery, through stages decay (covering time-span July 2011, until end April 2012). also archival ROSAT witnessed source during likely quiescent state, upper limits J1822.3-1606's radio-pulsed optical emission outburst, Green Bank Telescope (GBT) Gran...
We report on the discovery of a new member magnetar class, SGR J1935+2154, and its timing spectral properties measured by an extensive observational campaign carried out between 2014 July 2015 March with Chandra XMM–Newton (11 pointings). discovered spin period J1935+2154 through detection coherent pulsations at about 3.24 s. The is slowing down rate |$\dot{P} = 1.43(1)\times 10^{-11}$| s s−1 decreasing trend due to negative |$\ddot{P}$| −3.5(7) × 10−19 s−2. This implies surface dipolar...
eXTP is a science mission designed to study the state of matter under extreme conditions density, gravity and magnetism. Primary goals are determination equation at supra-nuclear measurement QED effects in highly magnetized star, accretion strong-field regime gravity. targets include isolated binary neutron stars, strong magnetic field systems like magnetars, stellar-mass supermassive black holes. The carries unique unprecedented suite state-of-the-art scientific instruments enabling for...
The center of our Galaxy hosts a supermassive black hole, Sagittarius (Sgr) A*. Young, massive stars within 0.5 pc Sgr A* are evidence an episode intense star formation near the hole few million years ago, which might have left behind young neutron traveling deep into A*'s gravitational potential. On 2013 April 25, short X-ray burst was observed from direction Galactic center. With series observations with Chandra and Swift satellites, we pinpoint associated magnetar at angular distance 2.4...
Ultraluminous X-ray sources (ULXs) are a population of extragalactic objects whose luminosity exceeds the Eddington limit for 10 Msun black hole (BH). Their properties have been widely interpreted in terms accreting stellar-mass or intermediate-mass BHs. However at least three neutron stars (NSs) recently identified ULXs through discovery periodic pulsations. Motivated by these findings we studied spectral sample bright using simple continuum model which was extensively used to fit spectra...
ABSTRACT The 6.67 hr periodicity and the variable X-ray flux of central compact object (CCO) at center supernova remnant RCW 103, named 1E 161348–5055, have been always difficult to interpret within standard scenarios an isolated neutron star (NS) or a binary system. On 2016 June 22, Burst Alert Telescope (BAT) on board Swift detected magnetar-like short burst from direction also coincident with large long-term outburst. Here, we report Chandra , Nuclear Spectroscopic Array (BAT XRT)...
There is growing evidence that two classes of high-energy sources, the soft gamma repeaters and anomalous X-ray pulsars, contain slowly spinning "magnetars," i.e., neutron stars whose emission powered by release energy from their extremely strong magnetic fields (>1015 G). We show here enormous liberated in 2004 December 27 giant flare SGR 1806-20 (~5 × 1046 ergs), together with likely recurrence time such events, requires an internal field strength ≳1016 G. Toroidal this are within order...
Optical spectroscopic identification of the nature 21 unidentified southern hard X-ray objects is reported here in framework our campaign aimed at determining newly-discovered and/or sources detected by INTEGRAL. Our results show that 5 these are magnetic Cataclysmic Variables (CVs), 4 High-Mass Binaries (HMXBs; one which Large Magellanic Cloud) and 12 Active Galactic Nuclei (AGNs). When feasible, main physical parameters for also computed using multiwavelength information available...