A5018595778- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Dark Matter and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Particle Detector Development and Performance
- Radio Astronomy Observations and Technology
- Spectroscopy and Chemometric Analyses
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- Particle physics theoretical and experimental studies
- Galaxies: Formation, Evolution, Phenomena
- Neutrino Physics Research
- Inertial Sensor and Navigation
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Statistical and numerical algorithms
- Advanced X-ray and CT Imaging
- Cosmology and Gravitation Theories
University of Rome Tor Vergata
2020-2025
National Institute for Astrophysics
2006-2024
Goddard Space Flight Center
2014-2023
Deleted Institution
2012-2023
Institute for Space Astrophysics and Planetology
2023
University of Maryland, College Park
2013-2022
Osservatorio Astronomico di Padova
2019
Friedrich-Alexander-Universität Erlangen-Nürnberg
2019
Max Planck Society
2018
University of California, Santa Cruz
2018
With the first direct detection of merging black holes in 2015, era gravitational wave (GW) astrophysics began. A complete picture compact object mergers, however, requires an electromagnetic (EM) counterpart. We report ultraviolet (UV) and X-ray observations by Swift Nuclear Spectroscopic Telescope ARray (NuSTAR) EM counterpart binary neutron star merger GW170817. The bright, rapidly fading emission indicates a high mass ($\approx0.03$ solar masses) wind-driven outflow with moderate...
We present our broadband study of GW170817 from radio to hard X-rays, including NuSTAR and Chandra observations up 165 days after the merger, a multi-messenger analysis LIGO constraints. The data are compared with predictions wide range models, providing first detailed comparison between non-trivial cocoon jet models. Homogeneous power-law shaped jets, as well simple models ruled out by data, while both Gaussian energy injection can describe current dataset for reasonable physical...
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...
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.
Wide-field optical surveys have begun to uncover large samples of fast (trise ≲ 5 d), luminous (Mpeak < −18), blue transients. While commonly attributed the breakout a supernova shock into dense wind, great distances transients this class found so far hampered detailed investigation their properties. We present photometry and spectroscopy from comprehensive worldwide campaign observe AT 2018cow (ATLAS 18qqn), first fast-luminous transient be in real time at low redshift. Our spectra (<2 days...
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts long (>2 s) duration produced by the core-collapse massive stars, those short (< 2 merger two neutron stars (NSs). A third class events with hybrid properties was identified, but never conclusively linked to a stellar progenitor. The lack bright supernovae rules out typical explosions, their distance scales prevent sensitive searches for direct signatures progenitor system. Only...
We present the results of our year-long afterglow monitoring GW170817, first binary neutron star (NS) merger detected by advanced LIGO and Virgo. New observations with Australian Telescope Compact Array (ATCA) Chandra X-ray were used to constrain its late-time behavior. The broadband emission, from radio X-rays, is well-described a simple power-law spectrum index ~0.585 at all epochs. After an initial shallow rise ~t^0.9, displayed smooth turn-over, reaching peak luminosity ~5e39 erg/s 160...
Long-duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars. Among them, GRB 221009A is by far brightest burst ever observed. Because its enormous energy (Eiso ≈ 1055 erg) and proximity (z 0.15), an exceptionally rare event that pushes limits our theories. We present multiwavelength observations covering first 3 months afterglow evolution. The x-ray brightness decays as a power law with slope ≈t-1.66, which not consistent standard predictions...
Abstract The Einstein Probe (EP) is an interdisciplinary mission of time-domain and X-ray astronomy. Equipped with a wide-field lobster-eye focusing imager, EP will discover cosmic transients monitor the variability known sources in 0.5–4 keV, at combination detecting sensitivity cadence that not accessible to previous current monitoring missions. can perform quick characterisation or outbursts Wolter-I telescope onboard. In this paper, science objectives are presented. expected enlarge...
Abstract The recent launch of Einstein Probe (EP) in early 2024 opened up a new window onto the transient X-ray sky, allowing for real-time discovery and follow-up fast transients (FXRTs). Multiwavelength observations FXRTs their counterparts are key to characterize properties outflows and, ultimately, identify progenitors. Here, we report our long-term radio monitoring EP 240315A, long-lasting (∼1000 s) high-redshift ( z = 4.9) FXRT associated gamma-ray burst (GRB) 240315C. Our campaign,...
We present the first systematic investigation of morphological and timing properties flares in GRBs observed by Swift XRT. consider a large sample drawn from all detected Swift, INTEGRAL, HETE-2 prior to 2006 January 31, which had an XRT follow-up showed significant flaring. Our 33 includes long short, at low high redshift, total 69 flares. The strongest occur early phases, with clear anticorrelation between flare peak intensity time occurrence. Fitting each X-ray Gaussian model, we find...
We present a detailed analysis of Swift multi-wavelength observations GRB 070110 and its remarkable afterglow. The early X-ray light curve, interpreted as the tail prompt emission, displays spectral evolution already seen in other gamma-ray bursts. optical afterglow shows shallow decay up to ~2 d after burst, which is not consistent with standard models. most intriguing feature very steep flux at ~20 ks ending an apparent plateau. abrupt drop curve rules out external shock origin plateau...
Abstract We present Hubble Space Telescope ( HST ) and Chandra imaging, combined with Very Large MUSE integral field spectroscopy of the counterpart host galaxy first binary neutron star merger detected via gravitational-wave emission by LIGO Virgo, GW170817. The galaxy, NGC 4993, is an S0 at z = 0.009783. There evidence for large, face-on spiral shells in continuum edge-on features visible nebular lines. This suggests that 4993 has undergone a relatively recent <mml:math...
Long duration gamma-ray bursts (GRBs) are thought to be produced by the core-collapse of a rapidly-rotating massive star. This event generates highly relativistic jet and prompt X-ray emission arises from internal shocks in or magnetised outflows. If stellar core does not immediately collapse black hole, it may form an unstable, millisecond pulsar, magnetar. As spins down, magnetar would inject energy into causing distinctive bump GRB light curve where becomes fairly constant followed steep...
Multimessenger observations of GW170817 have not conclusively established whether the merger remnant is a black hole (BH) or neutron star (NS). We show that long-lived magnetized NS with poloidal field B ≈ 1012 G fully consistent electromagnetic dataset, when spin-down losses are dominated by gravitational wave (GW) emission. The required ellipticity ε ≳ 10−5 can result from toroidal magnetic component much stronger than component, configuration expected an newly formed merger. Abrupt...
GRB 160821B is a short duration gamma-ray burst (GRB) detected and localized by the Neil Gehrels Swift Observatory in outskirts of spiral galaxy at z=0.1613, projected physical offset 16 kpc from galaxy's center. We present X-ray, optical/nIR radio observations its counterpart model them with two distinct components emission: standard afterglow, arising interaction relativistic jet surrounding medium, kilonova, powered radioactive decay sub-relativistic ejecta. Broadband modeling afterglow...
To date, the Burst Alert Telescope (BAT) onboard Swift has detected ~ 1000 gamma-ray bursts (GRBs), of which 360 GRBs have redshift measurements, ranging from z = 0.03 to 9.38. We present analyses BAT-detected for past 11 years up through GRB151027B. report summaries both temporal and spectral GRB characteristics using event data (i.e., each photon within approximately 250 s before 950 after BAT trigger time), discuss instrumental sensitivity selection effects detections. also explore...