A5040201636- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Particle Accelerators and Free-Electron Lasers
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Particle Detector Development and Performance
- Neutrino Physics Research
- Astronomical Observations and Instrumentation
- Laser-Plasma Interactions and Diagnostics
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Astro and Planetary Science
- Mechanics and Biomechanics Studies
- Astrophysics and Star Formation Studies
- Scientific Research and Discoveries
- SAS software applications and methods
- Advanced X-ray Imaging Techniques
- Particle accelerators and beam dynamics
- Advanced X-ray and CT Imaging
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Power Line Communications and Noise
Istituto di Radioastronomia di Bologna
2018-2024
University of Bologna
2005-2023
Osservatorio astronomico di Bologna
2007-2023
National Institute for Astrophysics
2005-2023
Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
2021
Istituto Nazionale di Fisica Nucleare, Sezione di Bari
2021
University of Trieste
2021
Fermi National Accelerator Laboratory
2021
Astrophysique, Instrumentation et Modélisation
2016-2018
Institut de Recherche sur les Lois Fondamentales de l'Univers
2016-2018
The fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Gamma-ray Space Telescope Large Area (4LAC) between 2008 August 4 and 2016 2 contains 2863 objects located at high Galactic latitudes (|b|>10{\deg}). It includes 85% more sources than previous 3LAC based on years data. AGNs represent least 79% high-latitude in Fermi-Large Source Catalog (4FGL), which covers energy range from 50 MeV to 1 TeV. In addition, 344 gamma-ray are found low latitudes. Most 4LAC blazars (98%),...
The spectra of BL Lac objects and Fanaroff–Riley I radio galaxies are commonly explained by the one-zone leptonic synchrotron self-Compton (SSC) model. Spectral modeling correlated multiwavelength data gives comoving magnetic field strength, bulk outflow Lorentz factor, emission region size. Assuming validity SSC model, Hillas condition shows that only in rare cases such sources accelerate protons to much above 1019 eV, so ≳ 1020 eV ultra-high-energy cosmic rays (UHECRs) likely be heavy ions...
We present radio, optical/NIR, and X-ray observations of the afterglow short-duration 130603B, uncover a break in radio optical bands at 0.5 d after burst, best explained as jet with an inferred opening angle 4-8 deg. GRB 130603B is only third short detection to date, first time that evident band. model temporal evolution spectral energy distribution determine burst explosion properties find isotropic-equivalent kinetic (0.6-1.7) x 10^51 erg circumburst density 5 10^-3-30 cm^-3. From we...
Abstract We present the first extensive radio to γ -ray observations of a fast-rising blue optical transient, AT 2018cow, over its ∼100 days. 2018cow rose few days peak luminosity L pk ∼ 4 × 10 44 erg s −1 , exceeding that superluminous supernovae (SNe), before declining as ∝ t −2 . Initial spectra at δt ≲ 15 were mostly featureless and indicated large expansion velocities v 0.1 c temperatures reaching T 3 K. Later revealed persistent optically thick photosphere emergence H He emission...
Abstract We present deep X-ray and radio observations of the fast blue optical transient (FBOT) AT 2020xnd/ZTF 20acigmel at z = 0.2433 from 13 days to 269 after explosion. 2020xnd belongs category optically luminous FBOTs with similarities archetypal event 2018cow. shows emission reaching L ν ≈ 8 × 10 29 erg s −1 Hz 20 GHz 75 post-explosion, accompanied by rapidly fading soft peaking X 6 42 . Interpreting in context synchrotron radiation explosion’s shock interaction environment, we find...
To take advantage of the astrophysical potential Gamma-Ray Bursts (GRBs), Chinese and French astrophysicists have engaged SVOM mission (Space-based multi-band astronomical Variable Objects Monitor). Major advances in GRB studies resulting from synergy between space ground observations, implements instrumentation. The scientific objectives put a special emphasis on two categories GRBs: very distant GRBs at z$>$5 which constitute exceptional cosmological probes, faint/soft nearby allow...
We present the detection of persistent soft X-ray radiation with L_x ~ 10^41-10^42 erg/s at location extremely luminous, double-humped transient ASASSN-15lh as revealed by Chandra and Swift. interpret this finding in context observations from our multiwavelength campaign, which presence weak narrow nebular emission features host-galaxy nucleus clear differences respect to superluminous supernova optical spectra. Significant UV flux variability on short time-scales detected time...
[Abridged] Context: We present a systematic X-ray spectral-timing study of the recently discovered, exceptionally bright black hole binary system MAXI J1820+070. Our analysis focuses on first part 2018 outburst, covering rise throughout hard state, and hard-intermediate states, transition to soft-intermediate state. Aims: address issue constraining geometry innermost accretion flow its evolution an outburst. Methods: employed two independent methods applied NICER data identified tracked...
We report the $\gamma$-ray detection of a young radio galaxy, PKS 1718$-$649, belonging to class Compact Symmetric Objects (CSOs), with Large Area Telescope (LAT) on board {\it Fermi} satellite. The third Gamma-ray LAT catalog (3FGL) includes an unassociated source, 3FGL J1728.0$-$6446, located close 1718$-$649. Using latest Pass 8 calibration, we confirm that best fit $1 \sigma$ position source is compatible location Cross-matching positions blazar sources from several catalogs yields...
We present the results from a sensitive X-ray survey of 26 nearby hydrogen-poor superluminous supernovae (SLSNe-I) with Swift, Chandra and XMM. This dataset constrains SLSN evolution few days until ~2000 after explosion, reaching luminosity L_x~10^40 erg/s revealing presence significant emission at location PTF12dam. No SLSN-I is detected above L_x~10^41 erg/s, suggesting that luminous L_x~10^45 associated SCP60F6 not common among SLSNe-I. constrain off-axis GRB jets, ionization breakouts...
The energy source powering the extreme optical luminosity of hydrogen-stripped Superluminous Supernovae (SLSNe-I) is not known, but recent studies have highlighted case for a central engine. Radio and/or X-ray observations are best placed to track fastest ejecta and probe presence outflows from We compile all published radio SLSNe-I date present three new two SLSNe-I. None were detected. Through modeling emission, we constrain sub-parsec environments possible in In this sample rule out...
We present the results of first X-ray study a sample 16 young radio sources classified as Compact Symmetric Objects (CSOs). observed six them for time in X-rays using {\it Chandra}, re-observed four with previous XMM-Newton} or Beppo-SAX} data, and included other archival data. All are nearby, $z<1$ age their structures ($<3000$~years) derived from hotspots advance velocity. Our show heterogeneous nature CSOs indicating complex environment associated sources. The covers range luminosity,...
Compact Symmetric Objects (CSOs) show radio features such as jets, lobes, hot spots that are contained within the central 1 kpc region of their host galaxy. Thus, they thought to be among progenitors large-scale galaxies. A debate on whether CSOs compact primarily because young or surrounded by a dense medium impacting expansion is ongoing. Until now, attempts discriminate between environmental and genuine youthfulness scenarios have been inconclusive. We present study three selected basis...
According to radiative models, radio galaxies and quasars are predicted produce gamma rays from the earliest stages of their evolution. Exploring high-energy emission is crucial for providing information on most energetic processes, origin structure newly born jets. Taking advantage more than 11 years \textit{Fermi}-LAT data, we investigate gamma-ray 162 young sources (103 59 quasars), largest sample used so far such a study. We separately analyze each source perform first stacking analysis...
Abstract With enough X-ray flux to be detected in a 160 s scan by SRG/eROSITA, the z = 6.19 quasar CFHQS J142952+544717 is, far, most luminous source known at > 6. We present deep (245 ks) NuSTAR observations of this source; with ∼180 net counts combined observations, is distant object ever observed observatory. Fortuitously, was independently Chandra ∼110 days earlier, enabling identification two nearby (30″ and 45″ away), fainter sources. jointly fit both observations—self-consistently...
With enough X-ray flux to be detected in a 160s scan by SRG/eROSITA, the $z = 6.19$ quasar CFHQS J142952+544717 is, far, most luminous source known at > 6$. We present deep (245 ks) NuSTAR observations of this source; with $\sim180$ net counts combined observations, is distant object ever observed observatory. Fortuitously, was independently Chandra $\sim110$ days earlier, enabling identification two nearby (30'' and 45'' away), fainter sources. jointly fit both...
Abstract Understanding the formation mechanisms of stellar-mass black hole X-ray binaries (BHXBs) remains a fundamental challenge in astrophysics. The natal kick velocities imparted during (BH) provide crucial constraints on these channels. In this work, we present new-epoch very long baseline interferometry (VLBI) observation Galactic BHXB AT2019wey carried out 2023. Combining with archival VLBI data from 2020, successfully measure proper motion over 3 yr timescale, namely, 0.78 ± 0.12 mas...
Compact symmetric objects (CSOs) are intrinsically compact extragalactic radio sources that thought to be the progenitors of classical galaxies. To date, evolutionary models have mainly focused on formation and growth high-power sources, leaving unanswered many questions related low-power objects, whose relativistic jets likely more prone instabilities. We present a new sample candidate CSOs selected from Faint Images Radio Sky at Twenty-cm (FIRST) survey. The main selection criteria (i)...
Abstract We present the results from our extensive hard-to-soft X-ray (NuSTAR, Swift-XRT, XMM-Newton, Chandra) and meter-to-millimeter-wave radio (Giant Metrewave Radio Telescope, Very Large Array, NOEMA) monitoring campaign of very nearby ( d = 6.9 Mpc) Type II supernova (SN) 2023ixf spanning ≈4–165 days post-explosion. This unprecedented data set enables inferences on explosion’s circumstellar medium (CSM) density geometry. In particular, we find that luminous emission is well modeled by...
We investigate the contribution of beamed jet component to high-energy emission in young and compact extragalactic radio sources, focusing for first time on γ-ray band. derive predictions luminosities associated with relativistic assuming a leptonic radiative model. The is produced via Compton scattering by electrons spherical region at considered scales (≲10 kpc). Simulations show wide range luminosities, intensities up ∼1046–1048 erg s−1 depending assumed parameters. find highly linear...
Abstract We present comprehensive observations and analysis of the energetic H-stripped SN 2016coi (a.k.a. ASASSN-16fp), spanning γ -ray through optical radio wavelengths, acquired within first hours to ∼420 days post explosion. Our observational campaign confirms identification He in supernova (SN) ejecta, which we interpret be caused by a larger mixing Ni into outer ejecta layers. By modeling broad bolometric light curve, derive large ejecta-mass-to-kinetic-energy ratio ( M ej ∼ 4–7 ⊙ , E...
Abstract We present the X-ray monitoring campaign of AT2022tsd in time range δ t rest = 23–116 days rest-frame since discovery. With an initial 0.3–10 keV luminosity L x ≈ 10 44 erg s −1 at 23 days, is most luminous FBOT to date and rivals GRBs. find no statistical evidence for spectral evolution. The average spectrum well-described by absorbed simple power-law model with best-fitting photon index <?CDATA ${\rm{\Gamma }}={1.89}_{-0.08}^{+0.09}$?> <mml:math...
Aims. Compact symmetric objects (CSOs) are thought to represent the first step in evolutionary path of radio galaxies. In present study, we investigated X-ray emission two CSOs confirmed emit at GeV energies: PKS 1718–649 and TXS 1146+596. Unveiling origin their observed high-energy is crucial establishing physical parameters source understanding how interact with surrounding medium. Methods. We combined archival new NuSTAR observations 1146+596 have broadband coverage. For both sources,...
Abstract We present the first deep X-ray observations of luminous fast blue optical transient (LFBOT) AT 2018cow at ∼3.7 yr since discovery, together with reanalysis observation δ t ∼ 220 days. emission is significantly detected a location consistent 2018cow. The very soft spectrum and sustained luminosity are distinct from spectral temporal behavior LFBOT in ∼100 days would possibly signal emergence new component, although robust association can only be claimed days, while 1350...
Abstract X-ray continuum emission of active galactic nuclei (AGNs) may be reflected by circumnuclear dusty tori, producing prominent fluorescence iron lines at frequencies. Here, we discuss the broadband three radio-loud AGNs belonging to class compact symmetric objects (CSOs), with detected narrow Fe K α lines. CSOs have newly born radio jets, forming lobes projected linear sizes order a few hundreds parsecs. We model radio-to- γ -ray spectra in J1407+2827, J1511+0518, and J2022+6137, which...