M. Giroletti
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View article: A Hyperactive Fast Radio Burst Pinpointed in an SMC-like Satellite Host Galaxy
A Hyperactive Fast Radio Burst Pinpointed in an SMC-like Satellite Host Galaxy Open
Precise localizations of fast radio bursts (FRBs) are essential for uncovering their host galaxies and immediate environments. We present the milliarcsecond-precision European VLBI Network localization of FRB 20240114A, a hyperactive repea…
View article: Twenty years of blazar monitoring with the INAF radio telescopes
Twenty years of blazar monitoring with the INAF radio telescopes Open
Context . The extreme variability of blazars, in both timescale and amplitude, is generally explained as the effect of a relativistic jet closely aligned with the observer’s line of sight. Via causality arguments, variability characteristi…
View article: Twenty years of blazar monitoring with the INAF radio telescopes
Twenty years of blazar monitoring with the INAF radio telescopes Open
The extreme variability of blazars, in both timescale and amplitude, is generally explained as the effect of a relativistic jet closely aligned to the observer's line-of-sight. Due to causality arguments, variability characteristics transl…
View article: Combined dark matter search towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS
Combined dark matter search towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS Open
Dwarf spheroidal galaxies (dSphs) are excellent targets for indirect dark matter (DM) searches using gamma-ray telescopes because they are thought to have high DM content and a low astrophysical background. The sensitivity of these searche…
View article: Puzzling Variation of Gamma Rays from the Sun over the Solar Cycle Revealed with Fermi-LAT
Puzzling Variation of Gamma Rays from the Sun over the Solar Cycle Revealed with Fermi-LAT Open
The steady-state gamma-ray emission from the Sun is thought to consist of two emission components due to interactions with Galactic cosmic rays: (1) a hadronic disk component, and (2) a leptonic extended component peaking at the solar edge…
View article: A Systematic Search for MeV–GeV Pulsar Wind Nebulae without Gamma-Ray Detected Pulsars
A Systematic Search for MeV–GeV Pulsar Wind Nebulae without Gamma-Ray Detected Pulsars Open
An increasing number of pulsar wind nebulae (PWNe) are being identified in the TeV band by ground-based Imaging Air Cherenkov Telescopes such that they constitute the dominant source class of Galactic TeV emitters. However, MeV–GeV PWN cou…
View article: Probing multi-band variability and mode switching in the candidate transitional millisecond pulsar 3FGL J1544.6–1125
Probing multi-band variability and mode switching in the candidate transitional millisecond pulsar 3FGL J1544.6–1125 Open
We present the most extensive high-time resolution multi-band campaign to date on the candidate transitional millisecond pulsar (tMSP) 3FGL J1544.6−1125 in the enigmatic sub-luminous disk state with coordinated observations from the radio …
View article: Fermi-LAT Discovery of a Gamma-Ray Outburst from the Peculiar Compact Steep Spectrum Radiogalaxy 3C 216
Fermi-LAT Discovery of a Gamma-Ray Outburst from the Peculiar Compact Steep Spectrum Radiogalaxy 3C 216 Open
3C 216 is an extragalactic radio source classified as a compact steep spectrum (CSS) object, associated with the source 4FGL J0910.0+4257 detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The source e…
View article: Proper Motion and Natal Kick in the Galactic Black Hole X-Ray Binary AT2019wey
Proper Motion and Natal Kick in the Galactic Black Hole X-Ray Binary AT2019wey Open
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 black hole (BH) formation provide crucial constraints on th…
View article: GRB 221009A: The B.O.A.T. Burst that Shines in Gamma Rays
GRB 221009A: The B.O.A.T. Burst that Shines in Gamma Rays Open
We present a complete analysis of Fermi Large Area Telescope (LAT) data of GRB 221009A, the brightest gamma-ray burst (GRB) ever detected. The burst emission above 30 MeV detected by the LAT preceded, by 1 s, the low-energy (<10 MeV) pulse…
View article: Fermi detection of gamma-ray Emission from the Hot Coronae of Radio-quiet Active Galactic Nuclei
Fermi detection of gamma-ray Emission from the Hot Coronae of Radio-quiet Active Galactic Nuclei Open
Relativistic jets around supermassive black holes (SMBHs) are well-known powerful $γ$-ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in $γ$-ray bands is still unknown despite of great …
View article: Radio observations of the ultra-long GRB 220627A reveal a hot cocoon supporting the blue supergiant progenitor scenario
Radio observations of the ultra-long GRB 220627A reveal a hot cocoon supporting the blue supergiant progenitor scenario Open
We present the discovery of the radio afterglow of the most distant ultra-long gamma-ray burst (GRB) detected to date, GRB~220627A at redshift $z=3.084$. Its prompt gamma-ray light curve shows a double-pulse profile, with the pulses separa…
View article: Multi-wavelength picture of the misaligned BL Lac object 3C 371
Multi-wavelength picture of the misaligned BL Lac object 3C 371 Open
Context. The BL Lac object 3C 371 is one of the targets regularly monitored by the Whole-Earth Blazar Telescope (WEBT), a collaboration of observers studying blazar variability on both short and long timescales. Aims. We aim to evaluate th…
View article: Multiwavelength picture of the misaligned BL Lac object 3C 371
Multiwavelength picture of the misaligned BL Lac object 3C 371 Open
The BL Lac object 3C 371 is one of the targets that are regularly monitored by the Whole Earth Blazar Telescope (WEBT) Collaboration to study blazar variability on both short and long timescales. We aim to evaluate the long-term multiwavel…
View article: Periodic Gamma-Ray Modulation of the Blazar PG 1553+113 Confirmed by Fermi-LAT and Multiwavelength Observations
Periodic Gamma-Ray Modulation of the Blazar PG 1553+113 Confirmed by Fermi-LAT and Multiwavelength Observations Open
A 2.1 yr periodic oscillation of the gamma-ray flux from the blazar PG 1553+113 has previously been tentatively identified in ∼7 yr of data from the Fermi Large Area Telescope. After 15 yr of Fermi sky-survey observations, doubling the tot…
View article: Search for Extended GeV Sources in the Inner Galactic Plane
Search for Extended GeV Sources in the Inner Galactic Plane Open
The recent detection of extended $γ$-ray emission around middle-aged pulsars is interpreted as inverse-Compton scattering of ambient photons by electron-positron pairs escaping the pulsar wind nebula, which are confined near the system by …
View article: High-resolution imaging of the evolving bipolar outflows in symbiotic novae: The case of the RS Ophiuchi 2021 nova outburst
High-resolution imaging of the evolving bipolar outflows in symbiotic novae: The case of the RS Ophiuchi 2021 nova outburst Open
Context. The recurrent and symbiotic nova RS Ophiuchi (RS Oph) underwent a new outburst phase during August 2021, about 15 years after the last event that occurred in 2006. This outburst represents the first nova event ever detected at ver…
View article: A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour
A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour Open
Context. Blazars are beamed active galactic nuclei (AGNs) known for their strong multi-wavelength variability on timescales ranging from years down to minutes. Many different models have been proposed to explain this variability. Aims. We …
View article: A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour
A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour Open
Blazars are beamed active galactic nuclei known for their strong multi-wavelength variability on timescales from years down to minutes. We aim to investigate the suitability of the twisting jet model presented in previous works to explain …
View article: Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode
Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode Open
Context. The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (M…
View article: The Northern Cross Fast Radio Burst project
The Northern Cross Fast Radio Burst project Open
Context. Fast radio bursts (FRBs) are energetic, millisecond-duration radio pulses observed at extragalactic distances and whose origins are still a subject of heated debate. A fraction of the FRB population have shown repeating bursts, ho…
View article: High-resolution imaging of the evolving bipolar outflows in symbiotic novae: The case of the RSOphiuchi 2021 nova outburst
High-resolution imaging of the evolving bipolar outflows in symbiotic novae: The case of the RSOphiuchi 2021 nova outburst Open
The recurrent and symbiotic nova RS Ophiuchi (RSOph) underwent a new outburst phase during August 2021, about 15 years after the last event that occurred in 2006. This outburst represents the first nova event ever detected at very high ene…
View article: Revealing faint compact radio jets at redshifts above 5 with very long baseline interferometry
Revealing faint compact radio jets at redshifts above 5 with very long baseline interferometry Open
Over the past two decades, our knowledge of the high-redshift (z > 5) radio quasars has expanded, thanks to dedicated high-resolution very long baseline interferometry (VLBI) observations. Distant quasars provide unique information about t…
View article: A JVLA, LOFAR, e-Merlin, VLBA, and EVN study of RBS 797: can binary supermassive black holes explain the outburst history of the central radio galaxy?
A JVLA, LOFAR, e-Merlin, VLBA, and EVN study of RBS 797: can binary supermassive black holes explain the outburst history of the central radio galaxy? Open
Aims. The multifaceted central radio galaxy of the cluster RBS 797 shows several episodes of jet activity in multiple directions. We wish to understand the causes behind these dramatic misalignments and measure the timescales of the succes…
View article: A JVLA, LOFAR, e-Merlin, VLBA and EVN study of RBS 797: can binary SMBHs explain the outburst history of the central radio galaxy?
A JVLA, LOFAR, e-Merlin, VLBA and EVN study of RBS 797: can binary SMBHs explain the outburst history of the central radio galaxy? Open
We present a multi-frequency (144 MHz - 9 GHz) and multi-scale (5 pc - 50 kpc) investigation of the central radio galaxy in RBS 797, by means of JVLA, LOFAR (with international stations), e-Merlin, VLBA and EVN data. We investigate the mor…
View article: Investigating X-ray Emission in the GeV-emitting Compact Symmetric Objects PKS 1718-649 and TXS 1146+596
Investigating X-ray Emission in the GeV-emitting Compact Symmetric Objects PKS 1718-649 and TXS 1146+596 Open
Compact Symmetric Objects (CSOs) are thought to represent the first step in the evolutionary path of radio galaxies. In this work, we investigate the X-ray emission of two CSOs confirmed to emit at GeV energies: PKS 1718-649 and TXS 1146+5…
View article: $Fermi$-LAT follow-up observations in seven years of real-time high-energy neutrino alerts
$Fermi$-LAT follow-up observations in seven years of real-time high-energy neutrino alerts Open
The realtime program for high-energy neutrino track events detected by the IceCube South Pole Neutrino Observatory releases alerts to the astronomical community with the goal of identifying electromagnetic counterparts to astrophysical neu…
View article: Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode
Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode Open
The nearby elliptical galaxy M87 contains one of the only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) f…
View article: TELAMON: Effelsberg monitoring of AGN jets with very-high-energy astroparticle emission - I. Program description and sample characterization
TELAMON: Effelsberg monitoring of AGN jets with very-high-energy astroparticle emission - I. Program description and sample characterization Open
Aims. We introduce the TELAMON program which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, specifically TeV blazars and candidate neutrino-asso…
View article: Milliarcsecond Localisation of the Hyperactive Repeating FRB 20220912A
Milliarcsecond Localisation of the Hyperactive Repeating FRB 20220912A Open
We present very-long-baseline interferometry (VLBI) observations of the hyperactive repeating FRB 20220912A using the European VLBI Network (EVN) with an EVN-Lite setup. We detected 150 bursts from FRB 20220912A over two observing epochs i…