Alessandro Montanari
A5024712421- Geology and Paleoclimatology Research
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Geological and Geochemical Analysis
- Gamma-ray bursts and supernovae
- Particle physics theoretical and experimental studies
- Astro and Planetary Science
- Planetary Science and Exploration
- Particle Detector Development and Performance
- Astrophysical Phenomena and Observations
- Paleontology and Stratigraphy of Fossils
- Neutrino Physics Research
- earthquake and tectonic studies
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- Geological formations and processes
- Evolution and Paleontology Studies
- Radiation Detection and Scintillator Technologies
- Isotope Analysis in Ecology
- Radio Astronomy Observations and Technology
- Atomic and Subatomic Physics Research
- Geochemistry and Elemental Analysis
- Nuclear Physics and Applications
- Galaxies: Formation, Evolution, Phenomena
- Methane Hydrates and Related Phenomena
Istituto Nazionale di Fisica Nucleare, Sezione di Bologna
2002-2024
Geological Observatory of Coldigioco
2014-2024
Heidelberg University
2023-2024
Heidelberg University
2024
Université Paris-Saclay
2021-2023
CEA Paris-Saclay
2021-2023
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2021-2023
University of Würzburg
2023
Max Planck Institute for Physics
2023
École Polytechnique
2023
SS 433 is a microquasar, stellar binary system that launches collimated relativistic jets. We observed in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift apparent position of gamma-ray emission from parsec-scale These observations trace energetic electron population indicate inverse Compton scattering mechanism rays. Our modeling morphology constrains location particle acceleration requires abrupt deceleration jet flow. infer presence...
(40)Ar/(39)Ar dating of drill core samples a glassy melt rock recovered from beneath massive impact breccia contained within the 180-kilometer subsurface Chicxulub crater in Yucatán, Mexico, has yielded well-behaved incremental heating spectra with mean plateau age 64.98 +/- 0.05 million years ago (Ma). The andesitic composition was obtained 9 (1390 to 1393 meters) 1 well. is virtually indistinguishable ages on tektite glass Beloc, Haiti, and Arroyo el Mimbral, northeastern 65.01 0.08 Ma...
Research Article| November 01, 1983 Spheroids at the Cretaceous-Tertiary boundary are altered impact droplets of basaltic composition Alessandro Montanari; Montanari 1Department Geology and Geophysics, University California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Richard L. Hay; Hay Walter Alvarez; Alvarez Frank Asaro; Asaro 2Lawrence Berkeley Laboratory, Helen V. Michel; Michel Luis W. Jan Smit 3Geological Institute, Amsterdam, Nieuwe...
Cyclostratigraphy is an important tool for understanding astronomical climate forcing and reading geological time in sedimentary sequences, provided that imprint of insolation variations caused by Earth's orbital eccentricity, obliquity and/or precession preserved (Milankovitch forcing). Numerous stratigraphic paleoclimate studies have applied cyclostratigraphy, but the robustness methodology its dependence on investigator not been systematically evaluated. We developed Intercomparison...
The central region of the Milky Way is one foremost locations to look for dark matter (DM) signatures. We report first results on a search DM particle annihilation signals using new observations from an unprecedented gamma-ray survey Galactic Center (GC) region, ${\it i.e.}$, Inner Galaxy Survey, at very high energies ($\gtrsim$ 100 GeV) performed with H.E.S.S. array five ground-based Cherenkov telescopes. No significant excess found in 2014-2020 dataset and profile likelihood ratio analysis...
Magnetic fields in galaxies and galaxy clusters are believed to be the result of amplification intergalactic seed during formation large-scale structures universe. However, origin, strength, morphology this magnetic field (IGMF) remain unknown. Lower limits on (or indirect detection of) IGMF can obtained from observations high-energy gamma rays distant blazars. Gamma interact with extragalactic background light produce electron-positron pairs, which subsequently initiate electromagnetic...
GRB221009A is the brightest gamma-ray burst ever detected. To probe very-high-energy (VHE, $>$\!100 GeV) emission, High Energy Stereoscopic System (H.E.S.S.) began observations 53 hours after triggering event, when brightness of moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from third, fourth, ninth nights initial GRB detection, applying atmospheric corrections. The combined yield an energy flux limit $\Phi_\mathrm{UL}^{95\%}...
The Crab Nebula is a unique laboratory for studying the acceleration of electrons and positrons through their non-thermal radiation. Observations very-high-energy γ rays from have provided important constraints modelling its broadband emission. We present first fully self-consistent analysis Nebula’s -ray emission between 1 GeV ∼100 TeV, that is, over five orders magnitude in energy. Using open-source software package G AMMAPY , we combined 11.4 yr data Fermi Large Area Telescope 80 h High...
Analyses of pelagic limestones indicate that the flux extraterrestrial helium-3 to Earth was increased for a 2.5-million year (My) period in late Eocene. The enhancement began ∼1 My before and ended ∼1.5 after major impact events produced large Popigai Chesapeake Bay craters ∼36 million years ago. correlation between concentrations helium-3, tracer fine-grained interplanetary dust, impacts indicates abundance Earth-crossing objects dustiness inner solar system were simultaneously but only...
Abstract. The oceans at the time of Cenomanian–Turonian transition were abruptly perturbed by a period bottom-water anoxia. This led to brief but widespread deposition black organic-rich shales, such as Livello Bonarelli in Umbria–Marche Basin (Italy). Despite intensive studies, origin and exact timing this event are still debated. In study, we assess leading hypotheses about inception oceanic anoxia Late Cretaceous greenhouse world providing 6 Myr long astronomically tuned timescale across...
Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they increasingly considered as being responsible a significant fraction of cosmic rays (CRs) accelerated within Milky Way. Westerlund 1, most known young cluster in our Galaxy is prime candidate studying this hypothesis. While very-high-energy $\gamma$-ray source HESS J1646-458 has been detected vicinity 1 past, its association could not be firmly...
The radio galaxy M87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares reported in 2005, 2008, and 2010. Despite extensive studies, the origin of VHE emission yet to be understood. In this study, we investigate spectrum during states high activity, utilizing 20.2$\,$ hours H.E.S.S. observations. Our findings indicate preference for curved spectrum, characterized by log-parabola model with extra-galactic background light (EBL) above 0.3$\,$TeV at 4$\sigma$...
Analyses of marine carbonates through the interval 63.9 to 65.4 million years ago indicate a near-constant flux extraterrestrial helium-3, tracer accretion rate interplanetary dust Earth. This observation indicates that bolide associated with Cretaceous-Tertiary (K-T) extinction event was not accompanied by enhanced solar system dustiness and so could have been member comet shower. The use helium-3 as constant-flux proxy sedimentation implies deposition K-T boundary clay in (10 +/- 2) x...
The onset of Earth's present icehouse climate in the Late Eocene coincides with astronomical events enigmatic causation. At ∼36 Ma ago 90–100 km large Popigai and Chesapeake Bay impact structures formed within ∼10–20 ka. Enrichments 3He coeval sediments also indicate high fluxes interplanetary dust to Earth for ∼2 Ma. Additionally, several medium-sized are known from Eocene. Here we report Italy presence abundant ordinary chondritic chromite grains (63–250 μm) associated ejecta impactor....
Indirect detection opens a unique window for probing thermal dark matter (DM): the same annihilation process that determined relic abundance in early Universe drives present day astrophysical signal. While TeV-scale particles weakly coupled to Standard Model face undoubted challenges from decades of null searches, scenario remains compelling, and simple realizations such as Higgsino DM remain largely unexplored. The fate scenarios could be by gamma-ray observations center Milky Way with...
In July 2021, PKS 1510-089 exhibited a significant flux drop in the high-energy gamma-ray (by factor 10) and optical 5) bands remained this low state throughout 2022. Similarly, polarization source vanished, resulting spectrum being fully explained through steady of accretion disk broad-line region. Unlike aforementioned bands, very-high-energy X-ray fluxes did not exhibit from year to year. This suggests that steady-state originate different emission region than vanished parts jet fluxes....
Abstract The Deep Underground Neutrino Experiment (DUNE) is a next generation experiment aimed to study neutrino oscillation. Its long-baseline configuration will exploit Near Detector (ND) and Far (FD) located at distance of ∼1300 km. FD consist four Liquid Argon Time Projection Chamber (LAr TPC) modules. A Photon Detection System (PDS) be used detect the scintillation light produced inside detector after interactions. PDS based on collectors coupled Silicon Photomultipliers (SiPMs)....
Research Article| August 01, 2000 Global cooling accelerated by early late Eocene impacts? Hubert B. Vonhof; Vonhof 1Free University, Faculty of Earth Sciences, De Boelelaan 1085, 1081 HV Amsterdam, Netherlands Search for other works this author on: GSW Google Scholar Jan Smit; Smit Henk Brinkhuis; Brinkhuis 2Utrecht Laboratory Palaeobotany and Palynology, Budapestlaan 4, 3585 CD Utrecht, Alessandro Montanari; Montanari 3Osservatorio Geologico di Coldigioco, 62020 Frontale (MC), Italy...
Iridium anomalies of Late Eocene age are here reported in sequences from northern Italy and Weddell Sea, Antarctic. We have analyzed 270 samples marly limestones the Eocene/Oligocene boundary stratotype section at Massignano, Italy, ranging 35.6 to 34.5 Ma (NP 18 Zone NP 19/20 Zone). discovered a distinct Ir peak 156 ± 19 parts per trillion (ppt) lower calcareous nannofossil Zone, corresponding mid-lower part foraminiferal P16 top magnetic Chron 16n2. The this anomaly derived several dated...
Frederik Hilgen, Hayfaa Abdul Aziz, David Bice, Silvia Iaccarino, Wout Krijgsman, Klaudia Kuiper, Alessandro Montanari, Isabella Raffi, Elena Turco, Willem-Jan Zachariasse. Episodes 2005;28:6-17. https://doi.org/10.18814/epiiugs/2005/v28i1/001