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Tatischeff, Vincent, e Stefano Gabici. "Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements". Annual Review of Nuclear and Particle Science 68, n.º 1 (19 de outubro de 2018): 377–404. http://dx.doi.org/10.1146/annurev-nucl-101917-021151.
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In this review, we first reassess the supernova remnant paradigm for the origin of Galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light-element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured beryllium abundances in old halo stars of low metallicity with the standard model of the Galactic cosmic-ray origin. We then discuss the various cosmic-ray models proposed in the literature to account for the measured evolution of the light elements in the Milky Way, and point out the difficulties that they all encounter. It seems to us that, among all possibilities, the superbubble model provides the most satisfactory explanation for these observations.
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BARBIERI, JAMES, GEORGE CHAPLINE e DAVID I. SANTIAGO. "QUANTUM CRITICALITY, EVENT HORIZONS AND COSMIC GAMMA RAY BURSTS". Modern Physics Letters A 18, n.º 39 (21 de dezembro de 2003): 2767–73. http://dx.doi.org/10.1142/s0217732303012489.
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The logical inconsistency of quantum mechanics and general relativity can be avoided if the relativity principle fails for length scales smaller than the quantum coherence length for the vacuum state. This has dramatic consequences for the phenomenology of compact astrophysical objects. If we assume that at the Planck scale elementary particles interact via a universal four-point interaction and baryon number conservation is violated, then nucleons approaching an event horizon surface can disintegrate into gamma rays and high energy leptons. Integrating the Altarelli–Parisi equations to find the Planck scale parton distribution function for a nucleon, we find that nucleon decays produce a fluorescence gamma ray spectrum strikingly similar to that observed for cosmic gamma ray bursts.
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Fiorillo, Damiano F. G., Mauricio Bustamante e Victor B. Valera. "Near-future discovery of point sources of ultra-high-energy neutrinos". Journal of Cosmology and Astroparticle Physics 2023, n.º 03 (1 de março de 2023): 026. http://dx.doi.org/10.1088/1475-7516/2023/03/026.
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Abstract Upcoming neutrino telescopes may discover ultra-high-energy (UHE) cosmic neutrinos, with energies beyond 100 PeV, in the next 10–20 years. Finding their sources would identify guaranteed sites of interaction of UHE cosmic rays, whose origin is unknown. We search for sources by looking for multiplets of UHE neutrinos arriving from similar directions. Our forecasts are state-of-the-art, geared at neutrino radio-detection in IceCube-Gen2. They account for detector energy and angular response, and for critical, but uncertain backgrounds. Sources at declination of -45° to 0° will be easiest to discover. Discovering even one steady-state source in 10 years would imply that the source has an UHE neutrino luminosity at least larger than about 1043 erg/s (depending on the source redshift evolution). Discovering no transient source would disfavor transient sources brighter than 1053 erg as dominant. Our results aim to inform the design of upcoming detectors.
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SALTZBERG, DAVID, Katsushi Arisaka, Ron Bain, Steven Barwick, James Beatty, David Besson, W. Robert Binns et al. "INTRODUCTION TO THE SALSA, A SALTDOME SHOWER ARRAY AS A GZK NEUTRINO OBSERVATORY". International Journal of Modern Physics A 21, supp01 (julho de 2006): 252–53. http://dx.doi.org/10.1142/s0217751x06033726.
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The observed spectrum of ultra-high energy cosmic rays virtually guarantees the presence of ultra-high energy neutrinos due to their interaction with the cosmic microwave background. Every one of these neutrinos will point back to its source and, unlike cosmic rays, will arrive at the Earth unattenuated, from sources perhaps as distant as z =20. The neutrino telescopes currently under construction, should discover a handful of these events, probably too few for detailed study. In this talk I will describe how an array of VHF and UHF antennas embedded in a large salt dome, SalSA (Saltdome Shower Array) promises to yield a teraton detector (> 500 km3-sr) for contained neutrino events with energies above 1017 eV. Our simulations show that such a detector may observe several hundreds of these neutrinos over its lifetime. Our simulations also show how such interactions will provide high energy physicists with an energy frontier for weak interactions an order-of-magnitude larger than that of the LHC. The flavor ID capalities of SALSA, combined with the extreme L/E of these neutrinos, will provide a window on neutrino oscillations and decay times eight orders of magnitude higher than laboratory experiments. In addition to the latest simulation results, we describe progress on detectors and site selection.
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de Naurois, Mathieu. "TeV observations of the Galactic center and starburst galaxies". Proceedings of the International Astronomical Union 9, S303 (outubro de 2013): 29–42. http://dx.doi.org/10.1017/s1743921314000118.
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AbstractThe vicinity of the Galactic center harbors many potential accelerators of cosmic rays (CR) that could shine in very-high-energy (VHE) γ-rays, such as pulsar wind nebulae, supernova remnants, binary systems and the central black hole Sgr A*, and is characterized by high gas density, large magnetic fields and a high rate of starburst activity similar to that observed in the core of starburst galaxies. In addition to these astrophysical sources, annihilation of putative WIMPs concentrated in the gravitational well could lead to significant high-energy emission at the Galactic center. The Galactic center region has been observed by atmospheric Cherenkov telescopes, and in particular by the H. E. S. S. array in Namibia for the last ten years above 150 GeV. This large data set, comprising more than 200 hours of observations, led to the discovery of a point-like source spatially compatible with the supermassive black hole Sgr A*, and to an extended diffuse emission, correlated with molecular clouds and attributed to the interaction of cosmic rays with the interstellar medium. Over the same time period, two starburst galaxies, namely M 82 and NGC 253, were detected at TeV energies after very deep exposures. Results from these ten years of observations of the Galactic center region and starburst galaxies at TeV energies are presented, and implications for the various very-high-energy emission mechanisms are discussed.
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Barlykov, N., V. Dudin, T. Enik, A. Ivanov, E. Kokoulina, A. Kutov, E. Martovitski, V. Nikitin e V. Popov. "MiniSPD Stand for Testing Si-Detectors". Nonlinear Phenomena in Complex Systems 25, n.º 3 (17 de outubro de 2022): 254–65. http://dx.doi.org/10.33581/1561-4085-2022-25-3-254-265.
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SPD (Spin Physics Detector) collaboration proposes to install a universal setup in the second interaction point of the NICA collider under construction (JINR, Dubna) to study the spin structure of the proton and deuteron. It plans to carry out research of spin-related phenomena with polarized proton and deuteron beams at a collision energy up to 27 GeV and a luminosity up to 1032 cm−2 s−1. MiniSPD stand is manufactured as a setup for testing SPD detector prototypes with cosmic muons at LHEP. It allows to carry out checkout of the Data Acquisition System (DAQ), the Detector Control System (DCS). Young physicists and students working at this test bench gain experience of work with real detectors of the future SPD setup. In this report, we give some information about the basic tasks of SPD projects. The results of simulation and comparison with data on cosmic rays at this stand for three modules of silicon plates are also presented.
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Gusev, А. I., e O. I. Guseva. "NEMESIS APPROXIMATED TO SUN". Globus 7, n.º 2(59) (4 de abril de 2021): 4–11. http://dx.doi.org/10.52013/2658-5197-59-2-1.
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Photographs of double Sun lead in paper that it took off with Prohodnaja Griva of Gornyy Altay (near c. Belokurikha). Evidences of approaching second Sun – Nemesis to our Shine. Influence of Nemesis on the cosmic events in Sun system are very impression that its testify about interaction of two stars and influence second Sun on the planets of Sun system. Powerful emissions of plasma in view concentration rays with side of our Sun and separation blue spectrums clots with Nemesis that it point on the essential helium component. Myself Nemesis can to be carry to class B – white-blue giants. Anomaly movements of magnet poles of Earth call by impact of Nemesis and can be result to reserve polarity on the Earth.
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Fehérkuti, Anna, Gábor I. Veres, Ralf Ulrich e Tanguy Pierog. "Feasibility Studies of Charge Exchange Measurements in pp Collisions at the LHC". Entropy 24, n.º 9 (25 de agosto de 2022): 1188. http://dx.doi.org/10.3390/e24091188.
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(1) Pions produced in the development of extended atmospheric cosmic ray air showers subsequently decay to muons. The measured yield of those muons is generally underestimated by current phenomenological models and event generators optimized for cosmic ray physics. The importance of those disagreements motivates the feasibility studies for testing these models at the Large Hadron Collider (LHC) energies, at the highest center-of-mass energies achievable in a laboratory. The interaction of a nucleus and a virtual pion created in a charge exchange reaction at the LHC is a similar process to those contributing to the development of air showers in case of cosmic rays. The crucial problem of such an analysis is the selection of charge exchange events with the highest possible efficiency and high purity from proton–proton collisions at the LHC. (2) For this we consider distributions of various measurable quantities given by event generators commonly used in cosmic ray physics. (3) We examine the expected distributions of energy deposited in different calorimeters of an LHC experiment. We consider the geometrical acceptance and energy resolution of the detectors at the Compact Muon Solenoid (CMS) experiment, as an example. We determine a working point cut from the various options for event selection, and compare signal and background predictions using different models for a representative simple observable, such as average transverse momentum or charge particle yield. (4) A set of event selection cuts along these considerations is proposed, with the aim of achieving optimal efficiency and purity.
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Chalov, S. V., H. J. Fahr e Y. G. Malama. "Unexpected sites of efficient stochastic acceleration in the inner heliosheath". Annales Geophysicae 25, n.º 3 (29 de março de 2007): 575–80. http://dx.doi.org/10.5194/angeo-25-575-2007.
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Abstract. Up until the recent past, it was generally believed that the solar wind termination shock (TS) is the favourite site to accelerate ions from the keV- to the MeV- energy levels by means of Fermi-1 processes. When Voyager 1 was crossing the TS at the end of 2004, the registrations of this spacecraft showed, however, that beyond the shock passage fluxes of anomalous cosmic rays kept increasing with time. This obviously called for an acceleration site further downstream of the shock in the heliosheath which had not been identified before. In this paper we thus investigate the process of energy diffusion due to wave-particle interactions (Fermi-2) operating on pick-up ions which are convected downstream of the TS with the subsonic solar wind. We investigate the continuous effect of stochastic acceleration processes suffered by pick-up ions at their interaction with heliosheath turbulences, while they are slowly convected with the subsonic solar wind towards the heliotail. As we can show, the inner heliosheath region, with an extent of about 100 AU around the solar wind stagnation point, is specifically favourable for the energy processing of pick-up ions by Fermi-2 processes up to MeV energies. In addition, we claim that this region is the origin of multiply-charged anomalous cosmic ray particles that have been registered in recent times.
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Nam, J. W., C. C. Chen, C. H. Chen, C. W. Chen, P. Chen, Y. C. Chen, S. Y. Hsu et al. "Design and implementation of the TAROGE experiment". International Journal of Modern Physics D 25, n.º 13 (novembro de 2016): 1645013. http://dx.doi.org/10.1142/s0218271816450139.
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Taiwan astroparticle radiowave observatory for geo-synchrotron emissions (TAROGE) is an antenna array on the high mountains of Taiwan’s east coast for the detection of ultra-high energy cosmic rays (UHECRs) in an energy above [Formula: see text] eV. The antennas point toward the ocean to detect radiowave signals emitted by the UHECR-induced air-shower as a result of its interaction with the geomagnetic field. Looking down from the coastal mountain, the effective area is enhanced by collecting both direct-emission as well as the ocean-reflected signals. This instrument also provides the capability of detecting earth-skimming tau-neutrino through its subsequent tau-decay induced shower. In order to prove the detection concept, initial two stations were successfully built at 1000 m elevation near Heping township, Taiwan, in 2014–2015. Each station consists of 12 log-periodic dipole array antennas for 110–300 MHz. The stations have been operating smoothly for radio survey and optimization of instrumental parameters. In this report, we discuss the design of TAROGE, the performance of the prototype station and the future prospect.
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Kulikovskiy, Vladimir. "ANTARES and KM3NeT programs for the supernova neutrino detection". Proceedings of the International Astronomical Union 12, S331 (fevereiro de 2017): 339–44. http://dx.doi.org/10.1017/s1743921317004495.
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AbstractThe currently working ANTARES neutrino telescope has capabilities to detect neutrinos produced in astrophysical transient sources. Neutrino alerts are regularly generated to trigger multi-wavelength observatories. Potential sources include gamma-ray bursts, core-collapse supernovae, and flaring active galactic nuclei. In particular, the neutrino detection together with the multi-wavelength observations may reveal hidden jets in the supernova explosions.Supernovae remnants are currently the most promising acceleration sites of the cosmic rays in our Galaxy. The neutrino emission is expected during the cosmic ray interaction with the surrounding matter. The neutrino telescopes in the Northern hemisphere have excellent visibility to the most of the galactic supernovae remnants. Recent results on the search for point-sources with the ANTARES detector and the prospects for the future KM3NeT detector are presented.Although ANTARES and KM3NeT detectors are mainly designed for high energy neutrino detection, the MeV neutrino signal from the supernova can be identified as a simultaneous increase of the counting rate of the optical modules in the detector. The noise from the optical background due to 40K decay in the sea water and the bioluminescence can be significantly reduced by using nanosecond coincidences between the nearby placed photomultipliers. This technique has been tested with the ANTARES storeys, each one consisting of three 10-inch photomultipliers, and it is further optimized for the KM3NeT telescope where the directional optical modules containing 31 3-inch photomultipliers provide very promising expectations.
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Pais, Matteo, Christoph Pfrommer, Kristian Ehlert, Maria Werhahn e Georg Winner. "Constraining the coherence scale of the interstellar magnetic field using TeV gamma-ray observations of supernova remnants". Monthly Notices of the Royal Astronomical Society 496, n.º 2 (12 de junho de 2020): 2448–61. http://dx.doi.org/10.1093/mnras/staa1678.
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ABSTRACT Galactic cosmic rays (CRs) are believed to be accelerated at supernova remnant (SNR) shocks. In the hadronic scenario, the TeV gamma-ray emission from SNRs originates from decaying pions that are produced in collisions of the interstellar gas and CRs. Using CR-magnetohydrodynamic simulations, we show that magnetic obliquity-dependent shock acceleration is able to reproduce the observed TeV gamma-ray morphology of SNRs such as Vela Jr and SN1006 solely by varying the magnetic morphology. This implies that gamma-ray bright regions result from quasi-parallel shocks (i.e. when the shock propagates at a narrow angle to the upstream magnetic field), which are known to efficiently accelerate CR protons, and that gamma-ray dark regions point to quasi-perpendicular shock configurations. Comparison of the simulated gamma-ray morphology to observations allows us to constrain the magnetic coherence scale λB around Vela Jr and SN1006 to $\lambda _B \simeq 13_{-4.3}^{+13}$ pc and $\lambda _B \gt 200_{-40}^{+50}$ pc, respectively, where the ambient magnetic field of SN1006 is consistent with being largely homogeneous. We find consistent pure hadronic and mixed hadronic-leptonic models that both reproduce the multifrequency spectra from the radio to TeV gamma-rays and match the observed gamma-ray morphology. Finally, to capture the propagation of an SNR shock in a clumpy interstellar medium, we study the interaction of a shock with a dense cloud with numerical simulations and analytics. We construct an analytical gamma-ray model for a core collapse SNR propagating through a structured interstellar medium, and show that the gamma-ray luminosity is only biased by 30 per cent for realistic parameters.
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Sahakyan, N. "Origin of the multiwavelength emission of PKS 0502+049". Astronomy & Astrophysics 622 (fevereiro de 2019): A144. http://dx.doi.org/10.1051/0004-6361/201834606.
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The origin of the multiwavelength emission from PKS 0502+049 neighboring the first cosmic neutrino source TXS 0506+056 is studied using the data observed byFermi-Large Area Telescope andSwiftUltraViolet/Optical Telescope and X-Ray Telescope. This source was in a flaring state in the considered bands before and after the neutrino observations in 2014–2015, characterized by hard emission spectra in the X-ray andγ-ray bands, ≃1.5 − 1.8 and ≤2.0, respectively. During the neutrino observations, theγ-ray spectrum shows a deviation from a simple power-law shape, indicating a spectral cutoff atEc = 8.50 ± 2.06 GeV. The spectral energy distributions of PKS 0502+049 are modeled within a one-zone leptonic scenario assuming that high energyγ-ray emission is produced either by inverse Compton scattering of synchrotron or dusty torus photons by the electron population that produce the radio-to-optical emission. Alternatively, the observedγ-rays are modeled considering inelastic interaction of protons, when the jet interacts with a dense gaseous target. During the neutrino observations, theγ-ray data are best described when the proton energy distribution is ∼E−2.61pand if the protons are effectively accelerated up to 10 PeV, the expected neutrino rate is ∼1.1 events within 110 days. In principle, if theγ-ray emission with a hard photon index observed during the flaring periods extends up to teraelectronvolt energies, the expected rate can be somewhat higher, but such conditions are hardly possible. Within the hadronic interpretation, theγ-ray data can be reproduced only when the accretion rate of PKS 0502+049 is in the super-Eddington regime, as opposed to the leptonic scenario. From the point of view of the necessary energetics, as well as considering that the required parameters are physically reasonable, when the neutrinos were observed the broadband emission from PKS 0502+049 was most likely of a leptonic origin.
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Dell’Ova, P., A. Gusdorf, M. Gerin, D. Riquelme, R. Güsten, A. Noriega-Crespo, L. N. Tram et al. "Interstellar anatomy of the TeV gamma-ray peak in the IC443 supernova remnant". Astronomy & Astrophysics 644 (dezembro de 2020): A64. http://dx.doi.org/10.1051/0004-6361/202038339.
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Context. Supernova remnants (SNRs) represent a major feedback source from stars in the interstellar medium of galaxies. During the latest stage of supernova explosions, shock waves produced by the initial blast modify the chemistry of gas and dust, inject kinetic energy into the surroundings, and may alter star formation characteristics. Simultaneously, γ-ray emission is generated by the interaction between the ambient medium and cosmic rays (CRs), including those accelerated in the early stages of the explosion. Aims. We study the stellar and interstellar contents of IC443, an evolved shell-type SNR at a distance of 1.9 kpc with an estimated age of 30 kyr. We aim to measure the mass of the gas and characterize the nature of infrared point sources within the extended G region, which corresponds to the peak of γ-ray emission detected by VERITAS and Fermi. Methods. We performed 10′ × 10′ mapped observations of 12CO, 13CO J = 1–0, J = 2–1, and J = 3–2 pure rotational lines, as well as C18O J = 1–0 and J = 2–1 obtained with the IRAM 30 m and APEX telescopes over the extent of the γ-ray peak to reveal the molecular structure of the region. We first compared our data with local thermodynamic equilibrium models. We estimated the optical depth of each line from the emission of the isotopologs 13CO and C18O. We used the population diagram and large velocity gradient assumption to measure the column density, mass, and kinetic temperature of the gas using 12CO and 13CO lines. We used complementary data (stars, gas, and dust at multiple wavelengths) and infrared point source catalogs to search for protostar candidates. Results. Our observations reveal four molecular structures: a shocked molecular clump associated with emission lines extending between −31 and 16 km s−1, a quiescent, dark cloudlet associated with a line width of ~2 km s−1, a narrow ring-like structure associated with a line width of ~1.5 km s−1, and a shocked knot. We measured a total mass of ~230, ~90, ~210, and ~4 M⊙, respectively, for the cloudlet, ring-like structure, shocked clump, and shocked knot. We measured a mass of ~1100 M⊙ throughout the rest of the field of observations where an ambient cloud is detected. We found 144 protostar candidates in the region. Conclusions. Our results emphasize how the mass associated with the ring-like structure and the cloudlet cannot be overlooked when quantifying the interaction of CRs with the dense local medium. Additionally, the presence of numerous possible protostars in the region might represent a fresh source of CRs, which must also be taken into account in the interpretation of γ-ray observationsin this region.
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Clark, J. S., B. W. Ritchie e I. Negueruela. "A VLT/FLAMES survey for massive binaries in Westerlund 1". Astronomy & Astrophysics 635 (março de 2020): A187. http://dx.doi.org/10.1051/0004-6361/201935903.
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Context. The formation, properties, and evolution of massive stars remain subject to considerable theoretical and observational uncertainty. This impacts on fields as diverse as galactic feedback, the production of cosmic rays, and the nature of the progenitors of both electromagnetic and gravitational wave transients. Aims. The young massive clusters many such stars reside within provide a unique laboratory for addressing these issues. In this work we provide a comprehensive stellar census of Westerlund 1 in order to to underpin such efforts. Methods. We employed optical spectroscopy of a large sample of early-type stars to determine cluster membership for photometrically-identified candidates, characterise their spectral type, and identify new candidate spectroscopic binaries. Results. Sixty nine new members of Westerlund 1 are identified via I-band spectroscopy. Together with previous observations, they illustrate a smooth and continuous morphological sequence from late-O giant through to OB supergiant. Subsequently, the progression bifurcates, with one branch yielding mid-B to late-F hypergiants, and cool supergiants, and the other massive blue stragglers prior to a diverse population of H-depleted WRs. We identify a substantial population of O-type stars with very broad Paschen series lines, a morphology that is directly comparable to known binaries in the cluster. In a few cases additional low-resolution R-band spectroscopy is available, revealing double-lined He I profiles and confirming binarity for these objects; suggesting a correspondingly high binary fraction amongst relatively unevolved cluster members. Conclusions. Our current census remains incomplete, but indicates that Westerlund 1 contains at least 166 stars with initial masses estimated to lie between ∼25 M⊙ and ∼50 M⊙, with more massive stars already lost to supernova. Our data is consistent with the cluster being co-eval, although binary interaction is clearly required to yield the observed stellar population, which is characterised by a uniquely rich cohort of hypergiants ranging from spectral type O to F, with both mass-stripped primaries and rejuvenated secondaries or merger products present. Future observations of Wd1 and similar stellar aggregates hold out the prospect of characterising both single- and binary- evolutionary channels for massive stars and determining their relative contributions. This in turn will permit the physical properties of such objects at the point of core-collapse to be predicted, which is of direct relevance for understanding the formation of relativistic remnants such as the magnetars associated with Wd1 and other young massive clusters.
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Accolla, M., G. Pellegrino, G. A. Baratta, G. G. Condorelli, G. Fedoseev, C. Scirè, M. E. Palumbo e G. Strazzulla. "Combined IR and XPS characterization of organic refractory residues obtained by ion irradiation of simple icy mixtures". Astronomy & Astrophysics 620 (dezembro de 2018): A123. http://dx.doi.org/10.1051/0004-6361/201834057.
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Context. Multi-year laboratory experiments have demonstrated that frozen icy mixtures containing simple organic and inorganic molecules (such as H2O, N2, CH4, CO, CO2, C2H6, etc.), if exposed to a flux of energetic ions or UV photons, give rise to new more complex molecules at low temperatures (10–50 K). A fraction of the new synthesized molecules is volatile while the remaining fraction is refractory and therefore it is preserved after the warm-up of the substrate to room temperature. Moreover, a part of the refractory material is formed during the annealing to room temperature, when molecules and radicals into the processed ice become mobile and react to form non-volatile molecules. By means of similar mechanisms, complex organic materials may be formed on the icy surfaces of some objects in the outer solar system, such as trans-Neptunian objects, comets and some satellites of the giant planets: in fact the interaction with solar wind and solar flares ions, solar photons and galactic cosmic rays could produce more refractory materials, analogous to those produced in the laboratory. In some cases, the materials thus synthesized may contain functional groups considered relevant to the pre-biotic chemistry in the hypothesis that interplanetary dust particles, comets and meteoroids contributed to seed the early Earth with the building blocks of life. Aims. The aim of this work is to investigate the chemical similarities and differences between some organic residues left over after ion bombardment (200 keV H+) of different ice mixtures followed by subsequent warm up under vacuum to room temperature. Methods. Seven organic residues have been prepared in our laboratory following a procedure involving the proton irradiation of seven different icy mixtures and their warm-up to room temperature. All the organic samples were characterized by FTIR spectroscopy with measurements performed in situ, in the ultra-high vacuum condition preventing any sample degradation. Three of them were selected to be characterized by XPS spectroscopy as well. Results. Among the organic residues presented in this paper, only those containing nitrogen and carbon exhibit the multi-component band centred at 2200 cm−1. This multi-component band presents interest from the astrobiological point of view due to its attribution to nitriles (–C≡N) and isonitriles (–N≡C). Our results demonstrate that this band is present in the IR spectra of organic nitrogen residues regardless the use of oxygen-bearing species in the icy mixture. This finding is of interest since the 2200 cm−1 band has been observed in some extraterrestrial samples (micro-meteorites) collected in the Antarctica.
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Stein, Y., R. J. Dettmar, M. Weżgowiec, J. Irwin, R. Beck, T. Wiegert, M. Krause et al. "CHANG-ES". Astronomy & Astrophysics 632 (26 de novembro de 2019): A13. http://dx.doi.org/10.1051/0004-6361/201935558.
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Context. The radio continuum halos of edge-on spiral galaxies have diverse morphologies, with different magnetic field properties and cosmic ray (CR) transport processes into the halo. Aims. Using the Continuum HAloes in Nearby Galaxies – an EVLA Survey (CHANG-ES) radio continuum data from the Karl G. Jansky Very Large Array (VLA) in two frequency bands, 6 GHz (C-band) and 1.5 GHz (L-band), we analyzed the radio properties, including polarization and the transport processes of the CR electrons (CREs), in the edge-on spiral galaxy NGC 4013. Supplementary LOw-Frequency ARray (LOFAR) data at 150 MHz are used to study the low-frequency properties of this galaxy and X-ray data are used to investigate the central region. Methods. We determined the total radio flux densities (central source, disk, halo and total) as well as the radio scale heights of the radio continuum emission at both CHANG-ES frequencies and at the LOFAR frequency. We derived the magnetic field orientation from CHANG-ES polarization data and rotation measure synthesis (RM synthesis). Furthermore, we used the revised equipartition formula to calculate the magnetic field strength. Lastly, we modeled the processes of CR transport into the halo with the 1D SPINNAKER model. Results. The central point source dominates the radio continuum emission with a mean of ∼35% of the total flux density emerging from the central source in both CHANG-ES bands. Complementary X-ray data from Chandra show one dominant point source in the central part. The XMM-Newton spectrum shows hard X-rays, but no clear AGN classification is possible at this time. The radio continuum halo of NGC 4013 in C-band is rather small, while the low-frequency LOFAR data reveal a large halo. The scale height analysis shows that Gaussian fits, with halo scale heights of 1.2 kpc in C-band, 2.0 kpc in L-band, and 3.1 kpc at 150 MHz, better represent the intensity profiles than do exponential fits. The frequency dependence gives clear preference to diffusive CRE transport. The radio halo of NGC 4013 is relatively faint and contributes only 40% and 56% of the total flux density in C-band and L-band, respectively. This is less than in galaxies with wind-driven halos. While the SPINNAKER models of the radio profiles show that advection with a launching velocity of ∼20 km s−1 (increasing to ∼50 km s−1 at 4 kpc height) fits the data equally well or slightly better, diffusion is the dominating transport process up to heights of 1–2 kpc. The polarization data reveal plane-parallel, regular magnetic fields within the entire disk and vertical halo components indicating the presence of an axisymmetric field having a radial component pointing outwards. The mean magnetic field strength of the disk of NGC 4013 of 6.6 μG is rather small. Large-scale vertical fields are observed in the halo out to heights of about 6 kpc. Conclusions. The interaction and the low star formation rate (SFR) across the disk of NGC 4013 probably influence the appearance of its radio continuum halo and are correlated with the low total magnetic field strength. Several observable quantities give consistent evidence that the CR transport in the halo of NGC 4013 is diffusive: the frequency dependence of the synchrotron scale height, the disk/halo flux density ratio, the vertical profile of the synchrotron spectral index, the small propagation speed measured modeled with SPINNAKER, and the low temperature of the X-ray emitting hot gas.
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Sarmah, Prantik, Sovan Chakraborty e Jagdish C. Joshi. "Probing LHAASO galactic PeVatrons through gamma-ray and neutrino correspondence". Monthly Notices of the Royal Astronomical Society, 27 de fevereiro de 2023. http://dx.doi.org/10.1093/mnras/stad609.
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Abstract Recently, Large High Altitude Air Shower Observatory (LHAASO) has detected several Galactic point sources of ultra high energy (UHE; Eγ > 100 TeV) gamma-rays. These gamma-rays are possibly created in leptonic or hadronic interactions of cosmic rays (CRs) of PeV energies. In the hadronic channel (p − p interaction), the gamma-rays are accompanied by neutrinos. The detection of neutrinos is therefore crucial in understanding CR acceleration in such objects. To estimate the neutrino flux, we adopt the two LHAASO sources (J2226+6057, J1908+0621) found to be spatially associated with the Supernova remnants (SNR G106.3+2.7, SNR G40.5-0.5). For these two sources, the detected TeV-PeV gamma-ray spectra are found to be unusually hard (with spectral index ∼ 1.8). We develop a model of gamma-ray and neutrino emission based on the above two prototypes. The neutrino fluxes from these two sources are found to be below the IceCube sensitivity, but are detectable in upcoming IceCube-Gen2 and KM3NeT experiments. We further estimate the neutrino fluxes from similar other 10 LHAASO PeVatron sources and most of them are found to be detectable in IceCube-Gen2 and KM3NeT. Finally, we explore our model parameters, in particular the spectral power law index and estimate the future potential of the neutrino detectors to probe CR acceleration in such Galactic sources.
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Ge, Ting-Ting, Xiao-Na Sun, Rui-Zhi Yang, Yun-Feng Liang e En-Wei Liang. "Diffuse γ-ray emission around the massive star forming region of Carina Nebula Complex". Monthly Notices of the Royal Astronomical Society, 10 de outubro de 2022. http://dx.doi.org/10.1093/mnras/stac2885.
Texto completo da fonteResumo:
Abstract We report the Fermi Large Area Telescope (Fermi-LAT) detection of the γ-ray emission toward the massive star forming region of Carina Nebula Complex (CNC). Using the latest source catalog and diffuse background models, we found that the GeV γ-ray emission in this region can be resolved into three different components. The GeV γ-ray emission from the central point source is considered to originate from the η Carina (η Car). We further found the diffuse GeV γ-ray emission around the CNC which can be modelled by two Gaussian disks with radii of 0.4○ (region A) and 0.75○ (region B), respectively. The GeV γ-ray emission from both the regions A and B have good spatial consistency with the derived molecular gas in projection on the sky. The GeV γ-ray emission of region A reveals a characteristic spectral shape of the pion-decay process, which indicates that the γ-rays are produced by the interactions of hadronic cosmic rays with ambient gas. The γ-rays spectrum of region B has a hard photon index of 2.12±0.02, which is similar to other young massive star clusters. We argue that the diffuse GeV γ-ray emission in region A and region B likely originate from the interaction of accelerated protons in clusters with the ambient gas.
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Yeung, Paul K. H., Aya Bamba e Hidetoshi Sano. "Multiwavelength studies of G298.6−0.0: An old GeV supernova remnant interacting with molecular clouds". Publications of the Astronomical Society of Japan, 3 de março de 2023. http://dx.doi.org/10.1093/pasj/psad006.
Texto completo da fonteResumo:
Abstract Hadronic γ-ray sources associated with supernova remnants (SNRs) can serve as stopwatches for the escape of cosmic rays from SNRs, which gradually develops from highest-energy particles to lowest-energy particles with time. In this work, we analyze the 13.7 yr Fermi-LAT data to investigate the γ-ray feature in/around the SNR G298.6−0.0 region. With γ-ray spatial analyses, we detect three point-like components. Among them, Src-NE is at the eastern SNR shell, and Src-NW is adjacent to the western edge of this SNR. Src-NE and Src-NW demonstrate spectral breaks at energies around/below 1.8 GeV, suggesting an old SNR age of >10 kyr. We also look into the X-ray emission from the G298.6−0.0 region, with the Chandra-ACIS data. We detected an extended keV source having a centrally filled structure inside the radio shell. The X-ray spectra are well fitted by a model which assumes a collisional ionization equilibrium of the thermal plasma, further supporting an old SNR age. Based on our analyses of the NANTEN CO- and ATCA-Parkes H i-line data, we determined a kinematic distance of ∼10.1 kpc from us to G298.6−0.0. This distance entails a large physical radius of the SNR of ∼15.5 pc, which is additional evidence for an old age of >10 kyr. Besides this, the CO data cube enables us to three-dimensionally locate the molecular clouds (MCs) which are potentially interacting with SNR G298.6−0.0 and could account for the hadronic γ-rays detected at Src-NE or Src-NW. Furthermore, the multiwavelength observational properties unanimously imply that the SNR–MC interaction occurs mainly in the north-eastern direction.
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Komitov, Boris, e Vladimir Kaftan. ""Danjon Effect", Solar-Triggered Volcanic Activity, and Relation to Climate Change". Russian Journal of Earth Sciences, 23 de dezembro de 2022, 1–12. http://dx.doi.org/10.2205/2022es000803.
Texto completo da fonteResumo:
The “Danjon effect” is a phenomenon that presents a tendency to concentrate the so-called “dark” total lunar eclipses (DTLE) near solar sunspot cycle minimum phases. It was a starting point for the present study, whose main subject is a statistical analysis of relationship between solar and volcanic activity for the maximum long time. To this end, the Smithsonian National Museum of Natural History's volcanic activity catalog was used. On its basis, a time series of the total annual volcanic eruptions for the period 1551–2020 AD has been built and explored for cycles of possible solar origin. Cycles with duration of 10–11, 19–25, ∼60, and ∼240 years (all with possible solar origin) has been established. It has also been found that there are two certain peaks of volcanic activity during the sunspot activity cycle: the first one is close to or after the sunspot minimum (sunspot cycle phase 0.9 ≤ Φ ≤1.0 and 0.1 ≤ Φ ≤ 0.2), and the second is wider – close to the sunspot cycle maximum (0.3 ≤ Φ ≤ 0.5). A third maximum is detected about 3–4 years after the sunspot cycle maximum (0.7 ≤ Φ ≤ 0.8) for the “moderate strong” volcanic eruptions with volcanic eruptive index VEI = 5. It corresponds to the geomagnetic activity secondary maximum, which usually occurs 3–4 years after the sunspot maximum. Φ is calculated separately on the basis of each sunspot cycle length. Finally, without any exclusions, all most powerful volcanic eruptions for which VEI ≥ 6 are centered near the ∼11-year Schwabe-Wolf cycle extremes. Trigger mechanisms of solar and geomagnetic activity over volcanic events, as well as their relation to climate change (in interaction with galactic cosmic rays (GCR) and/or solar energetic particles (SEP)), are discussed. The Pinatubo eruption in 1991 as an example of a “pure” strong solar–volcanism relationship has been analyzed in detail.