Over the last decade, choked jets have attracted particular attention as potential sources of high-energy cosmic neutrinos. Testing this hypothesis is challenging because of the missing gamma-ray ...counterpart, hence the identification of other electromagnetic signatures is crucial. A choked-jet source is expected harboring in core-collapse supernovae with extended hydrogen envelopes, leading to the release of ultraviolet and optical emission for a few days. The ultraviolet band will be visible with an unprecedentedly large field of view by the future mission satellite ULTRASAT, for which we investigate the detection prospects in relation to the chocked source visibility in the optical band with the currently operating telescope ZTF. As these sources can produce neutrinos via hadronic and photohadronic interactions in choked jets, we also investigate how neutrino observations by existing Cherenkov high-energy neutrino telescopes (as IceCube and KM3NeT) can be used in association with electromagnetic signals coming from shock breakout events. By considering fiducial parameters of the source population and instruments performances, we estimate the maximum redshift up to which ULTRASAT and ZTF are able to detect ultraviolet and optical signals from these explosions, respectively. Furthermore, we discuss coordinated multi-messenger observations among those instruments and high-energy neutrino telescopes. ULTRASAT will be able to double the volume of sky currently visible by ZTF for the same emitting sources enlarging the sample of observed Type II supernovae by around 60%. For optimized multi-messenger detections, the delay between neutrino produced at the shock breakout occurrence (during the jet propagation inside the stellar envelope) and ULTRASAT observations should be of around 4(5) days, with a subsequent follow-up by instruments like ZTF about one week after.
The recently discovered TeV emission from Gamma-Ray Bursts (GRBs) hints towards a possible hadronic origin of this radiation component. We developed a Monte Carlo (MC) simulation reproducing the ...kinematics of photo-hadronic interactions at internal shocks, including the pair production process that the secondary gamma rays undergo in the GRB jet. We find that sub-TeV observations of GRB 190114C can be reproduced by a baryonic energy content comparable to that in sub-GeV photons and a bulk Lorentz factor \(\Gamma=100\), with a ms variability timescale. Neutrino flux predictions by the model are found to be consistent with experimental upper limits set by ANTARES and IceCube.
Neutrinos with energies ranging from GeV to sub-TeV are expected to be produced in Gamma-Ray Bursts (GRBs) as a result of the dissipation of the jet kinetic energy through nuclear collisions ...occurring around or below the photosphere, where the jet is still optically thick to high-energy radiation. So far, the neutrino emission from the inelastic collisional model in GRBs has been poorly investigated from the experimental point of view. In the present work, we discuss prospects for identifying neutrinos produced in such collisionally heated GRBs with the large volume neutrino telescopes KM3NeT and IceCube, including their low-energy extensions, KM3NeT/ORCA and DeepCore, respectively. To this aim, we evaluate the detection sensitivity for neutrinos from both individual and stacked GRBs, exploring bulk Lorentz factor values ranging from 100 to 600. As a result of our analysis, individual searches appear feasible only for extreme sources, characterized by gamma-ray fluence values at the level of F\(_{\gamma} \geq 10^{-2}\) erg cm\(^{-2}\). In turn, it is possible to detect a significant flux of neutrinos from a stacking sample of ~ 900 long GRBs (that could be detected by current gamma-ray satellites in about five years) already with DeepCore and KM3NeT/ORCA. The detection sensitivity increases with the inclusion of data from the high-energy telescopes, IceCube and KM3NeT/ARCA, respectively.
Due to their properties and applications, the growing demand for chitin and chitosan has stimulated the market to find more sustainable alternatives to the current commercial source (crustaceans). ...Bioconverter insects, such as Hermetia illucens, are the appropriate candidates, as chitin is a side stream of insect farms for feed applications. This is the first report on production and characterization of chitin and chitosan from different biomasses derived from H. illucens, valorizing the overproduced larvae in feed applications, the pupal exuviae and the dead adults. Pupal exuviae are the best biomass, both for chitin and chitosan yields and for their abundance and easy supply from insect farms. Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscope analysis revealed the similarity of insect-derived polymers to commercial ones in terms of purity and structural morphology, and therefore their suitability for industrial and biomedical applications. Its fibrillary nature makes H. illucens chitin suitable for producing fibrous manufacts after conversion to chitin nanofibrils, particularly adults-derived chitin, because of its high crystallinity. A great versatility emerged from the evaluation of the physicochemical properties of chitosan obtained from H. illucens, which presented a lower viscosity-average molecular weight and a high deacetylation degree, fostering its putative antimicrobial properties.
Basal sliding of glaciers and ice sheets remains a source of uncertainty in simulating the long‐term evolution of ice masses. In particular, the response of ice flow to changes in driving stress ...depends strongly on the value of the exponent m in nonlinear friction laws (e.g., Weertman's law), which is poorly constrained by observations. Here we constrain the friction law at a natural scale on Argentière Glacier (French Alps, hard‐bed), taking advantage of well‐resolved observations of glacier mass balance, geometry and basal sliding over time spans that include large changes in driving stress. By combining three different independent methods based on (a) surface velocity inversion, (b) transient length change modeling, and (c) direct local sliding measurements, we consistently find a value of m = 3.1 ± 0.3. We suggest that Weertman's law is suitable for modeling the long‐term evolution of hard‐bedded glaciers and ice sheets.
Plain Language Summary
Modeling the evolution of glaciers and ice sheets under climate variability requires accurate estimation of ice flow velocities by numerical models. One of the most challenging components of these models is the representation of basal sliding at the rock‐ice interface, generally described by relationships between stress and sliding speed. These relationships are mainly derived from laboratory experiments and theoretical studies, and their ability to represent nature still needs to be evaluated. Because direct observation beneath glaciers and ice sheets is difficult, few studies have attempted to validate sliding models from natural scale observations. In this context, our study provides a rare constraint, based on observations on an alpine glacier, on the law that should be used to model glacier sliding on clean bedrock (so‐called hard‐bed glaciers). We show that a simple power law performs well in explaining long‐term glacier behavior for a power exponent of ∼3.1. We suggest that this exponent should be adopted in non‐linear power laws incorporated into ice flow models that perform future projections of hard‐bedded glaciers and ice sheet evolution.
Key Points
We suggest that a Weertman friction law is suitable for multi‐decadal simulations of the hard‐bedded glaciers
Combining three independent methods and data sets we infer a Weertman's friction exponent of 3.1 ± 0.3
The temporal evolution of glacier fronts is found to be strongly sensitive to the friction law exponent
Reliable projections of ice sheets' future contributions to sea-level rise require models that are able to accurately simulate grounding-line dynamics, starting from initial states consistent with ...observations. Here, we simulate the centennial evolution of the Amundsen Sea Embayment in response to a prescribed perturbation in order to assess the sensitivity of mass loss projections to the chosen friction law, depending on the initialisation strategy. To this end, three different model states are constructed by inferring both the initial basal shear stress and viscosity fields with various relative weights. Then, starting from each of these model states, prognostic simulations are carried out using a Weertman, a Schoof and a Budd friction law, with different parameter values. Although the sensitivity of projections to the chosen friction law tends to decrease when more weight is put on viscosity during initialisation, it remains significant for the most physically acceptable of the constructed model states. Independently of the considered model state, the Weertman law systematically predicts the lowest mass losses. In addition, because of its particular dependence on effective pressure, the Budd friction law induces significantly different grounding-line retreat patterns than the other laws and predicts significantly higher mass losses.
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