We perform the first dedicated comparison of five hadronic codes (AM ^3 , ATHE ν A, B13, LeHa-Paris, and LeHaMoC) that have been extensively used in modeling the spectral energy distribution (SED) of jetted active galactic nuclei. The purpose of this comparison is to identify the sources of systematic errors (e.g., implementation method of proton–photon interactions) and to quantify the expected dispersion in numerical SED models computed with the five codes. The outputs from the codes are first tested in synchrotron self-Compton scenarios that are the simplest blazar emission models used in the literature. We then compare the injection rates and spectra of secondary particles produced in pure hadronic cases with monoenergetic and power-law protons interacting on blackbody and power-law photon fields. We finally compare the photon SEDs and the neutrino spectra for realistic proton-synchrotron and leptohadronic blazar models. We find that the codes are in excellent agreement with respect to the spectral shape of the photons and neutrinos. There is a remaining spread in the overall normalization that we quantify, at its maximum, at the level of ±40%. This value should be used as an additional, conservative, systematic uncertainty term when comparing numerical simulations and observations.

Blazars launch relativistic jets aligned with our line of sight, resulting in extreme beaming and making them among the most luminous extragalactic sources across the electromagnetic spectrum, from radio to $\gamma$-rays and potentially high-energy neutrinos. We present a comprehensive study of multimessenger emission from blazar jets powered by magnetic reconnection at varying distances from the supermassive black hole (SMBH). By generalizing previous models, we track the spatial evolution of key jet properties, including magnetization, bulk Lorentz factor, and external photon fields [accretion disc, broad-line region (BLR), dusty torus], and compute self-consistently the resulting broad-band photon spectra and neutrino emission. Our numerical simulations explore how the initial jet magnetization, particle acceleration efficiency, jet-to-accretion-power ratio, and accretion rate impact emission. We identify distinct regimes: synchrotron and synchrotron self-Compton dominate closer to the SMBH, where magnetization is high, while external Compton becomes significant near the BLR. Neutrino production is most efficient upstream of the BLR, driven by enhanced target photon densities and hard proton spectra. Our model predictions are then compared with observations of gamma-ray luminosities and synchrotron peak energies of Fermi-detected blazars, highlighting magnetic reconnection as a viable mechanism for electromagnetic and neutrino emissions in astrophysical jets. Crucially, our framework assumes equal injected luminosities of pairs and protons, thereby limiting baryon loading. While our model successfully reproduces the photon emission of extreme blazars such as 3HSP J095507.9 + 355101, it cannot self-consistently account for TXS-like flares, which would require extremely high baryon loading.

GRB 211211A is a long duration gamma-ray burst with a compact object merger origin. In this work, we model the time-resolved prompt-emission spectra of GRB 211211A within a leptonic radiation framework. Our goal is to infer the physical properties of the emitting region, study the temporal evolution of the radiating particle distribution, and make predictions for prompt emission at TeV energies. We perform Markov Chain Monte Carlo fitting of the time-resolved numerical spectral energy distribution (SED) models computed with the time-dependent non-thermal radiation code LeHaMoC. Our calculations include synchrotron emission and self-absorption, inverse Compton scattering including cooling in the Klein-Nishina regime, and photon-photon pair production. We find that the prompt emission of GRB 211211A between 10 keV and 10 MeV can be successfully reproduced by synchrotron radiation from a population of relativistic electrons. The spectral evolution during the first minute of the burst reflects different physical conditions in the emitting region. Our best-fit models favor fast-cooling solutions for the first 8 s, followed by a transition to slow-cooling solutions at later times. The accompanying synchrotron self-Compton emission extends to TeV energies, with predicted fluxes that would be detectable by CTAO for a burst similar to GRB 211211A, provided a sufficiently rapid response to a Fermi-GBM trigger or if the burst occurs within the CTAO field of view. The observed short variability of this burst requires very high Doppler factors (∼1000-2500) throughout the burst evolution. Such extreme Doppler factors are difficult to reconcile with the jet Lorentz factor inferred from afterglow modeling unless the prompt-emitting regions are themselves moving relativistically with respect to the jet plasma.

Rapid TeV flares have been observed from the core of the active galaxy M87. These have been attributed to inverse Compton scattering of disk photons by electrons and positrons accelerated in transient reconnection layers formed in baryon-poor regions of the magnetosphere of the central black hole, M87*. It has previously been shown that even a small number of protons accelerated in the same layers can lead to bright GeV proton-synchrotron flares, if protons receive greater than or similar to 20% of the dissipated power for reconnecting fields of similar to 100 G. We aim to investigate the role of Bethe-Heitler pair production in the emission of reconnection-driven flares from M87* in this physical regime. We perform numerical calculations that incorporate inelastic collisions between relativistic protons and photons, as well as photon-photon pair production, and compute the nonthermal radiation from the layer. The numerical calculations are also supported by analytical estimates. We find that disk photons act as targets for Bethe-Heitler pair production. The resulting pairs emit very high-energy synchrotron photons (greater than or similar to 0.1 TeV), which are subsequently attenuated by the disk photon field, leading to further pair production. The synchrotron emission of these secondary pairs produces soft photons, as part of an electromagnetic cascade, enhancing pion production and photon-photon attenuation down to tens of GeV energies.

The TeV neutrino signal observed by IceCube from the active galactic nucleus NGC 1068 can probe its innermost coronal regions. If these neutrinos originate from hadrons accelerated within a magnetized turbulent corona, their intensity and spectrum depend on the turbulent magnetic field strength and turbulence coherence scale. The gamma rays accompanying neutrino production are absorbed in this optically thick environment, in a way that depends sensitively on the size of the corona. By a joint fit of the IceCube and Fermi-LAT observations, we translate the multimessenger signal from NGC 1068 and the tentative signal from NGC 7469 into quantitative constraints on coronal properties. NGC 1068, with a significant TeV neutrino excess, favors a compact, strongly magnetized corona with a large turbulence coherence length relative to the coronal size. NGC 7469, with two similar to 100 TeV neutrino events, points instead to a somewhat larger corona with much smaller coherence length and high magnetization, but a very small fraction of energy in nonthermal protons. We obtain the diffuse flux from a population of Seyfert galaxies identical to either NGC 1068 or NGC 7469. Finally, we consider a third scenario, motivated by the spectral break observed in the diffuse neutrino flux at tens of TeV, with coronal properties intermediate between the two point-source-inspired models. To enable detailed comparisons with the IceCube and electromagnetic observations, we release our model predictions in a GitHub repository.

Turbulent coronae of supermassive black holes can accelerate nonthermal particles to high energies and produce observable radiation, but capturing this process is challenging due to comparable timescales of acceleration, cooling, and the development of cascades. We present a time-dependent numerical framework that self-consistently couples proton acceleration-modeled by the Fokker-Planck equation-with leptonic-hadronic radiation. For the neutrino-emitting Seyfert galaxy NGC 1068, we reproduce the neutrino spectrum observed by IceCube while satisfying gamma-ray constraints. We also consider a transient corona scenario, potentially emerging in tidal disruption events like AT 2019dsg, and show that cascade feedback on proton cooling can impact proton acceleration and radiation processes in weaker coronae, producing delayed optical or ultraviolet, x-ray, and neutrino emissions of O(100 d). This flexible tool efficiently models multimessenger signals from both steady and transient astrophysical sources, providing insights in combining particle acceleration and radiation mechanisms.

Blazars are characterized by relativistic jets that are closely aligned with our line of sight. This results in relativistic beaming, making blazars among the most luminous extragalactic sources across the electromagnetic spectrum, from radio waves to gamma-rays and, potentially, in high-energy neutrinos. We present a comprehensive study of multi-messenger emission from blazar jets powered by magnetic reconnection occurring at varying distances from the supermassive black hole (SMBH). By generalizing previous models, we explore how the emission characteristics depend self-consistently on the spatial evolution of key jet properties, including magnetization, bulk Lorentz factor, and external photon fields (accretion disc, broad-line region, and dusty torus). Using numerical simulations, we examined the impact of the initial jet magnetization, particle acceleration efficiency, jet-to-accretion power ratio, and mass accretion rate on the broadband photon spectra and neutrino emission. Our findings reveal distinct emission regimes characterized by different dominant radiative processes: synchrotron and synchrotron self-Compton dominate closer to the SMBH where magnetization is high, while external Compton (EC) processes become significant near the broad-line region (BLR). Neutrino production efficiency is highest upstream of the BLR, driven by enhanced photon target densities from synchrotron and external photons available for photopion interactions, whereas the proton particle distribution is hard. Our model predictions are compared with observations of gamma-ray luminosities and synchrotron peak energies of Fermi-detected blazars, highlighting magnetic reconnection as a potential mechanism driving both electromagnetic and neutrino emissions in astrophysical jets.

Active galactic nuclei (AGN) can accelerate protons to energies of ∼10-100 TeV, with secondary production of high-energy neutrinos. If the acceleration is driven by magnetized turbulence, the main properties of the resulting proton and neutrino spectra can be deduced based on insights from particle-in-cell simulations of magnetized turbulence. We have previously shown that these properties are consistent with the TeV neutrino signal observed from the nearby active galaxy NGC 1068. In this work, we extend this result to a population study. We show that the produced neutrino flux depends mainly on the energetics of the corona - the relative fraction of X-ray, magnetic, and non-thermal proton energy - and on the spectral energy distribution of the AGN. We find that coronae with similar properties can explain neutrinos from the candidate AGN for which IceCube has reported an excess, albeit less significant than NGC 1068. Building on this framework, we show how the neutrino signal evolves with the AGN luminosity, and use this AGN sequence to predict the diffuse neutrino flux from the extragalactic population, showing that it can account for the diffuse neutrino signal observed by IceCube in the ∼1-100 TeV energy range.

High-energy gamma rays can trigger electromagnetic cascades via pair production on ambient photons, reprocessing their energy to lower frequencies. A classic example is the cascade from the gamma rays produced by ultra-high-energy cosmic rays in extragalactic photon fields, whose universal spectral shape was first described by Berezinsky in the 1970s. Recently, internal cascades, developing within the gamma-ray sources themselves, have gained a prominent role, as the IceCube data suggest that most detected neutrinos originate in gamma-ray-opaque environments. We analyze under what conditions these internal cascades can approach a universal spectrum. Since the Berezinsky treatment breaks down if synchrotron losses dominate, we present a generalized theory incorporating synchrotron-dominated cascades. We show the emergence of universal cascade spectrum among various examples of high-energy sources containing non-thermal cosmic rays, and discuss the conditions for its appearance.

Super-Eddington accretion onto stellar-mass compact objects powers fast outflows in ultra-luminous X-ray sources (ULXs). Such outflows, which can reach mildly relativistic velocities, are often observed forming bubble structures. Wind bubbles are expected to develop strong wind termination shocks, which are sites of great interest for diffusive shock acceleration. We developed a model of diffusive shock acceleration in the wind bubbles powered by ULXs. We find that the maximum energy in these objects can easily reach the PeV range, promoting winds from ULXs as a new class of PeVatrons. We specialized our model in the context of the Galactic source SS 433 and show that high-energy protons in the bubble might explain the highest energy photons ($>100$ TeV) and their morphology recently observed by LHAASO. In this paper, we discuss the detectability of such a source in neutrinos, and we analyze the possible radio counterpart of ULXs focusing on the case of W50, the nebula surrounding SS 433. Finally, we discuss the possible contribution of Galactic ULXs to the cosmic-ray flux at the knee, concluding that their role could be significant only if one of these sources, currently undetected, were sufficiently close.

OBJECTIVES:To evaluate the influence of bias from methodological characteristics on intervention effect estimates in nutrition randomized controlled trials (RCTs) using the Cochrane Risk Of Bias 2 (RoB2) tool. METHODS:RCTs published until 2020 were selected from a representative sample of 183 nutrition meta-analyses. Pairs of reviewers conducted data extraction and risk of bias (RoB) assessments. Average estimates due to bias (ratio of risk ratio [RRR]) were computed through meta-analyses using a random-effects model, comparing RCTs rated as "high risk" or "some concerns" to those rated as "low risk" of bias. Subgroup analyses explored differences across RoB domains, types of interventions, and outcomes. Heterogeneity was assessed through I2 and τˆ2, and prediction intervals were calculated. RESULTS:We included 26 meta-analyses, encompassing 82 RCTs with 120 outcome-specific RoB assessments. Of these, 70% were rated as "some concerns", 18.3% as "low risk", and 11.7% as "high risk" of bias. Overall RoB did not affect intervention effect estimates (RRR 0.99, 95% CI 0.85-1.14; I2 = 36%; heterogeneity estimator [τˆ2] = 0.03; prediction interval [PI] 0.66-1.47). Most RoB domains did not reveal differences in effect estimates, except for trials with biases related to deviations from the intended intervention (RRR 1.29, 95% CI 1.13-1.48; I2 = 2%; τˆ2 = 0.01; PI 0.97-1.72). We confirmed these findings in subgroup and meta-regression analyses. CONCLUSION:Most methodological characteristics in nutrition RCTs, as assessed by RoB2, did not overestimate or underestimate intervention effect estimates. However, the unexpected finding that biases arising from deviations from intended interventions may lead to an underestimation of effects, rather than an overestimation, requires further research. PLAIN LANGUAGE SUMMARY:RCTs are considered the most reliable method for determining whether an intervention is effective. However, weaknesses in study design or conduct can distort the results, a problem known as bias. The RoB2 tool helps researchers check in a structured way whether bias is present and how much it might affect the results. In this study, we looked at 82 RCTs on dietary interventions published up to 2020. We assessed 120 outcome-specific RoB assessments and identified whether they had a low, some concerns, or high RoB. We then compared the results of trials with a higher RoB to those with a low RoB to see whether bias influenced the reported treatment effects. The reviewed trials showed variable levels of RoB and had little overall impact on the trial results. The main exception was how well participants followed the assigned diet and whether the researchers used the best available analysis methods. Problems in this area may have made the intervention's true effect seem smaller than it really was. Our findings suggest that studies on nutrition interventions are mostly free from major bias and their results can be considered reliable. However, how well participants followed the assigned intervention and how good the analysis methods were seemed to play an important role. More research is needed to understand how study quality influences the results of nutrition trials.

A ubiquitous feature of accreting black hole systems is their hard X-ray emission which is thought to be produced through Comptonization of soft photons by electrons and positrons in the vicinity of the black hole, in a region with optical depth of order unity. The origin and composition of this Comptonizing region, known as the corona, is a matter open for debate. In this paper we investigate the role of relativistic protons accelerated in black-hole magnetospheric current sheets for the pair enrichment and neutrino emission of AGN coronae. Our model has two free parameters, namely the proton plasma magnetization σ_ p, which controls the peak energy of the neutrino spectrum, and the Eddington ratio λ_ X, Edd (defined as the ratio between X-ray luminosity L_ X and Eddington luminosity L_ Edd), which controls the amount of energy transferred to secondary particles. For sources with λ_ X, Edd≳ λ_ Edd, crit (where λ_ Edd, crit∼ 10^-1 for σ_ p=10^5 or ∼ 10^-2 for σ_ p=10^7), proton-photon interactions and γγ annihilation produce enough secondary pairs to achieve Thomson optical depths τ_ T∼ 0.1-10. In the opposite case of λ_ X, Edd≲ λ_ Edd, crit, the coronal pairs cannot originate only from hadronic interactions. Additionally, we find that the neutrino luminosity scales as L^2_ X/L_ Edd for λ_ X, Edd≲ λ_ Edd, crit, while it is proportional to L_ X for higher λ_ X, Edd values. We apply our model to four Seyfert galaxies, including NGC 1068, and discuss our results in light of recent IceCube observations.

Anorexia nervosa (AN) is a severe eating disorder. With a lifetime prevalence of 1.4

The blazar TXS 0506+056 has been the first astrophysical source associated with high-energy astrophysical neutrinos, and it has emerged as the second-most-prominent hotspot in the neutrino sky over 10 yr of observations. Although neutrino production in blazars has traditionally been attributed to processes in the powerful relativistic jet, the observation of a significant neutrino flux from NGC 1068—presumably coming from the active galactic nucleus (AGN) corona—suggests that neutrinos can also be produced in the cores of AGN. This raises the question whether neutrino production in TXS 0506+056 is also associated with the core region. We study this scenario, focusing on the hypothesis that this blazar is a masquerading BL Lac object, a high-excitation quasar with hidden broad emission lines and a standard accretion disk. We show that magnetic reconnection is an acceleration process necessary to reach tens of PeV proton energies, and we use observationally motivated estimates of the X-ray luminosity of the coronal region to predict the emission of secondaries and compare them to the observed multiwavelength and neutrino spectra of the source. We find that the coronal neutrino emission from TXS 0506+056 is too low to describe the IceCube observed neutrinos from this AGN, which in turn suggests that the blazar jet remains the preferred location for neutrino production.

Non-jetted AGN exhibit hard X-ray emission with a power law spectrum above ∼2 keV, which is thought to be produced through Comptonization of soft photons by electrons and positrons (pairs) in the vicinity of the black hole. The origin and composition of this plasma source, known as the corona, is a matter open for debate. Our study focuses on the role of relativistic protons accelerated in black-hole magnetospheric current sheets in the neutrino production of AGN coronae. We present a model that has two free parameters, namely the proton plasma magnetization σ_ p, which controls the peak energy of the neutrino spectrum, and the Eddington ratio λ_ Edd (defined as the ratio between X-ray luminosity L_ X and Eddington luminosity L_ Edd), which controls the amount of energy transferred to secondary particles. Furthermore, we combine our coronal model with an AGN population in order to provide a prediction for the diffuse neutrino flux measured on Earth. We compare our results with the observational data by IceCube and we find a satisfactory agreement on both the flux value and the slope of the neutrino distribution when we assume a σ_ p value of 10^5 for all the sources in our sample.

The AXIS Community Science Book represents the collective effort of 592 scientists worldwide to define the transformative science enabled by the Advanced X-ray Imaging Satellite (AXIS), a next-generation X-ray mission selected by NASA's Astrophysics Probe Program for Phase A study. AXIS will advance the legacy of high-angular-resolution X-ray astronomy with 1.5” imaging over a wide 24' field of view and an order of magnitude greater collecting area than Chandra in the 0.3-12 keV band. Combining sharp imaging, high throughput, and rapid response capabilities, AXIS will open new windows on virtually every aspect of modern astrophysics, exploring the birth and growth of supermassive black holes, the feedback processes that shape galaxies, the life cycles of stars and exoplanet environments, and the nature of compact stellar remnants, supernova remnants, and explosive transients. This book compiles 138 community-contributed science cases developed by five Science Working Groups focused on AGN and supermassive black holes, galaxy evolution and feedback, compact objects and supernova remnants, stellar physics and exoplanets, and time-domain and multi-messenger astrophysics. Together, these studies establish the scientific foundation for next-generation X-ray exploration in the 2030s and highlight strong synergies with facilities of the 2030s, such as JWST, Roman, Rubin/LSST, SKA, ALMA, ngVLA, and next-generation gravitational-wave and neutrino networks.

Active galactic nuclei (AGN) can accelerate protons to energies of ∼10–100 TeV, with secondary production of high-energy neutrinos. If the acceleration is driven by magnetized turbulence, the main properties of the resulting proton and neutrino spectra can be deduced based on insights from particle-in-cell simulations of magnetized turbulence. We have previously shown that these properties are consistent with the TeV neutrino signal observed from the nearby active galaxy NGC 1068. In this work, we extend this result to a population study. We show that the produced neutrino flux depends mainly on the energetics of the corona—the relative fractions of X-ray, magnetic, and nonthermal proton energy—and on the spectral energy distribution of the AGN. We find that coronae with similar properties can explain neutrinos from the candidate AGN for which IceCube has reported an excess, albeit less significant than NGC 1068. Building on this framework, we show how the neutrino signal evolves with AGN luminosity, and use this AGN sequence to predict the diffuse neutrino flux from the extragalactic population, showing that it can account for the diffuse neutrino signal observed by IceCube in the ∼1–100 TeV energy range.