arXiv subjects

Alina Kochocki

Publications and source records attributed to Alina Kochocki.

5 recordsLinked to original sources

arXiv2026

An Evolving Leptonic Jet Model for Delayed Radio Flares in Neutrino Blazars

The jets of blazar active galactic nuclei (AGN) are promising sites of hadron acceleration and subsequent neutrino production, owing to their extreme intrinsic power and high radiation density. Potential associations of IceCube neutrinos with blazars displaying delayed radio flares, such as TXS~0506+056 and PKS~1424+240, may support this scenario. However, the mechanisms and location of particle acceleration in the jet remain unclear. The 2017 IceCube event associated with TXS 0506+056 was concurrent with the initial peak of a flare in gamma rays, followed by a longer flare at radio frequencies peaking three years later. State-of-the-art single-zone radiative source models focus on the compact high-energy-emitting region, and thus fail to describe this subsequent radio enhancement. In this work, we model the time-domain multi-frequency evolution of TXS 0506+056 by considering electron emission along the physically extended jet. We couple a numerical particle interaction framework with a dynamic description of the temporal and spatial jet evolution down to the parsec scale. We fit the model to multi-wavelength data, including multi-frequency radio light curves. The results suggest that the parsec-scale jet meets a population of older, cooled electrons near the edge of the observable radio core, establishing a causal relation between the initial high-energy emission and trailing radio activity. This spatially and temporally resolved modeling approach can offer new insights into the physical conditions along the jet of flaring neutrino candidate blazars.

astro-ph.HE↗

arXiv2026

Characterizing Gamma-Radio Delayed Flaring Activity from Blazars

Flaring activity from the jets of active galactic nuclei has been studied for several decades, closely related to the loading and evolution of the jet. In this work, we focus on the sub-hundred parsec jet region, well traced by non-thermal radio and gamma-ray emission. Only in recent years have light curves capturing the decade-long behavior of such sources become available for a large ensemble of objects. While previous studies have focused on a direct correlation or few-month lag between gamma-ray and radio activity, recent neutrino-bright blazars observed by the IceCube Neutrino Observatory present multi-year delays between initial gamma-ray activity and subsequent radio flares. In this work, we search for similar-timescale correlations between Fermi-LAT gamma-ray data and RATAN-600 radio data from ~100 blazars. We consider two gamma-ray bands, 100 MeV-1 GeV and 1 GeV-500 GeV, as well as the integral band, to compare correlations between potential opaque and unabsorbed regions of the jet. Gaussian process modeling is used for smooth light curve function prediction. We also analyze morphological AGN core data from the MOJAVE survey, forming a sub-selection to better illustrate potential dependence on location. In the broader selection, several sources exhibit delayed flares on the order of 1-3 years. In the stacked analysis, we find the highest correlation for a radio delay on the order of 180 days. The stacked correlation resulting from the MOJAVE sub-selection corresponds to a slightly smaller time lag. Delayed radio flares or extended radio emission appear to be notable features within the general blazar population.

astro-ph.HE↗

arXiv2026

Threshold Resource Redistribution in Spatially-Structured Kinship Networks

We present a model for a threshold-based resource redistribution process in a spatially-explicit population, characterizing the relation between kinship network structure, local interactions and persistence. We find that population survival becomes possible for lower resource densities, but leads to increased network heterogeneity and locally centralized clusters. We interpret this in relation to a feedback between the kinship network structure and reproduction ability. Agents receive stochastic resources and solicit additional resources from connected individuals when below a minimum, with each agent contributing a fraction of their excess based on relatedness. We first analyze a fully-connected population with uniform redistribution fraction and discuss mean field expectations as well as finite size corrections. We extend this model to a hub-and-spoke network, exploring the impact of network asymmetry or centrality on resource distribution. We then develop a spatially-limited population model with diffusion, local pairing, reproduction and mortality. Redistribution is introduced as a function of relatedness (generational distance through most-recent common ancestor) and distance. Redistribution-dependent populations exhibit a higher level of relational closeness with increased clustering for agents of highest node strength. These results highlight the interaction of resource density, cooperation and kinship in a spatially-limited regime.

q-bio.PE↗

arXiv2025

A Search for Astrophysical Neutrinos from Flaring X-ray Binaries with IceCube

Recently, IceCube has observed an excess of astrophysical neutrinos from the Galactic plane. Such a signal may indicate the presence of individual sources or a diffuse neutrino flux from the interactions of Galactic, hadronic cosmic rays. We consider the prospect of neutrino production in galactic X-ray binary systems. A model for neutrino production in the variable jets of these systems is discussed, and how such information may be incorporated within searches for astrophysical neutrinos from these sources. Two ongoing studies are presented on behalf of the IceCube Collaboration using 13 years of cascades and track-like events. In the first study, recently published model predictions are used to motivate the analysis of five selected black-hole X-ray binaries. Gamma-ray data from Fermi-LAT, as well as X-ray data from Swift/BAT and MAXI are used to search for temporal correlations between radiative cycles of the disk-jet system and potential neutrino emission. In the second study, a wider selection of variable X-ray binaries and their Swift/BAT light curves is considered and a stacking search is used to constrain the contribution of this source population to the Galactic neutrino flux.

astro-ph.HE↗

arXiv2021

Contribution of Secondary Neutrinos from Line-of-sight Cosmic Ray Interactions to the IceCube Diffuse Astrophysical Flux

In ten years of observations, the IceCube neutrino observatory has revealed a neutrino sky in tension with previous expectations for neutrino point source emissions. Astrophysical objects associated with hadronic processes might act as production sites for neutrinos, observed as point sources at Earth. Instead, a nearly isotropic flux of astrophysical neutrinos is observed up to PeV energies, prompting a reassessment of the assumed transport and production physics. This work applies a new physical explanation for neutrino production from populations of active galactic nuclei (AGN) and starburst galaxies to three years of public IceCube point source data. Specifically, cosmic rays (CRs) produced at such sources might interact with extragalactic background light and gas along the line of sight, generating a secondary neutrino flux. This model is tested alongside a number of typical flux weighting schemes, in all cases the all-sky flux contribution being constrained to percent levels of the reported IceCube diffuse astrophysical flux.

astro-ph.HE↗