Gammapy is an open-source Python framework for gamma-ray astronomy. Built on the scientific Python ecosystem and using community-supported open data standards, it provides a unified platform for data reduction and modeling across a wide range of high-energy instruments, enabling interoperability between observatories and supports comprehensive joint analyses. Since its start in 2014 as a...
Blazars are among the most powerful objects in the Universe and are prime candidates for producing ultra-high-energy cosmic rays and astrophysical neutrinos. In today’s multi-messenger era, combining data from different cosmic messengers with advanced modeling tools is key to unlocking the secrets of these extreme sources.
In this contribution, we present a novel, user-friendly...
In April 2013, the TeV blazar Mrk421 underwent one of its most powerful emission outbursts to date. An extensive multi-instrument campaign, which included MAGIC, VERITAS, and NuSTAR, provided comprehensive VHE and X-ray coverage over nine consecutive days.
In this talk I will present a detailed spectral analysis of the X-ray and VHE emissions on sub-hour timescales throughout the flare. We...
The role of active galactic nuclei in the production of high-energy neutrinos is crucial in the understanding of the excess of neutrinos seen by the IceCube observatory in the direction of the blazar TXS 0506+056 and the Seyfert galaxy NGC 1068. In particular blazars jets are potential sites of cosmic-ray acceleration, where neutrino production would be naturally explained along with the...
We present updates to the stationary lepto-hadronic code from Boettcher et al. (2013) (B13). We demonstrate the implementation of the semi-analytical Bethe-Heitler pair production calculation from Karavola & Petropoulou (2024).
B13 has also been implemented in Gammapy,as a callable model, enabling precise modelling of multi-wavelength data following Nievas Rosillo et al. (2025)....
There have been recent population studies supporting the idea that radio-loud blazars can be the potential source of high-energy astrophysical neutrinos being observed by IceCube. The understanding of neutrino production from these sources is intimately connected to explaining their multi-wavelength spectra as well. In this talk, ongoing work will be presented in modelling the lepto-hadronic...
TXS 0506+056 is the first blazar associated with a high-energy neutrino detection (IceCube-170922A) in 2017. Notably, no immediate radio brightening accompanied this neutrino producing γ-ray flare but instead, a major radio outburst occurred about 2.5 years later. We investigate whether the 2017 flare accompanied by a high-energy neutrino event can lead to such a delayed radio flare. Using...
In September 2017, a high-energy neutrino event detected by the IceCube Neutrino Observatory (IceCube-170922A) was associated, at the $3\sigma$ level, with a gamma-ray flare from the blazar TXS 0506+056. Cosmic rays that are accelerated in astrophysical sources can escape from their jets and interact with background radiation fields. Interactions with the extragalactic background light can...
Identifying the astrophysical sources of high-energy cosmic neutrinos remains a central challenge in multi-messenger astronomy. Following the association of a 290 TeV neutrino detected by IceCube with the flaring blazar TXS 0506+056, theoretical studies have focused on modelling the photon–neutrino connection in blazars. We present a computational framework combining advanced...
The origin of Very High-Energy (VHE) gamma-ray emission in High-frequency peaked BL Lac objects (HBLs) remains debated. While standard leptonic models successfully explain the synchrotron peak, they often struggle to reproduce hard TeV spectra without extreme parameters. We explore a hybrid scenario where the VHE emission arises from the interaction of stochastically accelerated protons with...
Active Galactic Nuclei (AGN) and their relativistic jets that emit radiation covering almost the entire electromagnetic spectrum, have been few of the most fascinating subjects in astronomy for decades, yet the composition of these relativistic jets is still not clearly known. The origin of the high energy peak in the Spectral Energy Distribution (SED) of blazars has been an open question in...
The origin of high-energy neutrinos is fundamental to our understanding of the Universe. Immense effort has been put into identifying extragalactic sources of TeV-PeV neutrinos but still to no avail. Blazars has been proposed as one of the most promising candidates, however, the original association of a blazar with a high-energy neutrino has generated more questions than answers. I will...
The Seyfert galaxies NGC 1068 and NGC 4151 have emerged as the most promising counterparts of 4.2σ and 3.0σ neutrino excesses detected by IceCube in the TeV energy range.
Gamma rays and neutrinos are co-produced at the same flux level via hadronic interactions between the parent proton population and the ambient matter and radiation in the neutrino-emitting region. Observations of NGC 1068...
Non-jetted AGN exhibit hard X-ray emission with a power law spectrum above $\sim$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 this presentation, I will show a (brief) update regarding the new capabilities of the OneHaLe (one-zone hadro-leptonic) code including some applications. New features include full hdf5 compatibility (output is written to a single file), easier handling of the injection particle distrbution as well as the variability input, and others. The easier handling allows the user to have direct...
The super-fast (~day), very-high-energy (VHE; >0.1 TeV) photon flares from the nearby active galactic nucleus M87 provide a unique, exciting opportunity to fast-forward our understanding of particle acceleration in jets. After a long break since 2010, the Event Horizon Telescope (EHT) multiwavelength (MWL) campaign captured a new VHE flare in 2018 with unprecedented frequency coverage...
I am going to discuss recent advancements in AGNpy, a Python library designed for modeling radiative processes in Active Galactic Nuclei (AGNs). I will focus on the new code dedicated to the time-dependent modelling of AGN processes, which can be used for searching for LIV signatures in AGN radiation. I will also cover other changes added recently to the code, and explain the plans for further...
Looking to the future of multi-messenger astrophysics, it is still unclear what we can expect, but phenomena that are difficult to observe now will likely become
relevant and significant. These certainly include the coalescence of compact objects such as neutron star binaries and black hole-neutron star pairs.
Although the gravitational waves produced by these events have only been detected...
Turbulent particle acceleration is widely invoked to explain high-energy emission from extreme astrophysical sources. However, standard second-order Fermi models based on Fokker–Planck equation neglect complex non-linear effects emerging in the high-amplitude ($\delta B/B \sim 1$) and relativistic turbulence regimes, expected in many astrophysical environments. Recent MHD and PIC simulations...
Stochastic particle acceleration in magnetized turbulent plasmas, and its resulting multi-messenger signatures, has received increased attention in recent years. A detailed modeling of this process is however made complex by the need to treat simultaneously particle acceleration and radiative processes.
We present here a hybrid numerical code that couples AM3 [1], a state-of-the-art,...
Turbulent coronae around supermassive black holes can accelerate non-thermal particles to high energies and power observable emission, but the comparable timescales of acceleration, cooling, and electromagnetic cascades make this process hard to capture. In this seminar, I will introduce a time-dependent framework that self-consistently couples proton acceleration—modeled with the...
High center-of-mass electromagnetic (EM) interactions could produce decaying heavy leptons and hadrons, leading to neutrino generation. These processes might occur in the most extreme astrophysical and cosmological scenarios, potentially altering the expected gamma-ray and neutrino fluxes in both the hadronic and the leptonic pictures. For instance, neutrinos could arise from high-redshift EM...
The DIPLODOCUS (Distribution-In-PLateaux methODOlogy for the Computation of transport eqUationS) framework, and its associated code Diplodocus.jl, for anisotropic particle transport and emission modelling of astrophysical sources (focused on jets), are now publicly available.
In this contribution, we will update the community on the project’s status, development and direction, and provide...
Supernova remnants are considered major contributors to the Galactic cosmic-ray population. However, many existing numerical models of particle acceleration at the remnants shocks still rely on over-simplified geometries that cannot reproduce the rich and asymmetric emission morphologies that many remnants show on account of their interaction with their inhomogeneous surroundings.
In this...
Constraining neutron-star structure requires models that are physically faithful yet fast enough for the evaluations required by Bayesian sampling. We begin with static vacuum field (SVF) magnetospheres, where direct light-curve synthesis is too slow for practical MCMC; our neural-network (NN) surrogate matches SVF profiles with high fidelity and provides ~400x speedups, enabling multipolar...
Neutron stars—pulsars—and their magnetospheres are key sources for multi-messenger astrophysics. Their emission spans the entire electromagnetic spectrum, they are strong candidates for contributing to the cosmic-ray positron excess, and theoretical models (though not yet confirmed observationally) suggest that they may also produce high-energy neutrinos in the TeV–PeV range. By combining...
We will present our efforts to obtain the reference solution for the ideal force-free 3D pulsar magnetosphere with Physics Inspired Neural Networks (PINNs). We will present our first results, we will show where and why they differ from all current state-of-the-art solutions, and we will discuss the potential of PINNs for astrophysics.
Comprehensive analysis of time-resolved spectral energy distributions (SEDs) of blazars is essential for understanding their underlying physical processes. However, when numerical kinetic models are combined with rigorous statistical inference-such as full posterior sampling instead of local optimization-the task of fitting large numbers of SEDs becomes computationally prohibitive. To address...
We present a convolutional neural network (CNN) surrogate model designed to reproduce the time-dependent synchrotron spectra of GRB prompt emission. The training set consists of physically motivated simulations in which a single electron-injection episode and a decaying magnetic field generate the evolving spectra of FRED-shaped pulses. The CNN maps the physical parameters to the full...
Astrophysics is entering a data-rich era driven by multi-wavelength observatories and multi-messenger experiments. These facilities produce vast, heterogeneous datasets that challenge traditional analysis pipelines. General-purpose AI systems, while powerful, often lack the contextual reasoning and scientific rigor required for astrophysical interpretation. AstroGenesis is an AI-powered,...
Modeling the spectral energy distributions (SEDs) of blazars with physically motivated models is computationally expensive, as it requires solving coupled differential equations numerically and scanning high-dimensional parameter spaces.
In this contribution I will present our recent application of machine learning to accelerate the evaluations of blazar SED. Our method relies on a neural...
The macroscopic structure and dynamics of relativistic AGN jets regulate where and how particles reach very high energies. Recollimation shocks—and the turbulent regions that form downstream—act as natural sites of localized dissipation and non-thermal particle acceleration. Using high-resolution 2D and 3D RMHD simulations with PLUTO, we examine how external confinement, jet–ambient pressure...
With the open-source software AM³, particle interactions and radiative emission in astrophysical objects like blazars can be simulated assuming a homogeneous and isotropic magnetic field. However, the synchrotron radiation from blazars is known to be polarized. Time-dependent multi-wavelength polarization measurements reveal magnetic field structures and shed light into the radiative processes...
Multiwavelength polarimetric studies provide a powerful tool to probe the structure and physics of blazar jets, and in particular high-energy polarisation measurements allow us to discriminate between competing models for their multimessenger emission. A new generation of X-ray and gamma-ray polarimeters is currently under development to achieve that. In this work, we investigate the...
High energy (HE) neutrinos have been observed by neutrino observatories for over a decade. Nevertheless, their origin and mechanisms responsible for their production still remain a mystery. Tidal disruption events (TDEs) have been proposed as candidate HE neutrino emitters, however a statistical association between the two has yet to be established. I will discuss results from the statistical...
Relativistic jets from black hole X-ray binaries (BHXBs) and active galactic nuclei (AGN) are powerful accelerators of cosmic rays (CRs), reaching energies up to the PeV scale and shaping the multiwavelength (MW) and multimessenger sky. Recent observations – including TeV detections of BHXBs and refined AGN spectra – motivate unified modeling frameworks capable of capturing jet physics across...
Sagittarius A* has been investigated for years and is one of the most interesting sources in the Galactic Center, a region enriched by strong magnetic fields, dense gas and enhanced cosmic-ray activity. The black hole’s shadow was imaged for the very first time in 2022 by the Event Horizon Telescope at a frequency of 230 GHz, demonstrating a characteristic ring morphology and a significantly...
General Relativistic MagnetoHydroDynamic (GRMHD) simulations solve the time-dependent electro- and hydrodynamic partial differential equations in arbitrary spacetimes. They usually employ conservative integration routines to advance the solution in the time domain, which are known to produce mostly numerically stable results. The most common one is the Finite Volume Method, which accurately...
The first multimessenger observation involving gravitational waves, GW170817, demonstrated the essential role of combining information from different messengers and from the entire electromagnetic spectrum to achieve a comprehensive understanding of astrophysical phenomena. In the coming years, the Cherenkov Telescope Array Observatory (CTAO) — the largest and most sensitive ground-based...
