Journées de l'AT-PEM 2026 - Défis numériques en astrophysique des hautes énergies

Session

Invited talks

S5

18 nov. 2026, 14:45

Amphithéâtre Charpak (Sorbonne Université, campus Jussieu)

3. Diffuse Galactic gamma-ray emission at very high energies, and TeV halos around pulsars

Gwenael GIACINTI (APC Paris)

18/11/2026 14:45

Gamma-ray observations provide important information on cosmic-ray (CR) propagation in our Galaxy.First, we present a new model of CR propagation in the Milky Way, where CRs are injected at discrete transient sources in the disc. We then calculate the corresponding diffuse Galactic gamma-ray emission. We find that the diffuse gamma-ray emission above 100 TeV is very clumpy, and does not...

4. Astrophysical gravitational-wave backgrounds

Irina Dvorkin (Institut d'Astrophysique de Paris)

18/11/2026 15:05

The detection of gravitational waves from compact-binary coalescences by LIGO–Virgo–KAGRA has opened a new window onto the Universe. As detector sensitivities improve, and with the advent of future observatories such as LISA and the Einstein Telescope, the number and diversity of individually detectable gravitational-wave sources will increase dramatically. Yet many more sources will remain...

5. Field line & particle transport in magnetic turbulence : synthetic vs MHD

Yoann GÉNOLINI (LAPTh, Annecy)

18/11/2026 15:25

Over the past decade, a wealth of new data has ushered in an era of precision cosmic-ray physics. By revealing previously unanticipated features in cosmic-ray spectra, these observations challenge current paradigms of Galactic cosmic-ray acceleration and transport. When it comes to modeling cosmic-ray transport in magnetic turbulence, existing theoretical models still struggle to accurately...

13. The impact of pair production on Gamma Ray Burst prompt emission spectra

Mouad Gnaoui (IAP, Sorbonne Université)

19/11/2026 09:45

Gamma Ray Burst prompt emission is widely attributed to radiation from accelerated electrons within ultra-relativistic ejecta. The detection of high energy components in several GRBs, along with the theoretical predictions of inverse Compton scattering, suggest the presence of abundant photons above the pair production threshold in the comoving frame. Under such conditions, photon-photon...

14. Multi-messenger modeling of binary neutron star mergers

Sofia Bisero (GEPI, Observatoire de Paris, Université PSL, CNRS)

19/11/2026 10:05

I will discuss the key ingredients required to model the multi-messenger emission from binary neutron star mergers, from gravitational waves to electromagnetic radiation, highlighting the main degeneracies and open questions. I will then move from individual events to populations, describing how synthetic populations can be constructed, from astrophysical assumptions to observational predictions.

15. From numerical simulations to Bayesian inference: surrogate models for time-resolved blazar SEDs

Damien BEGUE (APC)

19/11/2026 10:25

Time-resolved spectral energy distributions (SEDs) provide a powerful probe of the physical evolution of highenergy sources, but extacting this information with detailed numerical models is computationally challenging. This becomes particularly prohibitive when full posterior sampling is required. To address this challenge, we developed a surrogate-modeling framework, based on convolutional...

25. Neutrino flavor instabilities: from theory to observables

Julien Froustey (IFIC, Universitat de València)

19/11/2026 15:15

Accurately modeling neutrino flavor oscillations in global simulations of core-collapse supernovae remains a major challenge, albeit a potentially crucial one for making reliable predictions. Indeed, it is now widely recognized that flavor instabilities, in which neutrino distributions computed in classical transport frameworks can be dramatically reshaped by flavor conversion, are ubiquitous...

26. Cosmic-ray transport from large to small scales

Phan Vo Hong Minh (LUX)

19/11/2026 15:35

I will present current progress on Galactic cosmic-ray transport with a strong focus on the escape of cosmic rays around supernova remnants studied using particle-in-cell simulations. Some results concerning the transport of cosmic rays in their self-generated turbulence will be discussed together with potential observational consequences.

27. Particle acceleration in novae

Vincent Tatischeff (IJCLab)

19/11/2026 15:55

Classical and recurrent novae are powered by thermonuclear runaways on the surfaces of accreting white dwarfs. Novae have emerged as an important class of astrophysical particle accelerators, as demonstrated in particular by the discovery of GeV gamma-ray emission with Fermi-LAT. In classical novae, particle acceleration is thought to occur primarily at internal shocks within the ejecta, which...

36. The Growth of Supermassive Black Holes with Cosmological Hydrodynamical Simulations

Dr Yohan Dubois (Institut d'Astrophysique de Paris)

20/11/2026 09:45

Cosmological hydrodynamical simulations are a powerful tool for modelling the complexity of galaxy formation, along with the supermassive black holes (SMBHs) at their centres. I will begin by reviewing how modern simulations model SMBH growth, including gas accretion, active galactic nucleus feedback, and black hole mergers. I will then present the resulting predicted SMBH populations and show...

37. Black Hole Accretion: Simulating Electromagnetic Observables

Irene Urso (LIRA, Paris Observatory)

20/11/2026 10:05

Three computational steps are required to construct synthetic electromagnetic observations of black hole accretion flows, specifically source modelling, general relativistic ray tracing, and general relativistic radiative transfer (GRRT). In this talk, we review various existing approaches, highlighting their respective advantages and limitations. For source modelling, we discuss...

38. Turbulence in extreme environments

Martin Lemoine (APC (Astroparticule & Cosmologie, CNRS - Université de Paris))

20/11/2026 10:25

This talk will review some recent progress in numerical modelling of turbulence in extreme environments, its relevance for energy dissipation, particle tranport, and acceleration, and its connections to high-energy multimessenger astrophysics.

48. Population synthesis of pulsars and magnetars

Mattéo Sautron (ObAS)

20/11/2026 15:00

Population synthesis is a powerful numerical tool that allows one to infer the parameters characterizing a given population.
Within this framework, pulsars and magnetars are generated at birth and their evolution is followed up to the present epoch.
Once this evolution is modeled, detection criteria are applied in order to determine whether each object in the simulated population would be...

49. A kinetic plasma perspective on black hole magnetospheres

Enzo Figueiredo (IPAG, CNRS, Université Grenoble Alpes)

20/11/2026 15:20

Recent high-angular-resolution observations of black holes have revealed magnetospheric structures in their immediate vicinity, which may drive active galactic nuclei jets and particle acceleration. Fundamental questions persist regarding jet launching and the variability of electromagnetic emission. In this talk, I present how general relativistic kinetic plasma simulations have transformed...

50. Fast radio bursts as precursor radio emission from monster shocks

Arno Vanthieghem (Observatoire de Paris)

20/11/2026 15:40

Fast radio bursts (FRBs) are among the most luminous coherent transients in the Universe, yet the physical mechanisms responsible for their emission remain poorly understood. In this talk, I will explore the kinetic physics underlying a theoretical scenario in which low-frequency fast magnetosonic waves, launched by magnetar activity, steepen as they propagate through the declining background...