Schedule

1st Meeting in Bern, December 9-12, 2019

Monday Dec. 9: Overview of high-energy observations and particle acceleration mechanisms

Present and future observations of broadband high-energy emission (X-rays to VHE gamma-rays) from pulsars. What we can learn from them. What is important and what is not. Are there any systematics that could guide the models. What we believe is their origin in the three most studied pulsars, Crab, Vela and Geminga, in young pulsars, and in millisecond pulsars. Acceleration mechanisms. Unresolved issues.

Kazanas: Welcome. Scope of meeting. General issues: pair formation, particle acceleration, analogy with AGN

Smith: Gamma-ray pulsars with Fermi and their radio polarization

Grenier: Gamma-ray pulsars: luminosity, spectral distributions, and variability (remotely)

Lyutikov: Spectra and emission mechanisms of gamma-ray pulsars (remotely)

Each review presentation + discussion: 1 ½ hours


Tuesday Dec. 10: Overview of magnetospheric modeling

Different modeling approaches with emphasis on high-energy production. What have we learned from them. Approximations.

Harding: Broadband high-energy emission in pulsars

Cerutti: Review of Particle-in-Cell Simulations (remotely)

Philippov: Global PIC models of magnetospheres and consequences for modeling high-energy and radio emission (remotely)

Spitkovsky: Reconnection and radiation in the outer magnetosphere

Each review presentation + discussion: 1 ½ hours


Tuesday Dec. 10, 7 p.m.: Dinner, Restaurant Beaulieu


Wednesday Dec. 11: Model comparison and evaluation

Different modeling approaches with emphasis on high-energy production (continued)

Contopoulos: Hybrid modeling of pulsar magnetospheres: a personal view

Petri: Spectral/discontinuous Galerkin methods and a new particle pusher for neutron star magnetosphere simulations

Kalapotharakos: Simulations vs observations


Discussion on modeling limitations: approximations, physical models and physical parameters, current and future limitations of computational power. Describe the current state-of-the-art. Quantify limitations. Model comparison. Disagreements between models.

The presenters of the various models may want to “defend” their work. The outcome of this discussion may be that all models are capable to produce all the answers consistent with observations, or that something is missing and that we need to invest in alternative numerical techniques, or new physical models.


Thursday Dec. 12: Beyond the current state-of-the-art

Discuss the prospects for future VHE pulsar observations. Determine which observations will allow us to differentiate between existing and future models that propose different possible VHE emission mechanisms and emission sites.

Discuss the prospects for future VHE gamma-ray emission modeling. Discuss the “hybrid” approach (combining global simulations with detailed localized particle simulations over the regions suspect for particle acceleration and high-energy emission). Prospects. Recommendations for implementation in the next 12 months:

Different sub teams will model the VHE observations of the three major pulsars and typical young and millisecond pulsars using archival/new observations.

One or several sub-teams will implement the Team’s recommendations for alternative numerical approaches and will obtain results for the same pulsars.

Prepare first draft of a review publication with the Team’s recommendations.


2nd Meeting in Bern, September 12-16, 2022

Monday Sep. 12: Novel numerical techniques

Emphasis on the equatorial current sheet as the origin of VHE gamma-ray emission. Focus on PIC and hybrid numerical simulations.

Cerutti: New results of large-scale PIC pulsar simulations

Petri: A relativistic particle pusher with realistic magnetic field strength (remotely)

Sudais: Hybrid pulsar simulations

Lyutikov: Inverse Compton model of pulsar gamma-ray emission

Harding: The separatrix current-sheet model for pulsar VHE emission (remotely)

Each review presentation + discussion: 1 ½ hours


Tuesday Sep. 13: Overview of VHE gamma-ray observations

3rd Fermi-LAT Catalogue. Fermi phenomenology (the fundamental plane).

Smith: Observed properties of GeV pulsars

Lyutikov: PeV emission from Crab coming from Fermi flares’ electrons

Kalapotharakos: Interpreting the Fermi pulsar phenomenology and beyond


Tuesday Se3. 10, 7 p.m.: Dinner, Restaurant Beaulieu


Wednesday Sep. 14: Overview of VHE gamma-ray observations

More gamma-ray pulsar observations. Prospects for the future

Djannati-Ataï: Vela HESS results (remotely)

Philippov: Coherent radio emission: results of PIC simulations (remotely)

Spitkovsky: Energy dissipation and emission in gamma-ray pulsars

Kalapotharakos: NICER results

Contopoulos: Our road to the reference 3D force-free solution

Kazanas: Summary (remotely)

Each review presentation + discussion: 1 ½ hours


Thursday Sep. 15: Discussions

Trying to understand if anything is wrong with the closed-line region Y-point. Why, in global PIC simulations, it is always lying a definite distance inside the light cylinder, and not on the light cylinder. Apparently this seems to be due to the inertia of the PIC super-particles in the numerical simulations.


Friday Sep. 16: Discussions

More discussions on the Y-point. Trying to understand the results of Hu & Beloborodov 2021.