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Abstract:Pulsar winds have been shown to be preferred sites of particle acceleration and high-energy radiation. Models have been constructed in order to better characterize their general structure in isolated systems. However, most of the galactic millisecond pulsars find themselves in binary systems. In this talk, I present the first Particle-in-cell (PIC) simulations of both the pulsar magnetosphere and the wind of the pulsar interacting with an unmagnetized spherical companion. This work considers a generic case that could be applied to various companions including planets, asteroids, white dwarfs, or even neutron stars. Our results show evidence of an enhanced conversion of Poynting flux into particle acceleration, via forced reconnection in the outflowing wind near the companion. Hence, the high-energy synchrotron radiation is also amplified and takes the form of an orbital-modulated hollow cone of light. We do not exclude long-period radio transient counterparts, that would be of significant interest, especially in the light of the recently discovered galactic long-period radio transients. Slides available here: https://www.ntnu.no/wiki/download/attachments/195538250/NTNU_seminar_VRR.pdf?api=v2
- 24.10. Luca Comisso* (Columbia University): Particle acceleration in highly magnetized plasmas *remote seminar, exceptionally on Thursday 4PM in D5-106
Video available here: https://www.youtube.com/watch?v=_KxfrVZkamE
- 03.12. Karri Koljonen (IFY, NTNU): Cosmic-neighbor-associated distances to blazars
Abstract: Blazars are active galactic nuclei with relativistic jets directed toward Earth. Relativistic beaming amplifies their brightness, making them appear extremely luminous across multiple wavelengths, from radio to gamma-rays. Consequently, blazars are the most numerous source class among very high-energy gamma-ray emitters. However, determining their redshifts is often challenging because jet emission can obscure spectral lines from the host galaxy or intervening matter. In this talk, I will introduce two methods for estimating blazar distances by associating them with their "cosmic neighborhood". These techniques involve analyzing the optical fields around a blazar using either multi-object spectroscopy or multi-band photometry, combined with the assumption that blazars are typically located in galaxy-rich environments. Accurate redshift estimation for high-redshift blazars is crucial for advancing our understanding of extragalactic very high-energy gamma-ray sources and their interactions with the surrounding universe. Slides available here: https://www.ntnu.no/wiki/download/attachments/195538250/NTNU_seminar_Koljonen.pdf?api=v2