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| Abstract: Star-forming regions (SFRs) are known sites of particle acceleration and may potentially be important sources of gamma-rays in the Galaxy. While a few Galactic SFRs have been associated with gamma-ray sources, the majority lack detections. Using all available Fermi data in combination with improved optical measurements, we are performing a systematic study of Galactic SFRs. The goal of our systematic study is to characterize the morphology and spectral emission of Galactic SFRs, and understand their energetics and particle acceleration processes. In this talk I will discuss the preliminary results of this project focusing on the connection of SFRs’ emission and their physical properties. |
Pranab Deka - "Exponential Methods for Anisotropic Diffusion"
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| Abstract: Anisotropic diffusion is imperative in understanding cosmic ray diffusion across the Galaxy, the heliosphere, and the interplay of cosmic rays with the Galactic magnetic field. The diffusion term contributes to the highly-stiff nature of the cosmic ray transport equation. In order to conduct numerical simulations of time-dependent cosmic ray transport, the implicit Crank-Nicolson integrator has been traditionally favoured over the CFL-bound explicit integrators to be able to take large time-step sizes. We propose exponential methods that directly compute the exponential of the underlying matrix (or the exponential-like functions) to treat the linear anisotropic diffusion equation. We consider time-dependent sources to emulate cosmic rays being ejected into the Galaxy at different points in time. We compare and contrast the performance of two second-order and one fourth-order exponential quadrature methods with that of Crank-Nicolson. The exponential methods allow us to take substantially large time-step sizes, thereby reducing the computational cost by almost an order of magnitude. The accuracy of the second-order exponential methods is similar to that of Crank-Nicolson (as one would expect) whilst the fourth-order solver yields highly accurate solutions. The boost in the performance offered by the exponential methods without compromising the accuracy of the solutions makes them an excellent alternative to the traditional methods for treating the time-dependent cosmic ray transport equation. |
Zachary Metzler - "Opportunities for Multimessenger Observations of Millisecond Pulsars"
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| Abstract: The first gravitational wave was detected by LIGO in 2015, and since that time over 100 events have been detected. However, these detections have been transient signals from binary mergers of black holes and neutron stars. In addition to transient, LIGO is sensitive to continuous gravitational waves. Millisecond pulsars are strong candidates for continuous gravitational waves, since the accretion from a nearby star can sustain spins >500 Hz and the accreting matter provides an inherent ellipticity. I will discuss the relationship between ellipticity, accretion rate, and gamma ray emission as well as discuss prospects for directly measuring these in the near future. |
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| Abstract: Gravitational waves were detected in 2015 for the first time. In 2017, gravitational waves from a binary neutron star merger were detected in coincidence with a gamma-ray burst (GRB) confirming that some short events are produced by mergers. The multi-messenger astrophysics era began, and the discovery highlighted the importance of space missions to detect and localise bursts at a time when gravitational wave systems are becoming more sensitive to merger events. Currently there is a lack of large future gamma-ray missions to enable similar measurements and scientific discovery. Consequently we propose to build Gamma-ray Investigation of the Full Transient Sky (GIFTS), a novel 6U CubeSat, which has been designed, prototyped and demonstrated previous work by the PI. The proposed design is based on detailed in-house instrument development and on the gamma-ray detector in the 2U CubeSat EIRSAT-1 which launched in 2023. GIFTS will comprise six gamma-ray detectors and will detect and localise 70 GRBs per year including 11 short GRBs. Detailed design and simulations demonstrate it will detect up to 2 GRBs per year coincident with GW detections. We will build and prepare GIFTS for operation when GW detectors reach peak sensitivity. |
Zoe Brisson-Tsavoussis - 1-slide
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IceCube: Gen2 Prototype, Southern Sky eHBLs
Ieva Jankute
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