Conveners
Multi-Messenger & Astro-Particle
- P.J. Meintjes (University of the Free State)
Active galactic nuclei (AGN) with relativistic jets, powered by mass accretion onto the central supermassive black hole of their host galaxies, are the most powerful persistent sources of broadband electromagnetic radiation in the Universe. Despite decades of multi-wavelength observations, there are still several key questions about AGN jet physics that remain open, such as "What is the plasma...
Blazars are potential candidates of cosmic-ray (CR) acceleration up to ultrahigh energies (UHE, E > 1017 eV). Association of a number of blazars with IceCube neutrino events supports this hypothesis. If the intergalactic magnetic field strength is reasonably low, the UHECRs escaping from the blazar jet will produce neutrinos and gamma rays along the line-of-sight (LoS) by interacting with the...
In 2015 the advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO) detected the first ever gravitational event, gravitational wave event GW150914, with multiple new gravitational wave events, originating from both binary neutron stars and binary black hole (BBH) mergers, detected in subsequent years. In light of these detections, we simulate the dynamics of ambient test particles...
Ultraluminous X-ray sources (ULXs) were first discovered in the 1980s by the Einstein Observatory. The most interesting property of ULXs is that they exceed the Eddington luminosity of a neutron star. Data from the 2XMM-Newton and Chandra contain 470 ULX candidates in 238 galaxies (Walton et al. 2011) and 629 ULX candidates in 309 galaxies (Kovlakas et al. 2020), respectively. In this study,...
Emerging anomalies in both di and multi-lepton data from the LHC have been used to motivate for an extension to the Standard Model in the form of a second Higgs doublet and a singlet scalar (2HDM+S). Here we explore a dark matter candidate drawn from this model: a scalar particle that couples to the Standard Model through the 2HDM+S degrees of freedom. Using the best-fit 2HDM+S model from LHC...
Blazars are powered by super-massive black holes in their centers and are known for extreme variability on time scales from minutes to years. In case of a binary black hole system, this duality is traceable as periodic modulation of their gamma-ray emission. So far, high-significance periodicity has been reported for a very few blazars with standard approaches. We developed a method to search...
Useful to LIGO detections would be an electromagnetic signal which heralds the start of a binary black hole inspiral. Primarily, this would also aid in multi-messenger follow-up studies. We look to the potential presence of an accretion disk as a source of emissions. We consider this problem by computing geodesics numerically from an approximate, analytic metric to determine the amount of...
