Pulsars, transients and relativistic astrophysics

Abstract:

The interaction of gravitational waves (GWs) with matter is thought to be typically negligible in the Universe. We identify an exception in the case of resonant interactions, where GWs emitted by a background binary system, such as an inspiraling supermassive black hole (SMBH) binary, cause a resonant response in a stellar-mass foreground binary and the frequencies of the two systems become, and remain, synchronized. We point out that this previously unexplored dynamical phenomenon is not only possible, but can lead to $\mathcal{O}(30)$ binary systems becoming resonantly locked in the host galaxy of merging SMBHs of mass ${10}^{8.5-11}{M}_{\odot }$ , each of which has a significantly reduced merger time. We predict $\mathcal{O}({10}^{10})$ binary systems have been locked in the Universe’s history. Resonant locking could be detected through anomalous inspiral of binary systems.

Abstract:

Abstract The origin of cosmic rays from outside the Solar system are unknown, as they are deflected by the interstellar magnetic field. Supernova remnants are the main candidate for cosmic rays up to PeV energies but due to lack of evidence, they cannot be concluded as the sources of the most energetic Galactic CRs. We investigate discrete ejecta produced in state transitions of black hole X-ray binary systems as a potential source of cosmic rays, motivated by recent >100 TeV γ-ray detections by LHAASO. Starting from MAXI J1820+070, we examine the multi-wavelength observations and find that efficient particle acceleration may take place (i.e. into a robust power-law), up to ∼2 × 1016μ−1/2 eV, where μ is the ratio of particle energy to magnetic energy. From these calculations, we estimate the global contribution of ejecta to the entire Galactic spectrum to be $\sim 1~{{\ \rm per\ cent}}$, with the cosmic ray contribution rising to $\sim 5~{{\ \rm per\ cent}}$ at PeV energies, assuming roughly equal energy in non-thermal protons, non-thermal electrons and magnetic fields. In addition, we calculate associated γ-ray and neutrino spectra of the MAXI J1820+070 ejecta to investigate new detection methods with CTAO, which provide strong constraints on initial ejecta size of order 107 Schwarzschild radii (10−5 pc) assuming a period of adiabatic expansion.

Abstract:

The origin of cosmic rays (CRs) from outside the Solar system is unknown, as they are deflected by the interstellar magnetic field. Supernova remnants are the main candidate for CRs up to PeV energies but due to lack of evidence, they cannot be concluded as the sources of the most energetic Galactic CRs. We investigate discrete ejecta produced in state transitions of black hole X-ray binary systems as a potential source of CRs, motivated by recent TeV -ray detections by LHAASO. Starting from MAXI J1820+070, we examine the multi-wavelength observations and find that efficient particle acceleration may take place (i.e. into a robust power law), up to eV, where is the ratio of particle energy to magnetic energy. From these calculations, we estimate the global contribution of ejecta to the entire Galactic spectrum to be , with the CR contribution rising to at PeV energies, assuming roughly equal energy in non-thermal protons, non-thermal electrons, and magnetic fields. In addition, we calculate associated -ray and neutrino spectra of the MAXI J1820+070 ejecta to investigate new detection methods with CTAO, which provide strong constraints on initial ejecta size of order Schwarzschild radii ( pc) assuming a period of adiabatic expansion.

Abstract:

Abstract We investigate the relationship between disc winds, radio jets, accretion rates and black hole masses of a sample of ∼100k quasars at z ≈ 2. Combining spectra from the 17th data release of the Sloan Digital Sky Survey (SDSS) with radio fluxes from the 2nd data release of the Low Frequency ARray (LOFAR) Two-Meter Sky Survey (LoTSS), we statistically characterise a radio loud and radio quiet population using a two-component Gaussian Mixture model, and perform population matching in black hole mass and Eddington fraction. We determine how the fraction of radio loud sources changes across this parameter space, finding that jets are most efficiently produced in quasars with either a very massive central black hole (MBH > 109M⊙) or one that is rapidly accreting (λEdd > 0.3). We also show that there are differences in the blueshift of the $\textrm {C}\, \rm \small {IV}$ λ1549Å line and the equivalent width of the $\rm {He}\, \rm \small {II}$ λ1640Å line in radio loud and radio quiet quasars that persist even after accounting for differences in the mass and accretion rate of the central black hole. Generally, we find an anti-correlation between the inferred presence of disc winds and jets, which we suggest is mediated by differences in the quasars’ spectral energy distributions. The latter result is shown through the close coupling between tracers of wind kinematics and the ionising flux– which holds for both radio loud and radio quiet sources, despite differences between their emission line properties– and is hinted at by a different Baldwin effect in the two populations.