We discuss various aspects of the post-Newtonian approximation in general relativity. After presenting the foundation based on the Newtonian limit, we show a method to derive post-Newtonian equations of motion for relativistic compact binaries based on a surface integral approach and the strong field point particle limit. As an application we derive third post-Newtonian equations of motion for relativistic compact binaries which respect the Lorentz invariance in the post-Newtonian perturbative sense, admit a conserved energy, and are free from any ambiguity.
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http://dx.doi.org/10.12942/lrr-2007-2 | DOI Listing |
Phys Rev Lett
December 2024
Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland.
We performed the first simulations of accretion onto the compact objects in the Reissner-Nordström (RN) space-time. The results obtained in general relativity are representative of those for spherically symmetric naked singularities and black holes in a number of modified gravity theories. A possible application of these calculations is to the active galactic nuclei with their powerful jets and outflows.
View Article and Find Full Text PDFNature
January 2025
Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
Nat Commun
August 2024
Department of Physics and Astronomy, UCLA, 405 Hilgard Avenue, Los Angeles, CA, USA.
Free-electron-lasers fill a critical gap in the space of THz-sources as they can reach high average and peak powers with spectral tunability. Using a waveguide in a THz FEL significantly increases the coupling between the relativistic electrons and electromagnetic field enabling large amounts of radiation to be generated in a single passage of electrons through the undulator. In addition to transversely confining the radiation, the dispersive properties of the waveguide critically affect the velocity and slippage of the radiation pulse which determine the central frequency and bandwidth of the generated radiation.
View Article and Find Full Text PDFSensors (Basel)
August 2024
Stefan Batory Academy of Applied Sciences, Stefana Batorego 64C, 96-100 Skierniewice, Poland.
SQM-ISS is a detector that will search from the International Space Station for massive particles possibly present among the cosmic rays. Among them, we mention strange quark matter, Q-Balls, lumps of fermionic exotic compact stars, Primordial Black Holes, mirror matter, Fermi balls, etc. These compact, dense objects would be much heavier than normal nuclei, have velocities of galaxy-bound systems, and would be deeply penetrating.
View Article and Find Full Text PDFNanomaterials (Basel)
August 2024
Guangxi Key Laboratory of Multimedia Communications and Network Technology, School of Computer, Electronics and Information, Guangxi University, Nanning 530004, China.
Optical logic devices are essential functional devices for achieving optical signal processing. In this study, we design an ultra-compact (4.92 × 2.
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