Peter Mészáros

Methods for testing a control unit of a vehicle. The control unit obtains calculated surrounding-area data of a simulated surround sensor, and obtains calculated motion data of a simulated vehicle. The calculated motion data are transmitted to the control unit via a simulated vehicle data bus. Using a sensor testing unit, the calculated surrounding-area data are transmitted to the control unit via a sensor-data transmission circuit different from the vehicle data bus. To execute a simulated acquisition of surrounding-area data, using the control unit, a command for executing a measurement is transmitted to the sensor testing unit, data for identifying the position of the simulated surround sensor is transmitted to the computer device, positions of points of reflection by simulated objects in the surrounding area of the vehicle are calculated and transmitted to the sensor testing unit, and calculated surrounding-area data are …

We study cosmological perturbations in a universe with only one matter component described by a triplet of fields. Configuration of these fields is the same as for body coordinates of a solid, and they enter the matter Lagrangian only through the kinetic term. We restrict ourselves only to cases with constant pressure to energy density ratio w. Superhorizon perturbations have no constant modes with scalar vector and tensor perturbations decaying or growing at different rates, and in cases with pressure to energy density ratio w>(19− 8 7)/3= ̇− 0. 722 perturbations propagate with superluminal sound speed. Regarding our universe, these results illustrate possible challenges with comparing the observational data to models similar to solid inflation, if the inflation is followed by a period during which the studied model is a sufficiently good approximation.

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The detection of the hyper-bright gamma-ray burst (GRB) 221009A enables us to explore the nature of the GRB emission and the origin of very high-energy gamma rays. We analyze the Fermi Large Area Telescope (Fermi-LAT) data of this burst and investigate the GeV–TeV emission in the framework of the external reverse-shock model. We show that the early∼ 1–10 GeV emission can be explained by the external inverse-Compton mechanism via upscattering MeV gamma rays by electrons accelerated at the reverse shock, in addition to the synchrotron self-Compton component. The predicted early optical flux could have been brighter than that of the naked-eye GRB 080319B. We also show that proton synchrotron emission from accelerated ultrahigh-energy cosmic rays (UHECRs) is detectable and could potentially explain≳ TeV photons detected by LHAASO or constrain the UHECR acceleration mechanism. Our …

The joint detection of gravitational waves and the gamma-ray counterpart of a binary neutron star merger event, GW170817, unambiguously validates the connection between short gamma-ray bursts and compact binary object (CBO) mergers. We focus on a special scenario where short gamma-ray bursts produced by CBO mergers are embedded in disks of active galactic nuclei (AGNs), and we investigate the γ-ray emission produced in the internal dissipation region via synchrotron, synchrotron self-Compton, and external inverse Compton (EIC) processes. In this scenario, isotropic thermal photons from the AGN disks contribute to the EIC component. We show that a low-density cavity can be formed in the migration traps, leading to the embedded mergers producing successful GRB jets. We find that the EIC component would dominate the GeV emission for typical CBO mergers with an isotropic-equivalent …

The Universe is filled with a diffuse background of MeV gamma-rays and PeV neutrinos, whose origins are unknown. Here, we propose a scenario that can account for both backgrounds simultaneously. Low-luminosity active galactic nuclei have hot accretion flows where thermal electrons naturally emit soft gamma rays via Comptonization of their synchrotron photons. Protons there can be accelerated via turbulence or reconnection, producing high-energy neutrinos via hadronic interactions. We demonstrate that our model can reproduce the gamma-ray and neutrino data. Combined with a contribution by hot coronae in luminous active galactic nuclei, these accretion flows can explain the keV – MeV photon and TeV – PeV neutrino backgrounds. This scenario can account for the MeV background without non-thermal electrons, suggesting a higher transition energy from the thermal to nonthermal Universe than …

The recent detection of TeV photons from two gamma-ray bursts (GRBs), GRB 190114C and GRB 180720B, has opened a new window for multimessenger and multiwavelength astrophysics of high-energy transients. We study the origin of very high energy (VHE) γ-rays from the short GRB 160821B, for which the MAGIC Collaboration reported a∼ 3σ statistical significance. Short GRBs are often accompanied by extended and plateau emission, which is attributed to internal dissipation resulting from activities of a long-lasting central engine, and Murase et al.(2018) recently suggested the external inverse-Compton (EIC) scenario for VHE counterparts of short GRBs and neutron star mergers. Applying this scenario to GRB 160821B, we show that the EIC flux can reach∼ 10− 12 erg cm− 2 s− 1 within a time period of∼ 10 3–10 4 s, which is consistent with the MAGIC observations. EIC γ-rays expected during the …

For a perfect fluid, the quantity defined through mixed components of the stress–energy tensor is independent on the choice of coordinates only for two values of the pressure to energy density ratio w= p/ρ: for radiation with w= 1/3, and for dark energy with w=− 1. With other choices of w, the quantity is coordinate dependent, and only in the local rest frame of the fluid. We show that the same is true also for solid matter with shear stress Lamé coefficient set to zero in a flat Friedmann–Lemaître–Robertson–Walker Universe with perturbed metric as well as stress–energy tensor. We call the two different solids with coordinate independent radiation-like solid and dark energy-like solid, and we restrict ourselves to these two special cases. By analysing second order perturbations we discover two one parametric sets of such solid matter models containing special cases of radiation and dark …