The brightest cosmic gamma-ray burst (GRB) ever detected, GRB 221009A, wasaccompanied by photons of very high energies. These gamma rays may be used totest both the astrophysical models of the burst and our understanding oflong-distance propagation of energetic photons, including potential new-physicseffects. Here we present the observation of a photon-like air shower with theestimated primary energy of $300^{+43}_{-38}$ TeV, coincident (with the chanceprobability of $\sim 9\cdot 10^{-3}$) with the GRB in its arrival direction andtime. Making use of the upgraded Carpet-3 muon detector and new machinelearning analysis, we estimate the probability that the primary was hadronic as$\sim 3 \cdot 10^{-4}$. This is the highest-energy event ever associated withany GRB.
The infrared (IR) to X-ray luminosity ratio (IRX) is an indicator of the roleof the dust plays in cooling of hot gas in supernova remnants (SNR). Using the3D dynamics of gas and interstellar polydisperse dust grains we analyze theevolution of SNR in the inhomogeneous medium. We obtain spatial distributionsof the surface brigthness both of the X-ray emission from hot gas inside SNRand the IR emission from the SNR swept-up shell, as well as, the average gastemperature in the SNR, $T_X$. We find that the IRX changes significantly (by afactor of $\sim 3-30$) as a function of impact distance within the SNR and itsage. In a low inhomogeneous medium the IRX drops rapidly during the SNRevolution. On the other hand, if large inhomogeneities are present in themedium, the IRX is maintained at higher levels during the late SNR evolution atradiative phase due to replenishment of dust in the hot gas by incompletelydestroyed fragments behind the shock front. We show that the onset of theradiative phase determines the evolution of the $T_X - {\rm IRX}$ diagram. Weillustrate that decreasing gas metallicity or density leads to high values oftemperature and IRX ratio. We discuss how our results can be applied to theobservational data to analyse the SNR older than 10 kyr (i.e. when the mass ofthe swept-up dust in the shell is expected to exceed that produced in the SNR)in the Galaxy and Large Magellanic Cloud.