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We find statistical evidence for a mismatch between the (global) spatial curvature parameter $K$ in the geodesic equation for incoming photons, and the corresponding parameter in the Friedmann equation that determines the time evolution of the background spacetime and its perturbations. The mismatch hereafter referred to as `curvature-slip' is especially evident when the SH0ES prior on the current expansion rate is assumed. This result is based on joint analyses of cosmic microwave background (CMB) observations with the PLANCK satellite (P18), first year results of the Dark Energy Survey (DES), Baryonic Oscillation (BAO) data, and - at a lower level of significance - also on Pantheon SNIa (SN) catalog. For example, the betting odds against the Null Hypothesis are greater than $10^7$:1, 1400:1 and 1000:1 when P18+SH0ES, P18+DES+SH0ES, and P18+BAO+SH0ES, respectively, are considered. Datasets involving SNIa weaken this curvature slip considerably. Notably, even when the SH0ES prior is not imposed the betting odds for the rejection of the Null Hypothesis are 70:1 and 160:1 in cases where P18+DES and P18+BAO are considered. When the SH0ES prior is imposed, global fit of the modified model (that allows for a nonvanishing `curvature slip') strongly outperforms that of $\Lambda$CDM as is manifested by significant Deviance Information Criterion (DIC) gains, ranging between 7 and 23, depending on the dataset combination considered. Even in comparison to K$\Lambda$CDM the proposed model results in significant, albeit smaller, DIC gains when SN data are excluded. Our finding could possibly be interpreted as an inherent inconsistency between the (idealized) maximally symmetric nature of the FRW metric, and the dynamical evolution of the GR-based homogeneous and isotropic $\Lambda$CDM model (abridged), Comment: Submitted. Comments are welcome

Spiral galaxies M31 and M33 are Fermi/LAT-detected gamma-ray sources. We model the broadband non-thermal (NT) emission of the central region of M31 (R < 5.5 kpc) and of the disk of M33 (R ~ 9 kpc). For either galaxy, we self-consistently model the broadband SED of the diffuse NT emission based on published radio and gamma-ray data. All relevant radiative processes involving relativistic and thermal electrons (synchrotron, Compton scattering, bremsstrahlung, and free-free emission and absorption), along with relativistic protons (neutral-pion decay following interaction with thermal protons), are considered, using exact emissivity formulae. We also use the Fermi/LAT validated gamma-ray emissivities for pulsars. We find that, in both sources, the radio emission is composed of primary and secondary electron synchrotron and thermal bremsstrahlung. The M33 gamma-ray emission appears to be mainly hadronic, similar to the Magellanic Clouds (Persic & Rephaeli 2022). In contrast, we find suggestions of a more complex situation in the central region of M31, whose emission could be a mix of pulsar emission and hadronic emission, with the latter possibly originating from both the disk and the vicinity of the nuclear black hole. The alternative modelling of the spectra of M31 and M33 is motivated by the different hydrogen distribution in the two galaxies: the hydrogen deficiency in the central region of M31 partially unveils emissions from the nuclear BH and the pulsar population in the bulge and inner disk. If this were to be the case in M33 as well, these emissions would be outshined by diffuse pionic emission originating within the flat central-peak gas distribution in M33., Comment: 19 pages, 4 figures, 2 appendices. References updated, typos corrected

Detailed modelling of the spectro-spatial distributions of energetic electrons and protons in galactic discs and haloes of starburst galaxies (SBGs) is needed in order to follow their interactions with the magnetized interstellar medium and radiation fields, determine their radiative yields, and for estimating their residual spectral densities in intergalactic environments. We have developed a semi-analytical approach for calculating the particle spectro-spatial distributions in the disc and halo based on a diffusion model for particle propagation from acceleration sites in the central SB and disc regions, including all their relevant interaction modes. Important overall normalization of our models is based on previous modelling of the Galactic disc (with the GALPROP code), scaled to the higher star-formations rate in NGC253, and on spatially resolved radio measurements of the central SB and disc. These provide the essential input for determining the particle distributions and their predicted radiative yields in the outer disc and inner halo for a range of values of the key parameters that affect diffusion rate and energy losses. Results of our work clearly indicate that quantitative description of non-thermal emission in SBGs has to be based on modelling of the particle distributions in the entire disc, not just the central SB region., Comment: 11 pages, 3 figures