Questioning the H0H_0 tension via the look-back time

The Hubble tension is investigated taking into account the cosmological look-back time. Specifically, considering a single equation, widely used in standard cosmology, it is possible to recover both values of the Hubble constant $H_0$ reported by the SH0ES and Planck collaborations: the former is obtained through cosmological ladder methods (e.g. Cepheids, Supernovae Type IA) and the latter through measurements of the Cosmic Microwave Background. Also, other values obtained in the literature are achieved with the same approach. We conclude that the Hubble tension can be removed if the look-back time is correctly referred to the redshift where the measurement is performed.Comment: 8 pages, 1 figure, accepted for publication in Physics of the Dark Univers

Investigating dark energy by electromagnetic frequency shifts II: the Pantheon+ sample

International audienceFollowing results presented in Eur. Phys. J. Plus, {\bf 137} (2022) 253 by the same authors, we investigate the observed red shift $z$, working under the hypothesis that it might be composed by the expansion red shift $z_{\rm C}$ and an additional frequency shift $z_{\rm S}$, towards the red or the blue, due to Extended Theories of Electromagnetism (ETE). We have tested this prediction considering the novel Pantheon+ Catalogue, composed by 1701 light curves collected by 1550 SNe Ia, and 16 BAO data, for different cosmological models characterised by the absence of a dark energy component. In particular, we shall derive which values of $z_{\rm S}$ match the observations, comparing the new results with the ones obtained considering the older Pantheon Catalogue. We find interesting differences in the resulting $z_{\rm S}$ distributions, highlighted in the text. Later, we also add a discussion regarding Extended Theories of Gravity and how to incorporate them in our methodology

Investigating dark energy by electromagnetic frequency shifts II: the Pantheon+ sample

International audienceFollowing results presented in Eur. Phys. J. Plus, {\bf 137} (2022) 253 by the same authors, we investigate the observed red shift $z$, working under the hypothesis that it might be composed by the expansion red shift $z_{\rm C}$ and an additional frequency shift $z_{\rm S}$, towards the red or the blue, due to Extended Theories of Electromagnetism (ETE). We have tested this prediction considering the novel Pantheon+ Catalogue, composed by 1701 light curves collected by 1550 SNe Ia, and 16 BAO data, for different cosmological models characterised by the absence of a dark energy component. In particular, we shall derive which values of $z_{\rm S}$ match the observations, comparing the new results with the ones obtained considering the older Pantheon Catalogue. We find interesting differences in the resulting $z_{\rm S}$ distributions, highlighted in the text. Later, we also add a discussion regarding Extended Theories of Gravity and how to incorporate them in our methodology

Diffusion Properties of a Brownian Ratchet with Coulomb Friction

The motion of a Brownian particle in the presence of Coulomb friction and an asymmetric spatial potential was evaluated in this study. The system exhibits a ratchet effect, i.e., an average directed motion even in the absence of an external force, induced by the coupling of non-equilibrium conditions with the spatial asymmetry. Both the average motion and the fluctuations of the Brownian particle were analysed. The stationary velocity shows a non-monotonic behaviour as a function of both the temperature and the viscosity of the bath. The diffusion properties of the particle, which show several time regimes, were also investigated. To highlight the role of non-linear friction in the dynamics, a comparison is presented with a linear model of a Brownian particle driven by a constant external force, which allows for analytical treatment. In particular, the study unveils that the passage times between different temporal regimes are strongly affected by the presence of Coulomb friction

Investigating dark energy by electromagnetic frequency shifts

International audienceThe observed red shift z might be composed by the expansion red shift $z_\mathrm{C}$ and an additional frequency shift $z_\mathrm{S}$, towards the red or the blue, by considering extended theories of electromagnetism (ETE). Indeed, massive photon theories—the photon has a real mass as in the de Broglie–Proca theory or an effective mass as in the standard-model extension, based on Lorentz–Poincaré symmetry violation (LSV)—or nonlinear electromagnetism theories may induce a cosmological expansion-independent frequency shift in the presence of background (inter-) galactic electromagnetic fields, and where of relevance LSV fields, even when both fields are constant. We have tested this prediction considering the Pantheon Catalogue, composed by 1048 SNe Ia, and 15 BAO data, for different cosmological models characterised by the absence of a cosmological constant. From the data, we compute which values of $z_\mathrm{S}$ match the observations, spanning cosmological parameters ($\Omega$ densities and Hubble–Lemaître constant) domains. We conclude that the frequency shift $z_\mathrm{S}$ can support an alternative to accelerated expansion, naturally accommodating each SN Ia position in the distance modulus versus red shift diagram, due to the light-path dependency of $z_\mathrm{S}$. Finally, we briefly mention laboratory test approaches to investigate the additional shift from ETE predictions

Questioning the H<SUB>0</SUB> tension via the look-back time

International audienceThe Hubble tension is investigated taking into account the cosmological look-back time. Specifically, considering a single equation, widely used in standard cosmology, it is possible to recover both values of the Hubble constant H0 reported by the SH0ES and Planck collaborations: the former is obtained through cosmological ladder methods (e.g. Cepheids, Supernovae Type IA) and the latter through measurements of the Cosmic Microwave Background. Also, other values obtained in the literature are achieved with the same approach. We conclude that the Hubble tension can be removed if the look-back time is correctly referred to the redshift where the measurement is performed

Testing the Ampère-Maxwell law on the photon mass and Lorentz-Poincaré symmetry violation with MMS multi-spacecraft data

International audienceThe photon is commonly believed being the only free massless particle. Deviations from the Ampère-Maxwell law, due to a photon mass, real for the de Broglie-Proca theory, or effective for the Lorentz-Poincaré Symmetry Violation (LSV) in the Standard-Model Extension (SME) were sought in six years of MMS satellite data. In a minority of cases, out of which $76\%$ in modulus and $65\%$ in Cartesian components for the highest time resolution burst data and best tetrahedron configurations in the solar wind and peripheries, deviations have been found. After currents error analysis, the minimal photon mass would be $1.74 \times 10^{-53}$ kg while the minimal LSV parameter $|\vec{k}^{\rm AF}|$ value would be $4.95 \times 10^{-11}$ m$^{-1}$. These values are compared with actual limits and discussed

Optical and X-ray GRB Fundamental Planes as Cosmological Distance Indicators

Gamma-Ray Bursts (GRBs), can be employed as standardized candles, extending the distance ladder beyond Supernovae Type Ia (SNe Ia, $z=2.26$). We standardize GRBs using the 3D fundamental plane relation (the Dainotti relation) among the rest-frame end time of the X-ray plateau emission, its corresponding luminosity, and the peak prompt luminosity. Combining SNe Ia and GRBs, we constrain $\Omega_{\text{M}}= 0.299 \pm 0.009$ assuming a flat $\Lambda$CDM cosmology with and without correcting GRBs for selection biases and redshift evolution. Using a 3D optical Dainotti correlation, we find this sample is as efficacious in the determination of $\Omega_{\text{M}}$ as the X-ray sample. We trimmed our GRB samples to achieve tighter planes to simulate additional GRBs. We determined how many GRBs are needed as standalone probes to achieve a comparable precision on $\Omega_{\text{M}}$ to the one obtained by SNe Ia only. We reach the same error measurements derived using SNe Ia in 2011 and 2014 with 142 and 284 simulated optical GRBs, respectively, considering the errorbars on the variables halved. These error limits will be reached in 2038 and in 2047, respectively. Using a doubled sample (obtained by future machine learning approaches allowing a lightcurve reconstruction and the estimates of GRB redhifts when z is unknown) compared to the current sample, with errorbars halved we will reach the same precision as SNe Ia in 2011 and 2014, now and in 2026, respectively. If we consider the current SNe precision, this will be reached with 390 optical GRBs by 2054.Comment: 31 pages, 17 figures, 10 table