A class of viable F(R) gravity models which can provide a unified description of inflation with the dark energy era is confronted with the latest observational data on the dark energy era. These models have the unique characteristic that the de Sitter scalaron mass in the Einstein frame counterpart theory is a monotonic function of the curvature, which renders them viable descriptions for both the inflationary and the late-time acceleration eras. We also compare these models with other wellknown viable F(R) gravity models and with the Lambda-Cold-Dark-Matter model. As we show, the most phenomenologically successful models are those which deviate significantly from the Lambda-Cold-Dark-Matter model. Also some of the models presented, provide a statistically favorable description of the dark energy eras, compared with the exponential F(R) gravity model and of course compared with the Lambda-Cold-Dark-Matter model. All the models we present in this article are confronted with the observational data from the Planck collaboration, the Pantheon plus data from Type Ia supernovae, the two rounds of observations of the Dark Energy Spectroscopic Instrument, data from baryon acoustic oscillations and the Hubble constant measurements. As we show, two of the models are statistically favorable by the data.
We show that spin chains in thermal equilibrium have a correlation structure in which individual regions are strongly correlated at most with their near vicinity. We quantify this with alternative notions of the conditional mutual information, defined through the so-called Belavkin-Staszewski relative entropy. We prove that these measures decay superexponentially at every positive temperature, under the assumption that the spin chain Hamiltonian is translation-invariant. Using a recovery map associated with these measures, we sequentially construct tensor network approximations in terms of marginals of small (sublogarithmic) size. As a main application, we show that classical representations of the states can be learned efficiently from local measurements with a polynomial sample complexity. We also prove an approximate factorization condition for the purity of the entire Gibbs state, which implies that it can be efficiently estimated to a small multiplicative error from a small number of local measurements. The results extend from strictly local to exponentially-decaying interactions above a threshold temperature, albeit only with exponential decay rates. As a technical step of independent interest, we show an upper bound to the decay of the Belavkin-Staszewski relative entropy upon the application of a conditional expectation.
Active galactic nuclei (AGNs), star formation (SF), and galaxy interactions can drive turbulence in the gas of the interstellar medium (ISM), which, in turn, plays a role in SF taking place within galaxies. The impact on molecular gas is of particular importance, as it serves as the primary fuel for SF. Our goal is to investigate the origin of turbulence and the emission of molecular gas, as well as low-and-intermediate-ionisation gas, in the inner few kpc of both AGN hosts and star-forming galaxies (SFGs). We used archival JWST MIRI/MRS observations of a sample consisting of 54 galaxies at z < 0.1. We present flux measurements for the H2 S(5)λ6.9091 μm, [ArII]λ6.9853 μm, [FeII]λ5.3403 μm, and [ArIII]λ8.9914 μm emission lines along with velocity dispersion estimated by the W80 parameter. For galaxies with coronal line emission, we included measurements of the [MgV]λ5.6098 μm line. We compared the line ratios to photoionisation and shock models to explore the origin of the gas emission. AGNs exhibit broader emission lines than SFGs, with the largest velocity dispersions observed in radio-strong (RS) AGNs. The H2 gas is less turbulent compared to ionised gas, while coronal gas presents higher velocity dispersions. The W80 values for the ionised gas show a decrease when going from the nucleus out to radii of approximately 0.5–1 kpc, followed by an outward increase up to 2–3 kpc. In contrast, the H2 line widths generally display increasing profiles with distance from the center. Correlations between the W80 parameter and line ratios such as H2S(5)/[Ar II] and [Fe II]/[Ar II] indicate that the most turbulent gas is associated with shocks, enhancing H2 and [Fe II] emissions. Based on the observed line ratios and velocity dispersions, the [FeII] emission is consistent with predictions of fast shock models, while the H2 emission is likely associated with molecules formed in the post-shock region. We speculate that these shocked gas regions are produced by AGN outflows and jet-cloud interactions in AGN-dominated sources; whereas in SFGs, they might be created through stellar winds and mergers. This shock-induced gas heating may be an important mechanism of AGN (or stellar) feedback, preventing the gas from cooling and forming new stars.
The simultaneous increase in energy use and CO2 emissions poses a serious environmental threat. Efficient technologies that produce low-carbon energy vectors from methane through CO2 recycling offer promising solutions. Hydrogen, a lightweight energy vector with high energy content, ease of storage, and large-scale production potential, emits no direct pollutants and can be generated from various low-carbon sources. Chemical looping technologies are effective for hydrogen production due to their high energy efficiency and inherent CO2 capture. This study investigates chemical looping technologies for hydrogen production through multiple redox cycles, alternating methane fuel steps with oxidation steps in air or CO2 to restore the catalysts and remove carbon. For this reason, five nickel-based catalysts were tested: Ni coprecipitated with cerium oxide, Ni impregnated on lab-made ceria, NiMgAl and NiCaAl mixed oxides from hydrotalcite-like precursors, and a LaNi0.8Co0.2O3 perovskite oxide. Results show hydrogen production efficiency and catalyst stability are strongly influenced by the oxidation atmosphere as well as by the materials redox properties and the nickel chemical environment.
We present the measurements and constraints of intrinsic alignments (IAs) in the Physics of the Accelerating Universe Survey (PAUS) deep wide fields, which include the W1 and W3 fields from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) and the G09 field from the Kilo-Degree Survey (KiDS). Our analyses cover 51deg(2), in the photometric redshift (photo-z) range 0.1 < z(b) < 1 and a magnitude limit i(AB)< 22. The precise photo-zs and the luminosity coverage of PAUS enable robust IA measurements, which are key for setting informative priors for upcoming stage-IV surveys. For red galaxies, we detect an increase in IA amplitude with both luminosity and stellar mass, extending previous results towards fainter and less massive regimes. As a function of redshift, we observe strong IA signals at intermediate (z(b) similar to 0.55) and high (z(b) similar to 0.75) redshift bins. However, we find no significant trend of IA evolution with redshift after accounting for the varying luminosities across redshift bins, consistent with the literature. For blue galaxies, no significant IA signal is detected, with A(1)=0.68(-0.51)(+0.53) when splitting only by galaxy colour, yielding some of the tightest constraints to date for the blue population and constraining a regime of very faint and low-mass galaxies.
