Hasil untuk "Geophysics. Cosmic physics"

Bikash Ranjan Dinda

We introduce a new diagnostic for the null tests of dynamical dark energy alongside two other combined equivalent diagnostics. These diagnostics are useful, especially when we include anisotropic baryon acoustic oscillation (BAO) data in an analysis, to quantify the deviations from the standard ΛCDM model. We also consider another diagnostic for isotropic BAO observations. These null tests are independent of any late-time dark energy model or parametrization. With these diagnostics, we study the evidence for dynamical dark energy in light of Dark Energy Spectroscopic Instrument (DESI) 2024 data combined with cosmic microwave background (CMB) observations of the Planck 2018 mission and local H 0 measurements. We find no strong evidence for dynamical dark energy. The exclusion of the individual deviations at the effective redshift 0.51 of the DESI 2024 data makes the evidence even weaker. We get nearly similar results for other non-DESI BAO data. Both for DESI 2024 and other non-DESI BAO data, the evidence is almost independent of early-time physics. The evidence corresponding to the SHOES value of H 0 is higher than the corresponding tRGB value of H 0 for all combinations of data, but still not strong enough to reject the flat ΛCDM model.

Ying Zhao, Ce Zheng, A. Gelfan et al.

Frozen soils, including seasonally frozen ground and permafrost, are rapidly changing under a warming climate, with cascading effects on water, energy, and carbon cycles. We synthesize recent advances in the physics, observation, and modeling of frozen‐soil hydrology, emphasizing freeze–thaw dynamics, infiltration regimes and preferential flow, groundwater–permafrost interactions (including talik development and advective heat), and resulting shifts in streamflow seasonality. Progress in in situ sensing, geophysics, and remote sensing now resolves unfrozen water, freezing fronts, and active‐layer dynamics across scales, while land‐surface and tracer‐aided hydrological models increasingly represent phase change, macropore bypass, and vapor transport. Thaw‐induced activation of subsurface pathways alters recharge and baseflow, influences vegetation and biogeochemistry, and modulates greenhouse‐gas emissions. Key uncertainties persist in scaling micro‐scale processes, parameterizing ice‐impeded hydraulics, and representing abrupt thaw and wetland dynamics. We outline a tiered modeling framework, priority observations, and integration of vegetation–hydrology–carbon processes to improve projections of cold‐region water resources and climate feedbacks.

Nathaniel Craig, Daniel Green, Joel Meyers et al.

The baryon acoustic oscillation (BAO) analysis from the first year of data from the Dark Energy Spectroscopic Instrument (DESI), when combined with data from the cosmic microwave background (CMB), has placed an upper-limit on the sum of neutrino masses, ∑mν< 70 meV (95%). In addition to excluding the minimum sum associated with the inverted hierarchy, the posterior is peaked at ∑mν = 0 and is close to excluding even the minumum sum, 58 meV at 2σ. In this paper, we explore the implications of this data for cosmology and particle physics. The sum of neutrino mass is determined in cosmology from the suppression of clustering in the late universe. Allowing the clustering to be enhanced, we extended the DESI analysis to ∑mν< 0 and find ∑mν =160±90 meV (68%), and that the suppression of power from the minimum sum of neutrino masses is excluded at 99% confidence. We show this preference for negative masses makes it challenging to explain the result by a shift of cosmic parameters, such as the optical depth or matter density. We then show how a result of ∑mν = 0 could arise from new physics in the neutrino sector, including decay, cooling, and/or time-dependent masses. These models are consistent with current observations but imply new physics that is accessible in a wide range of experiments. In addition, we discuss how an apparent signal with ∑mν< 0 can arise from new long range forces in the dark sector or from a primordial trispectrum that resembles the signal of CMB lensing.

Gonzalo Herrera

NGC 1068 is the brightest extragalactic source in high-energy neutrinos as seen by IceCube, yet the accompanying gamma-ray flux is orders of magnitude weaker. It has been argued that this indicates that the bulk of neutrinos and gamma rays are emitted in the innermost vicinity of the central supermassive black hole, which is transparent to neutrinos, but opaque to gamma rays. Even in such extreme scenarios for the acceleration of cosmic rays, astrophysical models typically overestimate the low-energy gamma-ray flux and/or require some fine-tuning in the physical parameters. Here we suggest instead that the dark matter surrounding the supermassive black hole may absorb the gamma rays, inducing the observed deficit. We show that for a dark matter-photon scattering cross section in the range $\sigma_{\rm DM-\gamma}/m_{\rm DM} \simeq 10^{-28}-10^{-30}$ cm$^2$/GeV, Fermi-LAT measurements can be well reconciled with IceCube data. We also present some simple particle physics examples that achieve the correct spectral energy dependence while respecting complementary constraints.

Sebastian Bahamonde, Rebecca Briffa, K. Dialektopoulos et al.

In this paper, we study flat FLRW cosmology for a Poincar\'e gauge theory containing cubic invariants that is free from ghosts in arbitrary backgrounds in the axial and vector sectors of the torsion tensor. The new degrees of freedom can be related to hypermomentum but continue to be dynamical even in vacuum. These extra degrees of freedom open a more natural way in which to construct potential gravitational models that provide possible ways to modify astrophysical and cosmological physics. In this framework, we study two particular branches of the theory where preliminary routes of exploring these new variables are exposed. The first is the branch where the hypermomentum vanishes, while the second branch involves the setting where the perfect fluid and hypermomentum parts of the sources are independently conserved. In both settings, we find generically faster expanding cosmologies with similar estimates of the cosmic matter content as in the standard model of cosmology. Cubic Poincar\'e Gauge gravity offers an interesting theoretical basis on which to study cosmology, and indicates some preliminary positive constraints when compared with observational constraints.

F. Neukart, E. Marx, Valerii M. Vinokur

Primordial black holes (PBHs) remain one of the most intriguing candidates for dark matter and a unique probe of physics at extreme curvatures. Here, we examine their formation in a bounce cosmology when the post-crunch universe inherits a highly inhomogeneous distribution of imprint entropy from the Quantum Memory Matrix (QMM). Within QMM, every Planck-scale cell stores quantum information about infalling matter; the surviving entropy field S(x) contributes an effective dust component T (QMM) μν = λ[(∇ μS)(∇ νS)-1/2gμν (∇S)2 +…] that deepens curvature wherever S is large. We show that (i) reasonable bounce temperatures and a QMM coupling λ ∼ 𝒪(1) naturally amplify these “information wells” until the density contrast exceeds the critical value δc ≃ 0.3; (ii) the resulting PBH mass spectrum spans 10-16 M ⊙–103 M ⊙, matching current microlensing and PTA windows; and (iii) the same mechanism links PBH abundance to earlier QMM explanations of dark matter and the cosmic matter-antimatter imbalance. Observable signatures include a mild blue tilt in small-scale power, characteristic μ-distortions, and an enhanced integrated Sachs-Wolfe signal — all of which will be tested by upcoming CMB, PTA, and lensing surveys.

Itzi Aldecoa-Tamayo, Christian T. Byrnes, D. Seery

We reconsider primordial black hole physics in Randall-Sundrum Type-II universes, focusing on constraints from cosmological and astrophysical observables. We pay particular attention to scenarios that allow the entirety of dark matter to be in the form of higher-dimensional primordial black holes. This is possible for a range of AdS radii and black hole masses. Observable constraints are generally modified due to the changes in the higher-dimensional gravitational sector, and come from low-energy e ± emission, microlensing, and possibly from contributions to unresolved radiation backgrounds. We discuss constraints from the cosmic microwave background due to injection of Hawking quanta into the intergalactic medium. Finally, we comment on recent discussions on the compatibility of higher-dimensional black holes and the KM3-230213A event.

Yan-Heng Yu, Zhe Chang, Sai Wang

Dissipation is an intrinsic property of the cosmic fluid, leading to the damping of curvature perturbations at small scales. In this paper, we comprehensively study dissipative effects in gravitational waves induced by curvature perturbations, known as induced gravitational waves (IGWs). We find dissipative effects become especially significant at wavenumber k ∼ k ℋ,dec where k ℋ,dec corresponds to the horizon scale at the decoupling of weakly-interacting particles. They can leave characteristic features on the IGW spectrum, including a notable suppression with a “double-valley” structure at k ≲ k ℋ,dec and a modified infrared behavior without logarithmic running at k ≲ k_ℋ,dec. Within the Standard Model of particle physics, dissipative effects caused by neutrinos at the nanohertz frequencies can be important in the analysis of pulsar timing array data. Furthermore, dissipation-induced features associated with possible new weakly-interacting particles can be detectable by a wide range of gravitational-wave experiments, serving as a promising probe of new physics at extremely high energy scales. As an extension, we also discuss dissipative effects in the presence of primordial non-Gaussianity and their impacts on the anisotropies of IGWs and the poltergeist mechanism. These dissipative effects not only provide a more realistic description of IGWs but also exhibit rich phenomenology and profound physical implications, opening a new window into understanding the early Universe and fundamental physics.

F. Schroeder

IceCube-Gen2, the next generation extension of the IceCube Neutrino Observatory at the South Pole, offers a unique scientific potential for cosmic-ray physics at PeV to EeV energies complementing the main science case of neutrino astronomy. The cosmic-ray science case will be enabled by a surface array on top of an extended optical array deep in the polar ice. The optical array measures TeV muons of air showers, and the surface array primarily measures the electromagnetic shower component and low-energy muons. The design of the surface array foresees scintillation panels providing a full-efficiency threshold for near-vertical proton showers of 0.5 PeV and radio antennas increasing the measurement accuracy for the electromagnetic shower component in the energy range of the Galactic-to-extragalactic transition. Compared to IceCube, the aperture for air showers measured in coincidence with the surface and optical arrays will increase by a factor of 30, due to the larger area and angular acceptance in zenith angle. The science potential includes both, the particle physics of air showers, such as prompt muons, and the astrophysics of the highest energy Galactic cosmic-rays, enabled by the higher sensitivity for the mass composition and anisotropy of cosmic rays, and by the search for PeV photons. This proceeding summarizes the science case and design of the surface array as presented in the recently released IceCube-Gen2 Technical Design Report: https://icecube-gen2.wisc.edu/science/publications/tdr/

A. Whitford, C. Howlett, Tamara M. Davis et al.

Neutrinos with Standard Model interactions free-stream in the early Universe, leaving a distinct phase shift in the pattern of baryon acoustic oscillations (BAO). When isolated, this phase shift allows one to robustly infer the presence of the cosmic neutrino background in BAO and cosmic microwave background (CMB) data independently of other cosmological parameters. While in the context of the Standard Model, this phase shift follows a known scale-dependent relation, new physics in the cosmic neutrino background could alter the overall shape of this feature. In this paper, we discuss how changes in the neutrino phase shift could be used to constrain self-interactions among neutrinos. We produce simple models for this phase-shift assuming universal self-interactions, and use these in order to understand what constraining power is available for the strength of such interactions in BAO and CMB data. We find that, although challenging, it may be possible to use a detection of the phase to put a more robust limit on the strength of the self-interaction, G eff, which at present suffers from bimodality in cosmological constraints. Our forecast analysis reveals that BAO data alone will not provide the precision needed to tightly constrain self-interactions; however, the combined analysis of the phase shift signature in both CMB and BAO can potentially provide a way to detect the impact of new neutrino interactions. Our results could be extended upon for models with non-universal interactions.

Vladimir S. Netchitailo

This article represents the culmination of a decade-long effort to develop the World-Universe Cosmology (WUC), building upon a series of published works . These include the first one, "5D World-Universe Model. Space-Time-Energy" [1] and the last one, "JWST Discoveries and the Hypersphere World-Universe Model. Transformative New Cosmology" [2], both featured in the Journal of High Energy Physics, Gravitation and Cosmology. WUC is a unified model of the World built around the concept of the Cosmic Medium, composed of particles (protons, electrons, photons, neutrinos, and universe-created particles). WUC provides a mathematical framework that enables precise calculation of Medium-bound physical parameters: Gravitational parameter, Hubble’s parameter, Absolute age of the World, Intergalactic plasma parameters, Temperature of microwave background radiation and the Minimum energy of photons. This paper aligns WUC with the theoretical framework developed by P. Wesson and J. Overduin [3], [4], albeit assigning a new physical meaning to the fourth spatial coordinate associated with the total energy of the observable World.

R. Co, N. Fernandez, A. Ghalsasi et al.

Despite stringent constraints from Big Bang Nucleosynthesis (BBN) and cosmic microwave background (CMB) observations, it is still possible for well-motivated particle physics models to substantially alter the cosmic expansion history between BBN and recombination. In this work we consider two different axion models that can realize a period of first matter domination, then kination, in this epoch. We perform fits to both primordial element abundances as well as CMB data and determine that up to a decade of late axion domination is allowed by these probes of the early universe. We establish the implications of late axion domination for the matter power spectrum on the scales 1/Mpc ≲ k ≲ 103/Mpc. Our `log' model predicts a relatively modest bump-like feature together with a small suppression relative to the standard ΛCDM predictions on either side of the enhancement. Our `two-field' model predicts a larger, plateau-like feature that realizes enhancements to the matter power spectrum of up to two orders of magnitude. These features have interesting implications for structure formation at the forefront of current detection capabilities.

𝑎 T.Sako, M. Anzorena, 𝑎 E. de la Fuente et al.

: Though the maximum energy of the charged cosmic ray observations exceeds 100EeV, the energy frontier of the gamma-ray observations is PeV. In the past years, Tibet AS 𝛾 , HAWC and LHAASO opened a new window of astronomy in the sub-PeV to PeV range, which is important to unveil yet unknown PeV cosmic accelerators in our galaxy. As these 3 experiments are all located in the northern hemisphere, observations in the southern hemisphere have been awaited. Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA) is a new air shower array experiment under construction in the Bolivian Andes to explore the southern gamma-ray sky for the first time in this energy range. In this presentation, we will provide an overview of the ALPACA project, including the initial observational results from a quarter-sized array named ALPAQUITA, which has been operating since 2023. A successful detection of the shadowof the moon, for example, validates the designed performance of the array. We will also outline the plan for the full-scale construction of ALPACA.

Giulio Barni, S. Blasi, Eric Madge et al.

Cosmological first order phase transitions are a frequent phenomenon in particle physics beyond the Standard Model, and the corresponding gravitational wave signal offers a key probe of new physics in the early Universe. Depending on the underlying microphysics, the transition can exhibit either direct or inverse hydrodynamics, leading to a different phenomenology. Most studies to date have focused on direct transitions, where the cosmic fluid is pushed or dragged by the expanding vacuum bubbles. In contrast, inverse phase transitions are characterized by fluid profiles where the plasma is sucked in by the expanding bubbles. Using the sound shell model, we derive and compare the gravitational wave spectra from sound waves for direct and inverse phase transitions, providing new insights into the potential observable features and the possibility of discriminating among the various fluid solutions in gravitational wave experiments.

A. Albert, S. Alves, M. André et al.

Interest for studying cosmic neutrinos using deep-sea detectors has increase after the discovery of a diffuse flux of cosmic neutrinos by the IceCube collaboration and the possibility of wider multi-messenger studies with the observations of gravitational waves. The ANTARES detector was the first neutrino telescope in seawater, operating successfully in the Mediterranean Sea for more than a decade and a half. All challenges related to the operation in the deep sea were accurately addressed by the collaboration. Deployment and connection operations became smoother over time; data taking and constant re-calibration of the detector due to the variable environmental conditions were fully automated. A wealth of results on the subject of astroparticle physics, particle physics and multi-messenger astronomy have been obtained, despite the relative modest size of the detector, paving the way to a new generation of larger undersea detectors. This review summarizes the efforts by the ANTARES collaboration that made the possibility to operate neutrino telescopes in seawater a reality and the results obtained in this endeavor.

J. Ebr, J. Blavzek, Jakub V'icha et al.

Data from multiple experiments suggest that the current interaction models used in Monte Carlo simulations do not correctly reproduce the hadronic interactions in air showers produced by ultra-high-energy cosmic rays (UHECR). We have created a large library of UHECR simulations where the interactions at the highest energies are slightly modified in various ways - but always within the constraints of the accelerator data, without any abrupt changes with energy and without assuming any specific mechanism or dramatically new physics at the ultra-high energies. Recent results of the Pierre Auger Observatory indicate a need for a change in the prediction of the models for both the muon content at ground and the depth of the maximum of longitudinal development of the shower. In our parameter space, we find combinations of modifications that are in agreement with this analysis, however a consistent description of UHECR showers remains elusive. Our library however provides a realistic representation of the freedom in the modeling of the hadronic interactions and offers an opportunity to quantify uncertainties of various predictions. This can be particularly valuable for the design of future observatories where hadronic models are often used as input for the prediction of the performance. We demonstrate this powerful capability on several selected examples.

Liang Chang, Hu Jiang, Jiji Cai

Dark Matter Particle Explorer (short for DAMPE) is one of the space missions innovated by the Chinese Academy of Sciences. Its scientific goals are to discover dark matter particles, study the characteristics of dark matter particles and their laws of space deployment, detect gamma rays, and find out the source’s cosmic rays. The attainment of such goals will lead to great leaps in the frontiers of modern physics and astronomy. Based on precision orbit elements of DAMPE newly available, some main orbit elements were simulated. Further, with the help of SOCRATES Plus software, the close approach of DAMPE to the space objects was computed. The objects are singled out that may endanger the wholesomeness of the DAMPE.

Zhiyuan Yu, Zhen-Hao Yang, Taotao Qiu

The latest observational data of the Planck satellite show a nontrivial value of polarization rotation angle caused by cosmic birefringence in the early universe. Moreover, the asymmetry of baryons versus anti-baryons still remains mysterious. Both of them indicate that there should be hidden new physics, such as fundamental symmetry breaking. In this paper, we try to interpret these two events in the framework of nonmetricity modified gravity. We introduce an interaction term between the nonmetricity-based function and matter current, and calculate both the rotation angle and baryon-to-photon ratio. We also constrain the model parameters using the current observational data. With some specific examples, we demonstrate that in nonmetric gravity theory, these two events can be interpreted in a unified way. Nevertheless, in this case, the minimal coupling of the nonmetricity scalar and the matter current might not be favored.

A. Ivanova, M. N. Lopatin, I. Astapov et al.

Jan I. H. Askne

The Copernicus DEM is derived as a mean of TanDEM-X phase heights. It is known that there is an almost linear&#x2014;but variable&#x2014;relationship between phase height and above-ground biomass (AGB). This article investigates the relationship between the mean of TanDEM-X phase heights and AGB. The slope between TanDEM-X phase height and AGB varies across different acquisitions from the same site, influenced by meteorological conditions and the height of ambiguity (HoA), which is the height corresponding to a 2&#x03C0; phase shift. An expression based on the Interferometric Water Cloud Model (IWCM) is introduced to represent an average of meteorological variations. This approach uses an ICESat-based method to describe the relationship between area-fill (canopy cover) and forest height. The product of density and height is shown to be approximately linear with AGB under certain conditions. This enables us to express mean phase height as a function of AGB, provided that either the AGB-height allometry or reference AGB values from field data are known. The results demonstrate a strong resemblance and near-linear relationship between mean phase height, mean forest height, and AGB across a wide range of conditions. The analysis is illustrated with 32 TanDEM-X acquisitions from the Remningstorp and Krycklan sites. Forest height and area-fill are estimated from mean phase height, and AGB is also derived for these sites.