The recent DESI Baryon Acoustic Oscillation measurements have led to tight upper limits on the neutrino mass sum, potentially in tension with oscillation constraints requiring ∑ mν ≳ 0.06 eV. Under the physically motivated assumption of positive ∑ mν , we study the extent to which these limits are tightened by adding other available cosmological probes, and robustly quantify the preference for the normal mass ordering over the inverted one, as well as the tension between cosmological and terrestrial data. Combining DESI data with Cosmic Microwave Background measurements and several late-time background probes, the tightest 2σ limit we find without including a local H 0 prior is ∑ mν < 0.05 eV. This leads to a strong preference for the normal ordering, with Bayes factor relative to the inverted one of 46.5. Depending on the dataset combination and tension metric adopted, we quantify the tension between cosmological and terrestrial observations as ranging between 2.5σ and 5σ. These results are strenghtened when allowing for a time-varying dark energy component with equation of state lying in the physically motivated non-phantom regime, w(z) ≥ -1, highlighting an interesting synergy between the nature of dark energy and laboratory probes of the mass ordering. If these tensions persist and cannot be attributed to systematics, either or both standard neutrino (particle) physics or the underlying cosmological model will have to be questioned.
Abstract The National Science Foundation’s LIGO, with Virgo and KAGRA, were designed to succeed in launching the new epoch of gravitational-wave astronomy, on a ‘best effort’ basis. The next generation of terrestrial observatories, exemplified here by Cosmic Explorer (CE), can take a more structured approach to observatory and initial instrument design. For CE, priorities are to enable an initial reach some 10x greater for neutron-star coalescence while managing cost and risk. The US National Science Foundation is supporting both design and experimental activities, complemented by work in the UK, Germany, Australia, and Canada.
Velocity is a key parameter in geophysics, particularly in near-surface studies, where subsur face structures are shaped by complex geological processes. Accurate modeling of such struc tures is critical for imaging deeper formations and improving subsurface interpretations. Modern data acquisition techniques, such as digital geological outcrops and micro-logging, provide valuable structural information that enhances the accuracy of near-surface velocity models. Traveltime tomography has long been a widely used approach for near-surface ve locity modeling. However, its application is often constrained by challenges surrounding the management of complex grid configurations and the nonlinear nature of inversion, particu larly when integrating datasets of varying types, scales, and resolutions. Physics-informed neural networks (PINNs) have recently emerged as a promising solution to these challenges. Nevertheless, the inherent underdetermination in inversion means that these methods con tinue to suffer from issues with non-uniqueness and limited resolution, rendering them insufficient for near-surface modeling. To address these challenges, a novel method: the Multi-Geophysical Information Neural Network for Seismic Tomography (MINN-tomo) is proposed. This approach directly incorporates diverse datasets into the loss function, pro viding a unified framework upon which to handle data fusion across different scales during nonlinear inversion. Considering data acquisition for the near surface, geological outcrops and micro-logging are incorporated to ensure spatial continuity and improve the velocity resolution, enhancing the accuracy of the near-surface velocity model. The flexibility and efficiency of MINN-tomo is verified using four representative synthetic models: one fea turing significant near-surface characteristics, one based on the rugged seabed topography of the South China Sea, one derived from the near-surface segment of the Foothill model, and the standard Marmousi model, and the impact of key parameters within the developed framework is evaluated, highlighting its robustness and adaptability
Dark radiation (DR) is ubiquitous in physics beyond the Standard Model (SM), and its interactions with the SM and dark matter (DM) lead to a variety of interesting effects on cosmological observables. However, even in scenarios where DR is `secluded', i.e., only gravitationally interacting with SM and DM, it can leave discernible signatures. We present a comprehensive study of four different types of DR: free-streaming, self-interacting (coupled), decoupling, and recoupling DR, and vary initial conditions to include both adiabatic and isocurvature perturbations. In addition to these properties, we also vary neutrino energy density, DR energy density, and the SM neutrino masses to perform a general analysis and study degeneracies among neutrino and DR properties. We derive constraints using the cosmic microwave background, large-scale structure, and supernova datasets. We find no significant preference for physics beyond the ΛCDM model, but data exhibit interesting interplays between different physical quantities. When the neutrino energy density is allowed to vary, we find that the cosmological dataset prefers massless free-streaming DR over massive neutrinos, leading to a significant relaxation of the neutrino mass bound. For some cases, we find indications for a non-zero DR isocurvature at small scales, although below 2σ. Our analysis also highlights the degeneracy of various DR parameters with the Hubble constant H 0, resulting in a mild relaxation of the H 0 tension.
Gravitational waves (GWs) originating from cosmological sources offer direct insights into the physics of the primordial Universe, the fundamental nature of gravity, and the cosmic expansion of the Universe. In this review paper, we present a comprehensive overview of our recent advances in GW cosmology, supported by the national key research and development program of China, focusing on cosmological GW sources and their implications for fundamental physics and cosmology. We first discuss the generation mechanisms and characteristics of stochastic gravitational wave backgrounds generated by physical processes that occurred in the early Universe, including those from inflation, phase transitions, and topological defects, and summarize current and possible future constraints from pulsar timing arrays and space-based detectors. Next, we explore the formation and observational prospects of primordial black holes as GW sources and their potential connection to dark matter. We then analyze how GWs are affected by large-scale structure, cosmological perturbations, and possible modifications of gravity on GW propagation, and how these effects can be used to test fundamental symmetry of gravity. Finally, we discuss the application of GW standard sirens in measuring the Hubble constant, the expansion history, and dark energy parameters, including their combination with electromagnetic observations. These topics together show how GW observations, especially with upcoming space-based detectors, such as LISA, Taiji, and TianQin, can provide new information about the physics of the early Universe, cosmological evolution, and the nature of gravity.
We investigate potential deviations from the standard adiabatic evolution of the cosmic microwave background (CMB) temperature, $T_{\rm CMB}(z)$, using the latest Sunyaev-Zeldovich (SZ) effect measurements and molecular line excitation data, covering a combined redshift range of $03$ yield broader uncertainties. By combining both datasets, we find good consistency with the standard evolution across the full analysed redshift range, inferring a present-day CMB monopole temperature of $T_0 = 2.744 \pm 0.019$ K. Next, we test for deviations from the standard scaling by adopting the parameterisation $T_{\rm CMB}(z) = T_0(1+z)^{1-\beta}$, where $\beta$ quantifies departures from adiabaticity, with $\beta = 0$ corresponding to the standard scenario. In this framework, we use Gaussian Process reconstruction to test the consistency of $\beta = 0$ across the full redshift range and perform $\chi^2$ minimisation techniques to determine the best-fit values of $T_0$ and $\beta$. In both cases, we find good consistency with the standard temperature-redshift relation. The $\chi^2$-minimisation analysis yields best-fit values of $\beta = -0.0106 \pm 0.0124$ and $T_0 = 2.7276 \pm 0.0095$ K, in excellent agreement with both $\beta = 0$ and independent direct measurements of $T_0$ from FIRAS and ARCADE. We discuss the implications of our findings, which offer strong empirical support for the standard cosmological prediction and place tight constraints on a wide range of alternative scenarios of interest in the context of cosmological tensions and fundamental physics.
LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission focused on primordial cosmology and fundamental physics. In this paper, we present the LiteBIRD Simulation Framework (LBS), a Python package designed for the implementation of pipelines that model the outputs of the data acquisition process from the three instruments on the LiteBIRD spacecraft: LFT (Low-Frequency Telescope), MFT (Mid-Frequency Telescope), and HFT (High-Frequency Telescope). LBS provides several modules to simulate the scanning strategy of the telescopes, the measurement of realistic polarized radiation coming from the sky (including the Cosmic Microwave Background itself, the Solar and Kinematic dipole, and the diffuse foregrounds emitted by the Galaxy), the generation of instrumental noise and the effect of systematic errors, like pointing wobbling, non-idealities in the Half-Wave Plate, et cetera. Additionally, we present the implementation of a simple but complete pipeline that showcases the main features of LBS. We also discuss how we ensured that LBS lets people develop pipelines whose results are accurate and reproducible. A full end-to-end pipeline has been developed using LBS to characterize the scientific performance of the LiteBIRD experiment. This pipeline and the results of the first simulation run are presented in Puglisi et al. (2025).
Correlators of large-scale fluctuations produced during cosmic inflation are major observables of inflationary cosmology. In cosmological collider physics, many interesting correlators are generated through loop processes. However, ultraviolet divergences often appear when computing the loop correlators, and a regularization is required. In this work, Källén-Lehmann representation and dimensional regularization are used to analytically compute various correlators with a bubble loop of massive bulk propagators in de Sitter spacetime. Examples include 4-point and 2-point correlators with 1-loop bubbe exchanges of derivatively coupled massive scalars or massive spin-1 bosons.
The next generation of cosmic and gamma ray experiments plans to answer persisting fundamental questions in ultra-high-energy astroparticle physics: what sources and acceleration mechanisms can produce the most energetic particles ever measured, with energies greater than 10 EeV? Are there any photons produced in our galaxy at 10 PeV? A proposed measurement technique for next generation air-shower arrays is the layered water Cherenkov detector. The water volume is optically separated such that a majority of the electromagnetic component of the air shower will attenuate in the top part, while the bottom one measures mostly muons. Currently, at the Pierre Auger Observatory in Malargüe, Argentina, two prototypes are deployed and have been taking data for over 10 years. The calibrated signals from these detectors can be used to extract the muonic and electromagnetic signals on an event-by-event basis, allowing for a direct estimation of the muonic component and a muon-independent air-shower energy reconstruction. We present the calibration method and the next steps to assess the layered detectors’ sensitivity towards a mass-composition measurement for an extremely large array, like the Global Cosmic Ray Observatory (GCOS), or measurements of ultra-high-energy gamma rays with the Probing Extreme PeVatron Sources (PEPS) experiment.
In this study, we explore the impact of the interacting parameter on dark matter in a model resulting from a parametrization of dark energy density. To ensure a model-independent approach, we treat \( r_d \) as a free parameter, avoiding assumptions about the physics of the early Universe or specific recombination models. This approach allows late-time cosmological observations to directly constrain \( r_d \) along with other parameters. Using recent measurements from the Dark Energy Spectroscopic Instrument (DESI) Year 1, cosmic chronometers (CC) and Pantheon\(^{+}\) supernova (SNe Ia) data, we uncover a significant effect of the interacting parameter on dark matter. Our analysis reveals that while non-interacting models attribute 68.2\% of the cosmic energy density to dark energy, interacting models increase this share to 73.4\%. To further probe these differences, we evaluate the evolution of the deceleration parameter for each model, contrasting them against the \(\Lambda\)CDM paradigm and observational data from CC and SNe Ia measurements. Finally, we apply various statistical metrics to rigorously assess the performance of these models.
Abstract The mining of No.3 coal at Sihe Mine has created a large area of goaf, which has led to a large-scale pressure relief of No.15 coal. It has the advantageous conditions for the development of coalbed methane (CBM). To better achieve the efficient development of CBM, the hydraulic fracturing effect and permeability enhancement mechanism of underlying coal seams in Goaf (UCSG) were studied. This study takes the No. 15 coal of Sihe Mine as the research object. Through experiments, the seepage characteristics of coal samples in different areas after hydraulic fracturing along with gas pressure decline were obtained, and a gas pressure decline permeability model was established. A numerical simulation method for hydraulic fracturing of UCSG has been constructed. A large-scale three-dimensional numerical model was established to obtain the stress distribution law of UCSG. Based on this, a small-scale hydrostatic fracturing fluid–structure coupling numerical model of the No.15 coal was constructed. After conducting the hydraulic fracturing simulation, three areas with different degrees of permeability enhancement were delineated: the strongly disturbed area, the weakly disturbed area, and the undisturbed area. Finally, the permeability is updated based on the gas pressure decline permeability model to achieve the simulation of gas extraction. According to the simulation results, the stronger the stress concentration effect of the UCSG, the worse the hydraulic fracturing effect is. The research provides guidance for the hydraulic fracturing and gas extraction of UCSG.
Abstract Hydration of the subduction zone forearc mantle wedge influences the downdip distribution of seismicity, the availability of fluids for arc magmatism, and Earth's long term water cycle. Reconstructions of present‐day subduction zone thermal structures using time‐invariant geodynamic models indicate relatively minor hydration, in contrast to many geophysical and geologic observations. We pair a dynamic, time‐evolving thermal model of subduction with phase equilibria modeling to investigate how variations in slab and forearc temperatures from subduction infancy through to maturity contribute to mantle wedge hydration. We find that thermal state during the intermediate period of subduction, as the slab freely descends through the upper mantle, promotes extensive forearc wedge hydration. In contrast, during early subduction the forearc is too hot to stabilize hydrous minerals in the mantle wedge, while during mature subduction, slab dehydration dominantly occurs beyond forearc depths. In our models, maximum wedge hydration during the intermediate phase is 60%–70% and falls to 20%–40% as quasi‐steady state conditions are approached during maturity. Comparison to global forearc H2O capacities reveals that consideration of thermal evolution leads to an order of magnitude increase in estimates for current extents of wedge hydration and provides better agreement with geophysical observations. This suggests that hydration of the forearc mantle wedge represents a potential vast reservoir of H2O, on the order of 3.4–5.9 × 1021 g globally. These results provide novel insights into the subduction zone water cycle, new constraints on the mantle wedge as a fluid reservoir and are useful to better understand geologic processes at plate margins.
Abstract Sea surface temperature anomaly (SSTA) of ocean eddies induces an anomalous air‐sea turbulent heat flux that acts to dampen SSTA. A two‐dimensional SSTA model explores the effect of air‐sea turbulent heat flux, parameterized as SSTA damping, in shaping eddy SSTA patterns. Increased SSTA damping transitions the SSTA pattern from a monopole to dipole, indicating the balance between eddy stirring of the background SST gradient and SSTA damping. The SSTA dipole pattern increases the correlation of eddy velocity and SSTA, but SSTA damping weakens the SSTA, resulting in an optimal damping rate maximizing lateral eddy surface heat transport. Globally, the SSTA damping rate increases toward the equator. In mid‐latitude and high‐latitude regions (e.g., the Kuroshio, the Gulf Stream, and the Southern Ocean), eddy SSTAs are monopoles, while the tropics and subtropics exhibit dipole SSTA patterns due to higher damping rates, facilitating greater lateral eddy heat transport when the SSTA is large.
Abstract Geochemical mapping is a crucial tool that can provide valuable insights for a wide range of applications, including mineral resources prospecting, environmental impact assessment, geological process understanding, and climate change research. Despite its significance, geochemical mapping requires spatial modeling based on sparse, heterogeneous, and potentially inaccurate data sets. Moreover, the underlying geological processes are often imperfectly understood. Therefore, uncertainty quantification (UQ) is vital in geochemical mapping to ensure accurate and reliable results, ultimately facilitating well‐informed decision‐making. In this contribution, we distinguish two primary types of uncertainties: systemic and stochastic. We identify the key sources of uncertainties in geochemical mapping and review the techniques that have been employed or hold potential for uncertainty quantification, communication, visualization, and sensitivity analysis. This contribution also illustrates the general procedure of UQ in geochemical mapping by a case study of mapping geochemical anomalies associated with gold mineralization in northwestern Sichuan Province, China. We also explore potential strategies for mitigating the critical uncertainties, such as gathering more geochemical data, developing more effective models, enhancing our understanding of the geochemical dispersion process, or leveraging other thematic information or knowledge. Future research should prioritize addressing underexplored uncertainties and implementing more practical applications to validate the UQ procedure in geochemical mapping.
The influence of the Sun on the Earth’s atmosphere and climate has been a matter of hot debate for more than two centuries. In spite of the correlations found between the sunspot numbers and various atmospheric parameters, the mechanisms for such influences are not quite clear yet. Though great progress has been recently made, a major problem remains: the correlations are not stable, they may strengthen, weaken, disappear, and even change sign depending on the time period. None of the proposed so far mechanisms explains this temporal variability. The basis of all solar activity is the solar magnetic field which cyclically oscillates between its two components—poloidal and toroidal. We first briefly describe the operation of the solar dynamo transforming the poloidal field into toroidal and back, the evaluated relative variations of these two components, and their geoeffective manifestations. We pay special attention to the reconstruction of the solar irradiance as the key natural driver of climate. We point at some problems in reconstructing the long-term irradiance variations and the implications of the different irradiance composite series on the estimation of the role of the Sun in climate change. We also comment on the recent recalibration of the sunspot number as the only instrumentally measured parameter before 1874, and therefore of crucial importance for reconstructing the solar irradiance variations and their role in climate change. We summarize the main proposed mechanisms of solar influences on the atmosphere, and list some of the modelling and experimental results either confirming or questioning them. Two irradiance-driven mechanisms have been proposed. The “bottom-up” mechanism is based on the enhanced absorption of solar irradiance by the oceans in relatively cloud-free equatorial and subtropical regions, amplified by changes in the temperature gradients, circulation, and cloudiness. The “top-down” mechanism involves absorption by the stratospheric ozone of solar UV radiation whose variability is much greater than that of the visible one, and changes of large-scale circulation patterns like the stratospheric polar vortex and the tropospheric North Atlantic Oscillation. The positive phase of the tropospheric North Atlantic Oscillation indicative of a strong vortex is found to lag by a couple of years the enhanced UV in Smax. It was however shown that this positive response is not due to lagged UV effects but instead to precipitating energetic particles which also peak a couple of years after Smax. The solar wind and its transients modulate the flux of galactic cosmic rays which are the main source of ionization of the Earth’s atmosphere below ∼50 km. This modulation leads to modulation of the production of aerosols which are cloud condensation nuclei, and to modulation of cloudiness. Increased cloudiness decreases the solar irradiance reaching the low atmosphere and the Earth’s surface. Variations of the galactic cosmic rays also lead to variations of the electric currents and the ionospheric potential in the polar caps which may intensify microphysical processes in clouds and thus also cause cloudiness variations. Solar energetic particles are produced during eruptive events at the Sun. They produce reactive odd hydrogen HOx and nitrogen NOx which catalytically destroy ozone in the mesosphere and upper stratosphere—“direct effect.” NOx which are long-lived in the lack of photoionization during the polar night, can descend to lower altitudes and destroy ozone there producing a delayed “indirect effect.” In the absence of sunlight ozone absorbs longwave outgoing radiation emitted by the Earth and atmosphere. Ozone depletion associated with ionization increases leads to cooling of the polar middle atmosphere, enhancing the temperature contrast between polar and midlatitudes and, thus, the strength of the stratospheric polar vortex. Solar energetic particles are powerful but sporadic and rare events. An additional source of energetic particles are the electrons trapped in the Earth’s magnetosphere which during geomagnetic disturbances are accelerated and precipitate into the atmosphere. They are less energetic but are always present. Their effects are the same as that of the solar energetic particles: additional production of reactive HOx and NOx which destroy ozone resulting in a stronger vortex and a positive phase of the North Atlantic Oscillation. It has been shown that the reversals of the correlations between solar activity and atmospheric parameters have a periodicity of ∼60 years and are related to the evolution of the main forms of large-scale atmospheric circulation whose occurrence has a similar periodicity. The large-scale circulation forms are in turn influenced by the state of the polar vortex which can affect the troposphere-stratosphere interaction via the propagation of planetary waves. Two solar activity agents are supposed to affect the stratospheric polar vortex: spectral solar irradiance through the “top-down” mechanism, and energetic particles. Increased UV irradiance was found to lead to a negative phase of the North Atlantic Oscillation, while increased energetic particles result in a positive phase. Solar irradiance, like sunspots, is related to the solar toroidal field, and energetic particle precipitation is related to the solar poloidal field. In the course of the solar cycle the irradiance is maximum in sunspot maximum, and particle precipitation peaks strongly in the cycle’s declining phase. The solar poloidal and toroidal fields are the two faces of the solar large-scale magnetic field. They are closely connected, but because they are generated in different domains and because of the randomness involved in the generation of the poloidal field from the toroidal field, on longer time-scales their variations differ. As a result, in some periods poloidal field-related solar drivers prevail, in other periods toroidal field-related drivers prevail. These periods vary cyclically. When the poloidal field-related drivers prevail, the stratospheric polar vortex is stronger, and the correlation between solar activity and atmospheric parameters is positive. When toroidal field-related drivers prevail, the vortex is weaker and the correlations are negative.
Kelly Luis, Philipp Köhler, Christian Frankenberg
et al.
Abstract The risks harmful algal blooms (HAB) pose to aquatic ecosystems, public health, and coastal economies necessitate supplementation of current observation strategies. Herein, we explore the use of red solar induced fluorescence (SIF) from the TROPOspheric Monitoring Instrument (TROPOMI), a remote sensing measurement retrievable in variable cloud conditions, for Karenia brevis detection. Along the West Florida Shelf from 2018 to 2020, we compare red SIF with normalized fluorescence line height (nFLH) from MODIS‐Aqua, a standard remote sensing HAB indicator limited to clear sky days. A strong positive linear relationship is found between nFLH and red SIF during severe bloom conditions in 2018 (N = 33,376, r‐value = 0.79, R2 = 0.63) permitting direct comparison. Red SIF provided nearly double the amount of spatiotemporal fluorescence information than nFLH. This work presents the first application of TROPOMI's red SIF for HAB monitoring and illuminates an approach for bolstering early warning systems for HABs beyond clear sky conditions.
Abstract Yangtze River basin (YZB) experienced record‐breaking heat in the summer of 2022. Here, we focused on daytime‐nighttime compound heat waves, and used the magnitude index that considers both duration and intensity to investigate the risk of the 2022 extreme heat. The magnitude of heatwaves in 2022 was much larger than the historical average level, which was estimated as a 1‐in‐64‐year event over 1979–2014 climate. Without mitigation efforts (SSP585), the record‐breaking heat would emerge as normal during 2050s, and would affect ∼70% of land and projected population in the basin before global mean temperature change reaches 3°C. Such an emergence could be progressively delayed and impacts could be reduced under lower warming levels. The affected area would be 60% lesser at 2°C warming, and the emergence could be avoided by limiting warming to 1.5°C. Our results call for urgent mitigation efforts for reducing the risk of compound heat extremes.
The secular variation in the global geomagnetic field was analyzed in terms of the annual differences in monthly means by using the hourly mean data from 18 foreign (outside China) observatories of the World Data Center (WDC) for Geomagnetism from January 2010 to January 2020 as well as 9 observatories in the Geomagnetic Network of China from January 2015 to April 2021. In addition, according to the correlation of noisy components from the observatories, a covariance matrix was constructed based on residuals between observations and the CHAOS-7.4 model to remove external contamination. Through a comparison before and after denoising, we found that the overall average standard deviations were reduced by 29.97% in China and by 41.4% outside China. Results showed the correlation coefficient between external noise (mainly the magnetosphere ring current) and the Dst index was 0.82, and the correlation coefficient between external noise and the Ring Current (RC) index reached 0.94. A geomagnetic jerk was globally discovered around 2018.0 on the geomagnetic eastward component Y. The jerk timing in China was around 2020.0, and the earliest one was in 2018.75, whereas the timing outside China was around 2018.0, and the earliest one was in 2017.67. This 2-year lag may have been caused by the higher electrical conductivity of the deep mantle. After more data were added, this jerk event was found to occur in an orderly manner in the northern hemisphere as the longitude increased and the intensity gradually increased as well. The variations in location of the jerk center were analyzed according to the CHAOS-7.4 model. Results revealed six extreme points distributed nearby the equator. The strongest was near the equator, at 170°E, and the strength gradually decreased as it extended to the northern and southern hemispheres. Another extreme point with the opposite sign was located at the equator, at 20°W, in the south-central part of the Atlantic, and the strength gradually decreased as it extended into Europe. The covariance matrix method can be used to analyze data from the Macau Science Satellite-1 mission in the future, and this method is expected to play a positive role in modeling and separating the large-scale external field.
The emergence of a highly improbable coincidence incosmological observations speaks to a remarkably simple cosmic expansion.Compelling evidence now suggests that the Universe's gravitational horizon,coincident with the better known Hubble sphere, has a radius improbably equal tothe distance light could have travelled since the Big Bang. The confirmation ofthis unexpected result would undoubtedly herald the influence of new physics,yet appears to be unavoidable after a recent demonstration that theFriedmann-Lema\^itre-Robertson-Walker metric is valid only for the so-calledzero active mass equation of state. As it turns out, a cosmic fluid with thisproperty automatically produces the aforementioned equality, leaving littleroom for a cosmological constant. The alternative---a dynamical dark energy---wouldsuggest an extension to the standard model of particle physics, and a seriousre-evaluation of the Universe's early history.