The grand challenges of contemporary fundamental physics—dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem—all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on ‘Black holes, Gravitational waves and Fundamental Physics’.
Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With a strain sensitivity of $10^{-23}/\sqrt{\mathrm{Hz}}$ at 100 Hz, the product of observable volume and measurement time exceeded that of all previous runs within the first 16 days of coincident observation. On September 14th, 2015 the Advanced LIGO detectors observed a transient gravitational-wave signal determined to be the coalescence of two black holes [Phys. Rev. Lett. 116, 061102 (2016)], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 in coincidence by the two detectors. Here we present the main features of the detectors that enabled this observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver another factor of three improvement in the signal-to-noise ratio for binary black hole systems similar in masses to GW150914.
The James Webb Space Telescope, or JWST, or simply Webb, is a large, space-based observatory, designed primarily to conduct infrared astronomy. The telescope is named after James Edwin Webb (1906–1992), who was the second administrator of NASA during 1961–1968. It is an advanced next-generation telescope that will complement and extend the discoveries of the Hubble Space Telescope. The JWST has been developed by the National Aeronautics and Space Administration (NASA) of the United States of America in collaboration with the European Space Agency (ESA) and the Canadian Space Agency (CSA). It took over 24 years to place the Webb on the launch pad. The Webb was launched on 25 December 2021 at 7:20 AM (12:20 UTC) onboard ESA’s Ariane 5 rocket from Kourou, French Guiana.
Low-rate Denial-of-Service (LDoS) attacks exploit periodic traffic pulses to trigger congestion while maintaining a low average rate, making them highly stealthy and difficult to distinguish from legitimate bursty traffic using threshold-based or simple statistical detectors. To address this challenge, this paper proposes DELP-Net, an end-to-end Differentiable Entropy Layer Pyramid Network for window-level online LDoS detection directly from raw traffic. DELP-Net combines a multi-scale one-dimensional convolutional pyramid with a differentiable Rényi-entropy-driven attention mechanism to capture distributional regularity and weak repetitive patterns characteristic of LDoS traffic. In addition, an entropy-conditioned temporal convolutional network is employed to model cross-window periodic dependencies in a lightweight manner, together with an entropy-regularized hybrid loss to enhance robustness under complex background traffic. Experiments on the low-rate DoS dataset show that DELP-Net achieves an average F1 score of 0.9877 across six LDoS attack types, with a detection rate of 98.69% and a false-positive rate of 1.15%, demonstrating its effectiveness and suitability for practical online intrusion detection deployments.
With the increasing importance of securing images during network transmission, this paper introduces a novel image encryption algorithm that integrates a 3D chaotic system with V-shaped scrambling techniques. The proposed method begins by constructing a unique 3D chaotic system to generate chaotic sequences for encryption. These sequences determine a random starting point for V-shaped scrambling, which facilitates the transformation of image pixels into quaternary numbers. Subsequently, four innovative bit-level scrambling strategies are employed to enhance encryption strength. To further improve randomness, DNA encoding is applied to both the image and chaotic sequences, with chaotic sequences directing crossover and DNA operations. Ciphertext feedback is then utilized to propagate changes across the image, ensuring increased complexity and security. Extensive simulation experiments validate the algorithm’s robust encryption performance for grayscale images, yielding uniformly distributed histograms, near-zero correlation values, and an information entropy value of 7.9975, approaching the ideal threshold. The algorithm also features a large key space, providing robust protection against brute force attacks while effectively resisting statistical, differential, noise, and cropping attacks. These results affirm the algorithm’s reliability and security for image communication and transmission.
M. A. Cafolla, S. C. Chapman, N. W. Watkins
et al.
Abstract Total Electron Content (TEC) is central to characterizing ionospheric response to solar and geomagnetic activity. Variations in TEC structures over time provide insight into underlying physical processes and inform monitoring of space weather events, which pose a risk to navigation and communication systems. JPL processed GNSS observations over 20 years provide a series of 15‐min Global Ionospheric Maps (GIMs) of spatial resolution 1°×1° longitude/latitude. We translate these into geomagnetic coordinates centered about the sub‐solar point and we isolate the top 1% of TEC values in each map to define High Density Regions (HDRs) of TEC. Image processing tools are used to develop an algorithm that detects and tracks these to compile a set of contiguous, uniquely labeled space‐time TEC HDRs. We find that HDRs naturally divide into two populations by peak area, separated by a size of 8.0×106km2, which is around the continental scale. These populations are studied for different storm conditions—quiet (Kp <4), moderate (4≤ Kp <7) and extreme (Kp ≥7): small HDRs form primarily around four magnetic latitude bands and move roughly parallel to lines of constant magnetic latitude toward later MLT. Large HDRs form around the same latitude bands but follow more complex paths. The statistical nature of these results could be used in predictive ionospheric models and identify reproducible trends on these spatial/temporal scales.
Abstract Geomagnetic storms produce global variations in the geomagnetic field that are measured at magnetic observatories. Roughly one half of magnetic storms are preceded by sudden increases in the horizontal component of the magnetic field world‐wide. These increases, called storm sudden commencements (SSC), produce geomagnetically induced currents and cause other space weather disturbances whose study is paramount due to the technological dependence of our society. SSC event lists date back to 1868 and provide invaluable information about interplanetary conditions over centennial time scales. Since 1975, the Service of Rapid Magnetic Variations has been responsible for the maintenance and consistency of the SSC list. Here we will review the significant changes in the definition and methods of SSC detection that have been introduced over time and will analyze and discuss whether those changes have affected the homogeneity of the SSC series. Alerted by the greatly reduced number of SSCs in solar cycle 24, we have reanalyzed SSC occurrence in the period 2006–2017. As a result, we found a 26% increase in the number of SSCs, which motivates a change in the adopted SSC definition but leaves the SSC level exceptionally low during this period. We completed the study by examining the relation and dependency of SSCs with solar sunspot numbers and the temporal variation of the horizontal magnetic field.
Zi-Li Yue, Cheng-Jian Xiao, H. García-Tecocoatzi
et al.
Abstract Inspired by the abundant structure near the threshold of the $$D^{(*)}K^{(*)}/\bar{D}^{(*)}K^{(*)},$$ D ( ∗ ) K ( ∗ ) / D ¯ ( ∗ ) K ( ∗ ) , we estimate the strong decay properties of the $$T_{c\bar{s}1}^{f/a}$$ T c s ¯ 1 f / a and $$T_{\bar{c}\bar{s}1}^{f/a}$$ T c ¯ s ¯ 1 f / a with $$I(J^{P})=0/1(1^{+})$$ I ( J P ) = 0 / 1 ( 1 + ) in $$DK^{*}$$ D K ∗ and $$\bar{D}K^{*}$$ D ¯ K ∗ molecular scenarios in the present paper. By employing the effective Lagrangian approach, the widths of the processes $$T_{c\bar{s}1}^{f}\rightarrow D^{*}K, D_{s}^{*}\eta , DK\pi ,$$ T c s ¯ 1 f → D ∗ K , D s ∗ η , D K π , $$T_{c\bar{s}1}^{a}\rightarrow D^{*}K, D_{s}^{*}\pi , DK\pi ,$$ T c s ¯ 1 a → D ∗ K , D s ∗ π , D K π , and $$T_{\bar{c}\bar{s}1}^{f/a}\rightarrow \bar{D}^{*}K, \bar{D}K\pi $$ T c ¯ s ¯ 1 f / a → D ¯ ∗ K , D ¯ K π are estimated. Considering the present estimations, we propose to search for $$T_{c\bar{s}1}^{f/a}$$ T c s ¯ 1 f / a states in $$D^{*}K$$ D ∗ K and $$D_{s}^{*}\pi /D_{s}^{*}\eta $$ D s ∗ π / D s ∗ η mass invariant spectra. Their ratios may serve as an important test of the molecular scenario.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Kiyoaki Doi, Akimasa Kataoka, Hauyu Baobab Liu
et al.
The PDS 70 system, hosting two planets within its disk, is an ideal target for examining the effect of planets on dust accumulation, growth, and ongoing planet formation. Here, we present high-resolution (0.″07 = 8 au) dust continuum observations of the PDS 70 disk in ALMA Band 3 (3.0 mm). While previous Band 7 observations showed a dust ring with slight asymmetry, our Band 3 observations reveal a more prominent asymmetric peak in the northwest direction, where the intensity is 2.5 times higher than in other directions and the spectral index is at the local minimum with α _SED ∼ 2.2. This indicates that a substantial amount of dust is accumulated both radially and azimuthally in the peak. We also detect point-source emission around the stellar position in the Band 3 image, which is likely to be free–free emission. We constrain the eccentricity of the outer ring to be e < 0.04 from the position of the central star and the outer ring. From the comparison with numerical simulations, we constrain the mass of PDS 70c to be less than 4.9 ${M}_{{\rm{Jupiter}}}$ if the gas turbulence strength α _turb = 10 ^−3 . Then, we discuss the formation mechanism of the disk structures and further planet formation scenarios in the disk.
Abstract General expressions for one-loop contributions associated with lepton-flavor violating decays of the standard model-like Higgs boson $$h\rightarrow e_b^\pm e_a^\mp $$ h → e b ± e a ∓ and gauge boson $$Z\rightarrow e^\pm _b e_a^\mp $$ Z → e b ± e a ∓ are introduced in the unitary gauge. The results are used to discuss these decays as new physics signals in a minimal left-right symmetric model containing only one bidoublet Higgs and a $$SU(2)_R$$ S U ( 2 ) R Higgs doublet accommodating data of neutrino oscillations and $$(g-2)_{\mu }$$ ( g - 2 ) μ . The numerical investigation indicates that some of these decay rates can reach near future experimental sensitivities.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
We present a general procedure for deriving a line-profile model for massive-star X-ray spectra that captures the dynamics of the wind more directly. The basis of the model is the analytic solution to the problem of variable jets in Herbig–Haro objects given by Cantó et al. In deriving our model, we generalize this jet solution to include flows with a prescribed nonzero acceleration for the context of radiatively driven winds. We provide example line profiles generated from our model for the case of sinusoidal velocity and mass-ejection variations. The example profiles show the expected shape of massive-star X-ray emission lines, as well as interesting but complicated trends with the model parameters. This establishes the possibility that observed X-rays could be a result of temporal variations seeded at the wind base, rather than purely generated intrinsically within the wind volume, and can be described via a quantitative language that connects with the physical attributes of those variations, consistently with the downstream momentum-conserving nature of radiatively cooled shocked radial flows.
F. A. Barone, L. H. C. Borges, G. Flores-Hidalgo
et al.
Abstract In this paper we propose a coupling between the complex scalar field and an external Dirac delta-like planar potential. The coupling is achieved through the Klein–Gordon current normal to the plane where the potential is concentrated. The results are obtained exactly and exhibit many peculiarities. We show that a complex scalar charge does not interact with the potential, but the potential modifies the interaction between two scalar charges if they are placed on opposite sides of the planar potential. When the coupling constant between the potential and the field goes to infinity, the classical field solutions satisfy a kind of MIT boundary conditions along the plane where the potential is concentrated.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Active regions are the brightest structures seen in the solar corona, so their physical properties hold important clues to the physical mechanisms underlying coronal heating. In this work, we present a comprehensive study for a filament-embedding active region as determined from observations from multiple facilities including the Chinese H α Solar Explorer. We find three types of dynamic features that correspond to different thermal and magnetic properties, i.e., the overlying loops—1 MK cool loops, the moss region—2–3 MK hot loops’ footprints, and the sigmoidal filament. The overlying cool loops, which have a potential field, always show Doppler blueshifts at the east footprint and Doppler redshifts at the west, indicating a pattern of “siphon flow.” The moss-brightening regions, which sustain the hot loops that have a moderate sheared field, always show downward Doppler redshifts at the chromosphere, which could be a signature of plasma condensing into the inner region adjacent to the filament. The sigmoidal filament, which has strongly sheared field lines along the polarity inversion line, however, shows a different Doppler velocity pattern in its middle part, i.e., an upward Doppler blueshift at the double- J -shaped stage indicating tether-cutting reconnection during the filament channel formation and then a downward redshift showing the plasma condensation for the sigmoidal filament formation. The present work shows overall properties of the filament-embedding active region, constraining the heating mechanisms of different parts of the active region and providing hints regarding the mass loading of the embedded filament.
Abstract In a large class of nonlocal as well as local higher derivative theories minimally coupled to the matter sector, we investigate the exactness of two different classes of homogeneous Gödel-type solutions, which may or may not allow closed time-like curves (CTC). Our analysis is limited to spacetimes solving the Einstein’s EoM, thus we can not exclude the presence of other Gödel-type solutions solving the EoM of local and nonlocal higher derivative theories but not the Einstein’s EoM. It turns out that the homogeneous Gödel spacetimes without CTC are basically exact solutions for all theories, while the metrics with CTC are not exact solutions of (super-)renormalizable local or nonlocal gravitational theories. Hence, the quantum renormalizability property excludes theories suffering of the Gödel’s causality violation. We also comment about nonlocal gravity non-minimally coupled to matter. In this class of theories, all the Gödel’s spacetimes, with or without CTC, are exact solutions at classical level. However, the quantum corrections, although perturbative, very likely spoil the exactness of such solutions. Therefore, we can state that the Gödel’s Universes with CTC and the super-renormalizability are mutually exclusive.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Abstract Several new physics scenarios that address anomalies in B-physics predict an enhancement of $$b \rightarrow s \tau \tau $$ b → s τ τ with respect to its Standard Model prediction. Such scenarios necessarily imply modifications of the lifetime ratio $$\tau _{B_{s}}/\tau _{B_{d}}$$ τ B s / τ B d and the lifetime difference $$\Delta \Gamma _{s}$$ Δ Γ s . In this work, we explore indirect bounds provided by these observables over new physics scenarios. We also estimate future projections, showing that future experimental and theoretical improvements on both $$\tau _{B_{s}}/\tau _{B_{d}}$$ τ B s / τ B d and $$\Delta \Gamma _{s}$$ Δ Γ s have the potential to provide bounds competitive with those directly extracted from $$b\rightarrow s \tau \tau $$ b → s τ τ transitions. After performing a model-independent analysis, we apply our results to the particular case of leptoquark mediators proposed to address the $$R_{D^{(*)}}$$ R D ( ∗ ) anomalies.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
It is intriguing but challenging to control the complex dynamics of topological defects that emerge in nonequilibrium spatiotemporal systems. Through an effective modelling this work explores a viable way to controllably vary the properties of persistent defect dynamics in self-propelled active smectics via the competition of activity and boundary confinements with different topology and geometry.