We study the dynamical excitation of quasinormal modes (QNMs) through the plunge, merger and ringdown of an extreme-mass-ratio-inspiral into a Schwarzschild black hole, for generic orbital configurations. We work out the QNM causality condition, crucial to eliminate amplitude divergences and to incorporate horizon redshift effects. We then use it to derive a model of the time-dependent QNM excitation via a Green’s function approach, driven by the point-particle source on a given trajectory. Our model predicts that: (i) QNMs propagates along hyperboloidal slices in the minimal gauge; (ii) the signal is composed of an “activation” term, depending on the source past history, and a local “impulsive” term; (iii) amplitudes grow in time in an “activation function” fashion, and the waveform displays a stationary ringdown regime at times $\sim 10–20M$ after its peak; (iv) at these late times, an infinite tower of nonoscillatory, exponentially damped terms appear: the redshift terms. The model is in good agreement with numerical solutions, capturing the main waveform features after the peak. Additional components of the Green’s function are required to complement the QNM description and reproduce the plunge-merger waveform. We predict the late-time, stationary amplitude of the quadrupolar mode as a function of eccentricity, in agreement with accurate numerical solutions, marking the first time that QNM amplitudes are predicted for generic binary configurations. Our work provides a first solid step toward analytically modeling the inspiral’s imprint onto ringdown signals, generalizable to include higher orders in the mass ratio, black hole spin, nonvacuum configurations and corrections to the Einstein-Hilbert action.

The second data release (DR2) of the Dark Energy Spectroscopic Instrument (DESI), containing data from the first three years of observations, doubles the number of Lyman-$\alpha$ ($\mathrm{Ly}\alpha$) forest spectra in DR1 and it provides the largest dataset of its kind. To ensure a robust validation of the baryonic acoustic oscillation (BAO) analysis using $\mathrm{Ly}\alpha$ forests, we have made significant updates compared to DR1 to both the mocks and the analysis framework used in the validation. In particular, we present CoLoRe-QL, a new set of $\mathrm{Ly}\alpha$ mocks that use a quasilinear input power spectrum to incorporate the nonlinear broadening of the BAO peak. We have also increased the number of realizations used in the validation to 400, compared to the 150 realizations used in DR1. Finally, we present a detailed study of the impact of quasar redshift errors on the BAO measurement, and we compare different strategies to mask damped Lyman-$\alpha$ absorbers in our spectra. The BAO measurement from the $\mathrm{Ly}\alpha$ dataset of DESI DR2 is presented in a companion publication.

In this work, we explore the range of validity of the semiclassical approximation of a quantum master equation designed to describe the $c\overline{c}$ dynamics in a quark-gluon plasma at various temperatures, in the quantum Brownian regime. We perform a comparative study of various properties, e.g., the charmonia yield, of the Wigner density obtained both with the Lindblad equation and with the associated semiclassical Fokker-Planck equation. The semiclassical description is found to reproduce with a remarkable accuracy the results obtained through the full quantum description. We show that, to a large extent, this can be attributed to the nonunitary components of the dynamics that result from the contact of the $c\overline{c}$ subsystem with the thermal quark-gluon bath, leading to a rapid classicalization of the subsystem.

Gravitational waves propagating across gravitational potentials undergo lensing effects that, in the wave-optics regime, manifest as frequency-dependent amplitude and phase modulations. In this work, we revisit the diffraction integral formalism of gravitational lensing and demonstrate that it admits a natural and transparent interpretation within the framework of scattering theory. We establish a direct correspondence between the lensing amplification factor and the scattering amplitude of waves propagating in curved spacetime, clarifying how familiar lensing limits map onto distinct scattering regimes. In particular, we show that the diffraction integral matches exactly the eikonal limit of the scattering amplitude at lowest post-Minkowskian order, after a change in coordinates and the inclusion of finite-distance effects. We further extend the standard formalism by including subleading corrections to the post-Minkowskian and eikonal approximations. Our results provide a unified theoretical framework for the interpretation of lensed gravitational-wave signals and open the way to more accurate waveform modeling for future lensed observations.

Neutrinos are produced during stellar evolution by means of thermal and thermonuclear processes. We model the cumulative neutrino flux expected at Earth from all stars in the Milky Way: the Galactic stellar neutrino flux ($\mathrm{GS}\nu \mathrm{F}$). We account for the star formation history of our Galaxy and reconstruct the spatial distribution of Galactic stars by means of a random sampling procedure based on Gaia Data Release 2. We use the stellar evolution code mesa to compute the neutrino emission for a suite of stellar models with solar metallicity and zero-age-main-sequence mass between $0.08M_{\odot }$ and $100M_{\odot }$, from their premain sequence phase to their final fates. We then reconstruct the evolution of the neutrino spectral energy distribution for each stellar model in our suite. The $\mathrm{GS}\nu \mathrm{F}$ lies between $\mathcal{O}(1)\mathrm{keV}$ and $\mathcal{O}(10)\mathrm{MeV}$, with thermal (thermonuclear) processes responsible for shaping neutrino emission at energies smaller (larger) than 0.1 MeV. Stars with mass larger than $\mathcal{O}(1M_{\odot })$, located in the thin disk of the Galaxy, provide the largest contribution to the $\mathrm{GS}\nu \mathrm{F}$. Moreover, most of the $\mathrm{GS}\nu \mathrm{F}$ originates from stars distant from Earth about 5–10 kpc, implying that a large fraction of stellar neutrinos can reach us from the Galactic Center. Solar neutrinos and the diffuse supernova neutrino background have energies comparable to those of the $\mathrm{GS}\nu \mathrm{F}$, challenging the detection of the latter. However, directional information of solar neutrino and $\mathrm{GS}\nu \mathrm{F}$ events, together with the annual modulation of the solar neutrino flux, could facilitate the $\mathrm{GS}\nu \mathrm{F}$ detection; this will kick off a new era for low-energy neutrino astronomy, also providing a novel probe to discover new physics.

The LHAASO observatory has recently measured details of the cosmic-ray (CR) spectrum in the knee region (1–10 PeV) with unprecedented precision, including its average CR mass composition and the spectrum of the proton component. We use these precision measurements, combined with direct measurements of CRs by space-based detectors, to derive predictions for the spectrum of diffuse $\gamma$-ray and neutrino emission from the interstellar medium under the assumption that the CR spectrum is universal throughout the Milky Way. We compare these predictions with the Fermi-LAT and LHAASO measurements of the diffuse $\gamma$-ray flux from inner and outer Galactic plane regions and with estimates of the neutrino flux based on the IceCube data for the same Galactic plane regions. We notice that the model predictions exceed LHAASO $\gamma$-ray measurements at energies above 100 TeV. This excess can be interpreted within a CR knee model assuming a “local PeV CR bubble.” Within this model, we infer the extension of the local PeV CR bubble of $1.1\pm 0.2\mathrm{kpc}$ in the direction of the inner Galaxy and of $0.5\pm 0.3\mathrm{kpc}$ toward the outer Galaxy.

X-ray reflection spectroscopy has evolved as one of the leading methods to measure black hole spins. However, the question is whether its measurements are subjected to systematic biases, especially considering the possible discrepancy between the spin measurements inferred with this technique and those from gravitational wave observations. In this work, we use general relativistic magnetohydrodynamic (GRMHD) simulations of thin accretion disks around spinning black holes for modeling the accretion process, and then we simulate NuSTAR observations to test the capability of modern reflection models in recovering the input spins. For the first time, we model the electron density and ionization profiles from GRMHD-simulated disks. Our study reveals that current reflection models work well only for fast-rotating black holes. We model the corona as the base of the jet and we find that reflection models with lamppost emissivity profiles fail to recover the correct black hole spins. Reflection models with broken power-law emissivity profiles perform better. As we increase the complexity of the simulated models, it is more difficult to recover the correct input spins, pointing toward the need to update our current reflection models with more advanced accretion disks and coronal geometries.

We introduce a novel method to bootstrap crossing equations in conformal field theory (CFT) and apply it to finite temperature theories on $S^1\times {\mathbb{R}}^{d-1}$. The proposed approach does not rely on positivity constraints and does not employ uncontrolled truncation schemes. Instead, we capture the contribution of an infinite number of operators in conformal block expansions using suitable functions, which are bootstrapped (numerically) together with a finite number of exposed CFT data. Our approach at finite temperature employs three key ingredients: (1) the Kubo-Martin-Schwinger (KMS) condition, (2) thermal dispersion relations, and (3) neural networks that model spin-dependent tail functions within the conformal block expansions. We test the efficiency of the new method in the case of generalized free fields and use it to perform a preliminary bootstrap analysis of double-twist thermal data in holographic CFTs.

We investigate the asymmetric propagation of 100 TeV electrons (whose radiation mainly concentrates on 20–30 TeV) in turbulent magnetic fields around pulsars, using graphics processing unit-accelerated simulations to explore their trajectories and interactions within pulsar wind nebulae and the interstellar medium. Key results include the identification of “mirage” sources indicating significant offsets in high-energy emissions from their originating pulsars, challenging the results of traditional symmetric diffusion models. By varying parameters like source distance, magnetic field strength, and electron injection spectral index, the study delineates their effects on observable phenomena such as the identified number of sources, as well as the source separation. Our results offer insights into some puzzling sources observed recently by the Large High Altitude Air Shower Observatory and shed light on the cosmic-ray transport mechanism in the interstellar medium.

We present a cosmological analysis of the third-order aperture mass statistic using Dark Energy Survey Year 3 (DES Y3) data. We perform a complete tomographic measurement of the three-point correlation function of the Y3 weak lensing shape catalog with the four fiducial source redshift bins. Building upon our companion methodology paper, we apply a pipeline that combines the two-point function ${\xi }_{\pm }$ with the mass aperture skewness statistic $⟨{\mathcal{M}}_{\mathrm{ap}}^3⟩$, which is an efficient compression of the full shear three-point function. We use a suite of simulated shear maps to obtain a joint covariance matrix. By jointly analyzing ${\xi }_{\pm }$ and $⟨{\mathcal{M}}_{\mathrm{ap}}^3⟩$ measured from DES Y3 data with a $\mathrm{\Lambda }\mathrm{CDM}$ model, we find $S_8=0.780\pm 0.015$ and ${\mathrm{\Omega }}_{\mathrm{m}}=0.266_{-0.040}^{+0.039}$, yielding 111% of figure-of-merit improvement in the ${\mathrm{\Omega }}_m\text{−}{S}_8$ plane relative to ${\xi }_{\pm }$ alone, consistent with expectations from simulated likelihood analyses. With a $w\mathrm{CDM}$ model, we find $S_8=0.749_{-0.026}^{+0.027}$ and $w_0=-1.39\pm 0.31$, which gives an improvement of 22% on the joint $S_8\text{−}{w}_0$ constraint. Our results are consistent with $w_0=-1$. Our new constraints are compared to CMB data from the Planck satellite, and we find that with the inclusion of $⟨{\mathcal{M}}_{\mathrm{ap}}^3⟩$ the existing tension between the datasets is at the level of $2.3\sigma$. We show that the third-order statistic enables us to self-calibrate the mean photometric redshift uncertainty parameter of the highest redshift bin with little degradation in the figure of merit. Our results demonstrate the constraining power of higher-order lensing statistics and establish $⟨{\mathcal{M}}_{\mathrm{ap}}^3⟩$ as a practical observable for joint analyses in current and future surveys.

We present a “dictionary” to expedite the identification of potential deviations in gravitational waveforms from those predicted by general relativity (GR) during the inspiral phase of black hole binaries. Assuming deviations from GR can be described by a local effective field theory (EFT) formulated in terms of curvature operators (and possibly additional scalar fields), this dictionary characterizes how deviations scale with the masses of the binary components and identifies the leading order post-Newtonian corrections in generic theories constructed within the EFT framework. By establishing a direct connection between observations and candidate theories beyond GR, this dictionary also aids in distinguishing genuine physical effects from systematic errors. These results can be readily incorporated into essentially all existing tests for the inspiral regime and, in particular, facilitate a more efficient combination of data from multiple events.

We present a new set of numerical-relativity simulations of merging binary neutron stars, aiming to identify possible observable signatures of the slope of the symmetry energy $L_{\mathrm{sym}}$. To achieve this goal, we employ a set of equations of state based on a parametrization of the covariant density functional theory of nuclear matter that allows controlled variations of $L_{\mathrm{sym}}$ and the skewness $Q_{\mathrm{sat}}$, holding the latter fixed. For a set of our simulations, we identify a steep energy gradient in the equation of state at subsaturation densities, which acts as a source of heating with subsequent stiffening produced by thermal support. Accounting for related structural modifications in the tidal deformability reconciles our results with theoretical expectations. On the other hand, we show that gravitational waves are unlikely to distinguish the role of $L_{\mathrm{sym}}$. In contrast to this, we find that the ejecta composition is significantly altered in our simulations, which employ an M1 moment scheme, when $L_{\mathrm{sym}}$ is varied. Based on our extracted dynamical ejecta properties, we compute r-process yields and find that they are distinct for the different $L_{\mathrm{sym}}$, especially at lower mass numbers $A\lesssim 120$. This suggests that electromagnetic counterparts are more likely to exhibit signatures; however, a direct connection to $L_{\mathrm{sym}}$ remains a challenge, given the complex interplay between details of the ejecta properties and the kilonova signal.

Dynamical tides of neutron stars in the late stages of binary inspirals provide a viable probe into dense matter through gravitational waves and potentially trigger electromagnetic precursors. We model the tidal response as a set of driven harmonic oscillators, where the natural frequencies are given by the quasinormal modes of a nonrotating neutron star. These modes are calculated in general relativity by applying linear perturbation theory to stellar models that include a solid crust and compositional stratification. For the mode spectrum, we find that the canonical interface mode associated with crust-core boundary vanishes in stratified neutron stars and is replaced by compositional gravity modes with mixed gravity-interfacial character, driven primarily by strong buoyancy in the outer core. We also find that fluid modes such as the core gravity mode and the fundamental mode can penetrate the crust, and we establish a criterion for such penetration. Regarding the tidal interaction, we find that transfer of binding energy to oscillations is dominated by the fundamental mode despite its frequency being too high to resonate with the tidal forcing. In general, we find that lower-frequency modes induce gravitational-wave phase shifts smaller than $\sim {10}^{-3}\mathrm{rad}$ for the equation of state we consider. We discover that nonresonant fundamental and crustal shear modes can trigger crust breaking already near the first gravity-mode resonance, while gravity-mode resonance concentrates strain at the base of the crust and may marginally crack it. These results suggest that both resonant and nonresonant excitations can overstress the crust and may channel energy into the magnetosphere prior to merger, potentially powering electromagnetic precursors. Our work represents an important step toward realistic modeling of dynamical tides of neutron stars in multimessenger observations.

The study of a wide peaking structure in the $B_c^{+}\gamma$ mass spectrum is reported using a data sample of proton-proton collisions collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{-1}$. The observed structure is consistent with the lowest excited $P$-wave $B_c^{+}$ states and exhibits a statistical significance exceeding 7 standard deviations relative to the background-only hypothesis. A two-peak model serves as an effective description of the data, with various theory-constrained models further explored to provide physical interpretation. Based on the predictions for the $B_c(1P{)}^{+}$ spectrum, the relative production cross section of the overall $B_c(1P{)}^{+}$ states with respect to the $B_c^{+}$ ground state with the transverse momentum $p_{\mathrm{T}}$ and rapidity $y$ of $B_c^{+}$ mesons in the regions $p_{\mathrm{T}}<20\mathrm{GeV}/c$ and $2.0<y<4.5$ at $\sqrt{s}=13\mathrm{TeV}$ is measured to be $0.20\pm 0.03\pm 0.02\pm 0.03$, where the uncertainty terms represent statistical, systematic, and uncertainties related to the choice of theoretical models, respectively. The results provide a test of theoretical models and deepen our understanding of quantum chromodynamics.

In this work, we study the dynamics of an extreme mass-ratio inspiral (EMRI) embedded within a scalar cloud populated around the massive black hole. This cloud may be generated through the black hole superradiant process if the wavelength of the scalar particle is comparable to the size of the massive black hole. The EMRI motion perturbs the cloud, producing scalar radiation toward infinity and into the black hole horizon. In addition, the backreaction of the scalar radiation onto the orbit modifies the motion of the EMRI and induces an observable gravitational-wave phase shift for a range of system parameters. We quantify the scalar flux and the induced phase shift, as one of the examples of exactly solvable, environmental effects of EMRIs.

In this article, we generalize the recursion methods based on cut equations [N. Arkani-Hamed, H. Frost, and G. Salvatori, arXiv:2412.21027.], originally developed for scalar theories, to gluons in pure Yang-Mills theory. In gauge theories, planar loop integrands are subtle to defined and obtained due to the existence of scaleless integrals. A critical challenge arises when constructing higher-loop integrands via recursion methods: integrands with or without all scaleless terms both are incompatible with the reconstruction formalism in Arkani-Hamed et al. To address this, we introduce a refined integrand by systematically removing specific scaleless contributions, and develop an algorithmic implementation of the recursion to all-loop level. We explicitly demonstrate the framework by three steps and obtain the recursion formula in pure Yang-Mills theory. In the Supplemental Material, we provide the results up to the two-loop five-point integrand and the simplified result in the large-$D$ limit for the three-loop four-point case.

We propose new bounds on black hole entropy in terms of the specific heat at fixed charges. For special spherically symmetric and static black holes ($g_{tt}{g}_{rr}=-1$), we prove the bounds with suitable sufficient energy conditions. For more general static and rotating black holes, we test the bounds with a variety of examples. This work extends the previously known algebraic inequalities of the black hole thermodynamic variables such as the Penrose inequality, to include their derivatives.

If primordial black holes (PBHs) are present in the early Universe, their contribution to the energy budget grows relative to that of radiation and generically becomes dominant unless the initial abundance is exponentially small. This black hole domination scenario is largely unconstrained for PBHs with masses $\lesssim {10}^9\mathrm{g}$, which evaporate prior to big bang nucleosynthesis. However, if the era of PBH domination is sufficiently long, the PBHs form clusters and can merge appreciably within these objects. We calculate the population statistics of these clusters within the Press-Schechter formalism and find that, for a wide range of PBH masses and Hubble rates at the onset of PBH domination, the mergers within PBH clusters can exhibit runaway behavior, where the majority of the cluster will eventually form a single black hole with a mass much greater than the original PBH mass. These mergers can dramatically alter the PBH mass distribution and leave behind merged relic black holes that evaporate after big bang nucleosynthesis and yield various observational signatures, excluding parameter choices previously thought to be viable.

Discrepancies between distance measurements and $\mathrm{\Lambda }\mathrm{CDM}$ predictions reveal notable features in the distance-redshift relation, possibly suggesting the presence of an evolving dark energy component. Given the central role of the Friedmann-Lemaître-Robertson-Walker (FLRW) metric in modeling cosmological distances, we investigate here whether these features instead point to a possible departure from the fundamental FLRW symmetries. Exploiting the transverse and line-of-sight distances provided by baryonic acoustic oscillations (BAO) observations, we demonstrate that observed distances hint at a slight but systematic preference for an anisotropic expansion rate emerging regardless of the dark energy model considered. Leveraging this non-FLRW feature, we investigate an inhomogeneous extension of the $\mathrm{\Lambda }\mathrm{CDM}$ model that naturally provides an anisotropic expansion rate. Our analysis demonstrates that models featuring spherical overdensities can explain BAO, supernova, and cosmic microwave background data, providing fits statistically indistinguishable from those obtained with a phantom dark energy scenario. When $\mathrm{Pantheon}+\mathrm{data}$ is considered, our analysis challenges the FLRW framework at $2.8\sigma$ and yields scenarios that can be interpreted as subtle but non-negligible deviations from the FLRW metric. When DESY5 supernovae are considered instead, deviations are notably more significant, yielding scenarios that mildly violate the Copernican principle and exclude the FLRW assumption at $5.2\sigma$. Overall, our results motivate a more in-depth investigation of whether the perfectly homogeneous and isotropic FLRW paradigm can still be assumed to accurately predict cosmological distances in the era of precision cosmology.

We discuss a new source of gravitational waves (GWs) from first-order phase transitions. The collisions of bubbles of the new phase can efficiently produce particles that couple to the background field undergoing the transition, thereby transferring a significant fraction of the released vacuum energy into a distribution of inhomogeneous and dynamic particle populations that persist long after the bubbles have disappeared. We study the GWs produced by such particle distributions, showing that GWs arise from the quadrupolar anisotropy in the radiation emitted from the bubble collisions, and present a semianalytical calculation of the two-point correlation function for the associated energy distributions. We find that this new contribution can qualitatively modify the overall GW signal from such phase transitions, creating a distinct shift in the spectral slope at low frequencies that could be observed by future GW experiments. It is therefore important to take this new contribution into account for any transition where the background field has significant self-coupling or couplings to other fields that could lead to efficient particle production at bubble collision.