Lifshitz black hole solutions pose particular challenges for reconciling the two main formulations of the classical double copy: the Kerr-Schild double copy and the Weyl double copy. Recent work has suggested that consistency between the two can be restored, in certain cases, only by adopting a regularization prescription in the Weyl double copy. In this paper, we test this prescription on three examples from the literature, each with a distinct novel feature, and show that the prescription remains valid in all cases.

Dark energy stars (DESs), described by the modified Chaplygin gas, can be dynamically stable and fall within different observational measurements. In this work, we employ diverse macroscopic properties, such as compactness $C$, moment of inertia $I$, tidal deformability $\mathrm{\Lambda }$, gravitational binding energy $E_g$, and $f$-mode nonradial pulsation frequency, to explore whether they are correlated by universal relations (URs). Remarkably, our stellar configurations always obey the causality condition and are compatible with several observational mass-radius constraints. Via the $C-I-\text{Love}-f$ URs, our results reveal that we cannot distinguish quark stars (QSs) from DESs in the sense that DESs satisfy several URs very similar to those of QSs. However, when we involve $E_g$, DESs and QSs can be strongly distinguished through the $I-E_g^{-2}$, $\mathrm{\Lambda }-E_g^{-5}$ and $f-E_g^{-2}$ URs. We also make use of these findings and the tidal deformability constraint from the GW170817 event to forecast the canonical properties of a $1.4M_{\odot }$ compact star. Furthermore, we present a set of fine empirical correlations involving the tidal deformability, obtained from an extensive scan of the parameter space of our DE stellar models.

Light dark matter candidates such as axions and dark photons generically couple to electromagnetism, yielding dark-matter-to-photon conversion as a key search strategy. In addition to resonant conversion in cavities and circuits, light dark matter bosons efficiently convert to photons on material interfaces, with a broadband power proportional to the total area of these interfaces. In this work, we make use of interface conversion to develop a new experimental dark matter detector design: the disordered dielectric detector. We show that a volume filled with dielectric powder is an efficient, robust, and broadband target for axion-to-photon or dark-photon-to-photon conversion. We perform semianalytical and numerical studies in small-volume 2D and 3D disordered systems to compute the conversion power as a function of the dark matter mass. We also discuss the power gathered onto a sensitive photodetector in terms of the bulk properties of the disordered material, making it possible to characterize the predicted dark-matter-to-photon conversion rate across a wide range of wavelengths. Finally, we propose DPHaSE: the Dielectric Powder Haloscope SNSPD Experiment, which is composed of a disordered dielectric target, a veto system, and a photon collection chamber to maximize the coupling between the powder target and a low-noise superconducting nanowire single-photon detector (SNSPD). With ambitious but realistic improvements to the sensor area and detection efficiency at low energy, the projected reach in the 10 meV–eV mass range is sensitive to QCD axion-photon couplings and exceeds current constraints on dark photon dark matter by up to 5 orders of magnitude.

We present the IMRPhenomXE frequency-domain phenomenological waveform model for the dominant mode of inspiral-merger-ringdown nonprecessing binary black holes in elliptical orbits. IMRPhenomXE extends the quasicircular IMRPhenomXAS waveform model for the dominant $(\ell ,|m|)=(2,2)$ modes to eccentric binaries. For the inspiral part, orbit-averaged equations of motion within the quasi-Keplerian parametrization up to third post-Newtonian order, including spin effects, are evolved, and the waveform modes are computed using the stationary phase approximation on eccentricity-expanded expressions up to $\mathcal{O}(e^{12})$. The model assumes circularization at merger ringdown, where it adopts the underlying quasicircular IMRPhenomXAS baseline. We show that IMRPhenomXE reduces to the accurate IMRPhenomXAS model in the quasicircular limit. Compared against 186 public numerical relativity waveforms from the Simulating eXtreme Spacetimes catalog with initial eccentricities up to 0.8, IMRPhenomXE provides values of unfaithfulness below 3% for 72% of simulations with initial eccentricities below 0.4. For larger eccentricities, the unfaithfulness degrades up to $\gtrsim 10\%$ due to the underlying small eccentricity expansions and additional modeling approximations. In terms of speed, IMRPhenomXE outperforms any of the existing inspiral-merger-ringdown eccentric waveform models. We demonstrate the efficiency, robustness, and modularity of IMRPhenomXE through injections into zero-noise and parameter-estimation analyses of gravitational-wave events, showing that IMRPhenomXE is a ready-to-use waveform model for gravitational-wave astronomy in the era of rapidly growing event catalogs.

The detection of ultrahigh-energy neutrinos (UHE-$\nu$), with energies above 10 PeV, has been a long-time goal in astroparticle physics. Autonomous, radio-frequency (RF) UHE-$\nu$ detectors have been deployed in polar regions that rely on the Askaryan effect in ice for the neutrino signal. The Askaryan effect occurs when the excess negative charge within a UHE-$\nu$ cascade radiates in a dense medium. UHE-$\nu$ can induce cascades that radiate in the RF bandwidth above thermal backgrounds. To identify UHE-$\nu$ signals in data from Askaryan-class detectors, analytic models of the Askaryan electromagnetic field have been created and matched to simulations and laboratory measurements. These models describe the Askaryan electromagnetic field but leave the effects of signal propagation through polar ice and RF channel response to simulations. In this work, a fully analytic Askaryan model that accounts for these effects is presented. First, formulas for the observed voltage trace and its Hilbert envelope are calculated. Second, the analytic model is compared to UHE-$\nu$ signals at 100 PeV from NuRadioMC, a key Monte Carlo tool set in the field. Correlation coefficients between the analytic signal envelope and Monte Carlo data in excess of 0.94 are found, and 99.99% of UHE-$\nu$ signals pass a correlation threshold of $\rho \ge 0.4$. Analysis of RF thermal noise reveals that just 0.2 background events have $\rho \ge 0.4$ in 5 years at a 1 Hz thermal trigger rate. Finally, we describe future work related to the measurement of the logarithm of the UHE-$\nu$ cascade energy.

We present an all-sky search for long-duration gravitational waves (GWs) from the first part of the LIGO-Virgo-KAGRA fourth observing run (O4), called O4a and comprising data taken between May 24, 2023, and January 16, 2024. The GW signals targeted by this search are the so-called “long-duration” ($\gtrsim 1\mathrm{s}$) transients expected from a variety of astrophysical processes, including nonaxisymmetric deformations in magnetars or eccentric binary coalescences. We make minimal assumptions on the emitted GW waveforms in terms of morphologies and durations. Overall, our search targets signals with durations of $\sim 1–1000\mathrm{s}$ and frequency content in the range 16–2048 Hz. In the absence of significant detections, we report the sensitivity limits of our search in terms of root-sum-square signal amplitude ($h_{\mathrm{rss}}$) of reference waveforms. These limits improve upon the results from the third LIGO-Virgo-KAGRA observing run (O3) by about 30% on average. Moreover, this analysis demonstrates substantial progress in our ability to search for long-duration GW signals owing to enhancements in pipeline detection efficiencies. As detector sensitivities continue to advance and observational runs grow longer, unmodeled long-duration searches will increasingly be able to explore a range of compelling astrophysical scenarios involving neutron stars and black holes.

Red giants (RGs) provide a promising astrophysical environment for capturing dark matter (DM) via elastic scattering with stellar nuclei. Captured DM particles migrate toward the helium-rich core and accumulate into a compact configuration. As the DM population grows, it can become self-gravitating and undergo gravitational collapse, leading to adiabatic contraction through interactions with the ambient medium. The resulting energy release, through elastic scattering and, where relevant, DM annihilation during collapse, locally heats the stellar core and can trigger helium ignition earlier than that predicted by standard stellar evolution. We analyze the conditions under which DM-induced heating leads to runaway helium burning and identify the critical DM mass required for ignition. Imposing the observational constraint that helium ignition must not occur before the observed luminosity at the tip of the RG branch, we translate these conditions into bounds on DM properties. Remarkably, we find that RGs are sensitive to DM, particularly with masses around ${10}^{11}\mathrm{GeV}$ and spin-independent scattering cross sections near ${10}^{-37}{\mathrm{cm}}^2$, which is comparable to the reach of current terrestrial direct detection experiments. Noteworthy, observations of RG stars provide a unique probe for high-mass and large-cross-section DM, a regime that remains currently inaccessible to direct detection experiments.

Recently, a hitherto unknown class of renormalization group stable relations between parameters of bosonic field theories has been identified and dubbed as the $r_0$ or “GOOFy” symmetries. Here, one-loop properties of the $r_0$ invariant two-Higgs doublet model and a minimal symmetric model are discussed. It is concluded that the symmetry is present at the one-loop provided the UV cutoff squared transforms nontrivially under $r_0$. The minimal model requires the presence of two real fields.

Motivated by the discrepancies noted recently between the theoretical predictions of the electromagnetic $J/\psi \to {\pi }^0{\gamma }^{*}$ transition form factor and the BESIII data, we reanalyze this transition form factor using the dispersive Khuri-Treiman equations, with final-state interactions in both the direct channel and the crossed channels properly considered. This improved framework incorporates $\rho –\omega$ mixing effects. The effect of four-pion states is evaluated through a dispersively improved vector-meson-dominance model. From this information, we propose a two-parameter fit that provides an excellent description of the BESIII data over the broad energy range from 0 to 2.8 GeV. We demonstrate that the $\rho {\pi }^0$ decay mode of the $J/\psi$ is dominated by strong interaction, while the $\omega {\pi }^0$ mode is dominated by one-photon exchange. From this, we extract the relative phase between the strong and the one-virtual-photon (electromagnetic) modes in hadronic decays of $J/\psi$ as $(62\pm 21)°$. This could provide useful information in understanding the long-standing $\rho \pi$ puzzle in $J/\psi$ decays.

We develop a formalism for resumming threshold double logarithms that appear in fragmentation functions for production of heavy quarkonia. Threshold singularities appear in fixed-order calculations of quarkonium fragmentation functions in the nonrelativistic QCD factorization formalism due to radiation of soft gluons. Because of this, fixed-order quarkonium fragmentation functions are not positive definite, and can lead to unphysically negative cross sections. This problem can be resolved by resumming threshold logarithms to all orders in perturbation theory, which renders the fragmentation functions finite and ensures the positivity of cross sections. We present a detailed derivation of the resummation formalism and derive the formula for resummed quarkonium fragmentation functions, which can be computed entirely within perturbation theory without the need for nonperturbative model functions.

In the era of Planck cosmology, the inflationary paradigm is best fitted toward the cosmological attractor scenarios, including the induced inflation, universal attractors, conformal attractors, and special attractors that are cataloged as $\xi$ models and $\alpha$ models. The recent hint from the ACT results pushes the scalar spectral index closer to the scale-invariant Harrison-Zeldovich spectrum, calling for a theoretical paradigm shift toward a Harrison-Zeldovich attractor, which is difficult to realize in the standard single-field slow-roll inflationary scenario. In this work, we achieve the Harrison-Zeldovich attractor scenario via nonminimal derivative coupling, attracting the monomial inflation, hilltop inflation, and $\alpha$-attractor E model toward the Harrison-Zeldovich spectrum.

Using late-Universe observations, we demonstrate that freeing dark energy and dark matter equations of state (EoS) dramatically alters the inferred strength and direction of their interactions. When dark sector EoS are fixed to $w_{\mathrm{de}}=-1$ and $w_{\mathrm{dm}}=0$, the data consistently favor an energy transfer from dark energy to dark matter across various interaction forms. This apparent evidence, however, proves highly sensitive to the EoS assumptions: treating $w_{\mathrm{de}}$ as a free parameter substantially weakens the evidence for interaction, with its value converging to the quintessence regime ($w_{\mathrm{de}}>-1$). In contrast, freeing $w_{\mathrm{dm}}$ maintains a preference for interaction, revealing a correlation where positive $w_{\mathrm{dm}}$ is associated with energy transfer from dark energy to dark matter, and negative $w_{\mathrm{dm}}$ with energy transfer from dark matter to dark energy. These findings caution against the simplistic assumption of Lambda cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) EoS values when attempting to detect a possible interaction. Despite these fundamental degeneracies, the model comparison indicates that interacting dark energy scenarios are positively to strongly supported by Akaike information criterion and deviance information criterion, but only inconclusively to weakly supported by Bayesian evidence against the $\mathrm{\Lambda }\mathrm{CDM}$ model.

We study the energy-momentum tensor of the spherically symmetric nontopological solitons of the $O(3)$ nonlinear sigma model with a standard kinetic term and with a symmetry breaking potential in ($3+1$)-dimensional flat spacetime. We evaluate the distributions of the corresponding energy density, shear forces, and pressure and study the stability criteria for these solutions. We argue that the presence of domains with negative energy density and violation of the energy conditions most likely do not lead to destabilization of solitons.

We study the dynamics of multiparticle Carroll-Schrödinger (C-Sch) quantum systems in $1+1$ dimensions, where $x$ acts as the evolution variable and $t$ as the configuration coordinate. We derive the $N$-body theory on equal-$x$ slices as the post-Carrollian limit of a relativistic multitime Klein-Gordon model, introducing temporal interactions via minimal coupling to the temporal energy operators. An $x$-dependent gauge transformation maps this to an equivalent description with explicit many-body potentials, illustrated by a temporal coupled-oscillator model that exhibits synchronization. Adopting a complementary spatial viewpoint with a static potential $U_{\mathrm{tot}}(\mathbf{x})$, we show that the evolution is driven by the collective force ${\sum }_j{\partial }_{x_j}{U}_{\mathrm{tot}}$. For any translation-invariant interaction (such as a regularized Coulomb potential), these internal forces cancel, rendering the collective dynamics free and highlighting post-Carrollian ultralocality. We also construct coordinate duality mapping separable Schrödinger Hamiltonians to C-Sch generators via Schwarzian derivatives. Exchange symmetry is formulated in the time domain, yielding temporal bunching for bosons and antibunching for fermions via the second-order coherence function $g^{(2)}(t,t^{\prime })$. In second quantization, the contact limit yields a temporal derivative cubic-quintic nonlinear Schrödinger equation with a theoretically fixed nonlinearity coefficient $\beta =-3/16$. Finally, by coupling canonical pairs to external scalar and gauge fields, we identify an isomorphism with one-dimensional current density functional theory, outlining a post-Carrollian Hohenberg-Kohn mapping and Kohn-Sham scheme.

Several statistics have been proposed for measuring the kinetic Sunyaev-Zeldovich (kSZ) effect by combining the small-scale CMB with galaxy surveys. We review five such statistics, and show that they are all mathematically equivalent to the optimal bispectrum estimator of type $⟨ggT⟩$. Reinterpreting these kSZ statistics as special cases of bispectrum estimation makes many aspects transparent, for example optimally weighting the estimator or incorporating photometric redshift errors. We analyze the information content of the bispectrum and show that there are two observables: the small-scale galaxy-electron power spectrum $P_{ge}(k_S)$, and the large-scale galaxy-velocity power spectrum $P_{gv}(k)$. The cosmological constraining power of the kSZ effect arises from its sensitivity to fluctuations on large length scales, where its effective noise level can be much better than galaxy surveys.

The recent preference for a dynamical dark energy (DE) from the dark energy spectroscopic instrument seems to call for interactions between DE and dark matter (DM), either from direct DE-DM interaction or indirect interaction induced by modified gravity. Therefore, an independent probe for these kinds of DE-DM interactions would be appealing from observational aspects. In this paper, we propose the black hole superradiance as a novel astrophysical probe for field-theoretic interacting DE-DM models, providing complementary constraints independent of large-scale cosmological observations. The core principle is that the DE-DM interaction can alter the effective mass of the superradiant ultralight boson, thereby modifying its superradiant instability rate around spinning black holes. We explore this connection through two distinct scenarios: a model where the DE field mediates a dark fifth force within the DM sector, affecting the superradiance from DM particles and a novel mechanism where the DE field itself becomes superradiant due to the effective mass enhancement induced by dense DM spikes around supermassive black holes. By applying a statistical framework to black hole observations in both scenarios, we derive constraints on the fundamental DE-DM coupling strength. Although the current constraints are rather loose due to small samples and inaccurate measurements, our work provides new astrophysical constraints on these interacting DE-DM scenarios and establishes a new synergy between black hole physics and cosmology for probing the fundamental nature of the dark sector.

We investigate the formation and relaxation of dark matter halos in the context of wave dark matter particles evolving on a background of a neutrino condensate. To this aim, we solved numerically the Schrödinger-Poisson system to model the dynamical evolution of ultralight bosonic dark matter particles in the presence of neutrino condensate. The latter appears as an additional source of the gravitational field in the Poisson equation, while its dynamical evolution and interaction with the environment are neglected. We found that, depending on the value of the cutoff parameter, the presence of the background neutrino condensate can affect the formation and relaxation of wave dark matter halos. Nevertheless, for value of the cutoff of the order of a few eV, the two species can coexist showing only marginal differences with the only-wave dark matter case. These results open the possibility of investigating more complex cosmological scenarios involving the formation of dark matter halos.

Massive scalar fields on black hole backgrounds generally admit two families of modes: quasibound states (QBSs) and quasinormal modes (QNMs). We demonstrate the orthogonality between the two mode families with respect to a relativistic product. We also find that, although the two families appear on different Riemann sheets of the Green’s function of massive scalar perturbations, they can be brought to a single sheet with an appropriate redefinition of the frequency variable. In this variable, it is more natural to see how both mode families can be excited by initial data, and to approximate the Green’s function with saddle points. Finally, we investigate the QNM emission from boson clouds—the latter effectively consisting of a single QBS—driven by the tidal perturbation of a second compact object. We show that while the resonant emission of QNMs is generally suppressed, QNM transitions may be more prominent when the interaction with the perturber is nonresonant, such as in the dynamical capture of unbound objects, and when the perturber transits close to the light ring.

We study high-energy neutrino production from interactions between supernova (SN) ejecta and the surrounding circumstellar material (CSM), focusing on regular Type II and Type IIn SNe. Using observationally inferred CSM density distributions, we calculate the resulting neutrino fluxes and examine their dependence on key parameters, including the CSM density normalization $D_{*}$, outer radius $R_{\mathrm{csm}}$, proton acceleration efficiency ${\epsilon }_p$, and magnetic energy fraction ${\epsilon }_B$. Detection prospects are assessed with a binned likelihood analysis for IceCube, indicating that nearby SNe with moderately dense, confined CSM can produce detectable signals, with a typical detection horizon of $\sim 0.1–1\mathrm{Mpc}$. For a Galactic SN at $\sim 10\mathrm{kpc}$, high-statistics neutrino data with detailed temporal and spectral information can constrain $D_{*}$, $R_{\mathrm{csm}}$, and ${\epsilon }_p$ to within a factor of $\sim 10$ or to a precision of $\sim 20\%$, depending on the assumed values of $D_{*}$ and $R_{\mathrm{csm}}$. These neutrino signals thus provide a complementary probe of the CSM profile and shock acceleration, alongside traditional electromagnetic observations.