The origin of ear-like structures with two opposite lobes extending from the shell of supernova remnants (SNRs) remains a subject of active debate, with proposed mechanisms ranging from jet-driven explosions to interactions with bipolar circumstellar media. We present a novel investigation using Particle-in-Cell (PIC) simulations to examine the dynamics of a spherical ejecta in magnetized media, revealing a different formation mechanism for these structures. Our results demonstrate that particle acceleration is significantly enhanced along the magnetic-field direction, producing substantial modifications to shock morphology. These effects naturally generate elongated protrusions bearing a remarkable similarity to the observed SNR ear structures. This magnetic alignment scenario represents a distinct mechanism from the existing jet-based and circumstellar interaction models. Our findings suggest that magnetic field orientation may serve as a crucial diagnostic for distinguishing between different ear formation mechanisms in SNRs.

Particle acceleration in relativistic shocks of electron-positron plasmas with proton admixture is investigated through two-dimensional (2D) particle-in-cell (PIC) simulations. The upstream plasma, with a bulk Lorentz factor of $10$ and a magnetization parameter of 0.02, includes a small fraction of protons ($\sim 5\%$ by number). A relativistic perpendicular shock is formed by reflecting the flow off a conducting wall. The shock structure, electromagnetic fields, and particle energy spectra are analyzed. The particle density and the magnetic field have fluctuations. In the far-downstream region of the shock, positrons are accelerated to energies comparable to protons and develop a hard nonthermal component with a spectral index of $\sim 2$ in their energy spectrum, while electrons remain confined to lower energies. This asymmetry is attributed to the polarization properties of proton-driven electromagnetic waves, which favor positron acceleration. The results highlight the importance of plasma composition in shaping particle acceleration and nonthermal emission in relativistic shocks. These findings provide new insights into the microphysics of particle acceleration in astrophysical sources containing relativistic shocks.

The exploration of the surrounding world and the universe is an important theme in the legacy of humankind. The detection of gravitational waves is adding a new dimension to this grand effort. What are the fundamental physical laws governing the dynamics of the universe? What is the fundamental composition of the universe? How has the universe evolved in the past and how will it evolve in the future? These are the basic questions that press for answers. The space-based gravitational wave detector TianQin will tune in to gravitational waves in the millihertz frequency range ($10^{-4} \sim 1$ Hz, to be specific), opening a new gravitational wave spectrum window to explore many of the previously hidden sectors of the universe. TianQin will discover many astrophysical systems, populating the universe at different redshifts: some will be of new types that have never been detected before, some will have very high signal-to-noise ratios, and some will have very high parameter estimation precision. The plethora of information collected will bring us to new fronts on which to search for the breaking points of general relativity, the possible violation of established physical laws, the signature of possible new gravitational physics and new fundamental fields, and to improve our knowledge on the expansion history of the universe. In this white paper, we highlight the advances that TianQin can bring to fundamental physics and cosmology.

We derive the spin continuity equation by using the Noether's theorem. A new type of spin-tensor Hall current is found in the continuity equation. The spin-tensor Hall current is originating from the coupling of the spin-tensor and the momentum. The intrinsic spin Hall effect in the two-dimensional fermion model with the spin-orbit coupling and spin-tensor-momentum coupling is studied. The total spin Hall conductivity with the presence of the spin-tensor Hall current is calculated. The numerical results indicate that the total spin Hall conductivity is enhanced by the contribution of the spin-tensor-momentum coupling. The spin-tensor-momentum coupling may increase the spin transport in the intrinsic spin Hall effect.

By employing the Coulomb proximity potential model (CPPM) in conjunction with 22 distinct proximity potential models, we investigated the temperature dependence and the effects of proton number and neutron number on the diffusion parameters that determine the {\alpha}-decay half-lives of superheavy nuclei. The results indicate that the Prox.77-3 T-DEP proximity potential model yields the best performance, with the lowest root mean square deviation ({\sigma}=0.515), reflecting a high consistency with experimental data. In contrast, Bass77, AW95, Ngo80, and Guo2013 display larger deviations. The inclusion of temperature dependence significantly improves the accuracy of models such as Prox.77-3, Prox.77-6, and Prox.77-7. The -decay half-lives of 36 potential superheavy nuclei were further predicted using the five most accurate proximity potential models and Ni's empirical formula, with the results aligning well with experimental data. These predictions underscore the high reliability of the CPPM combined with proximity potential models in the theoretical calculation of {\alpha}-decay half-lives of superheavy nuclei, offering valuable theoretical insights for future experimental investigations of superheavy nuclei.

The correlation between the kinetic jet power $P_{\rm jet}$, intrinsic $\gamma$-ray luminosity ($L^{\rm int}$) and accretion ($L_{\rm disk}$) may reveal the underlying jet physics in various black hole systems. We study the relation between kinetic jet power, intrinsic $\gamma$-ray luminosity, and accretion by using a large sample of jetted AGN, including flat-spectrum radio quasars (FSRQs), BL Lacertae objects (BL Lacs), gamma-ray Narrow-line Seyfert 1 galaxies ($\gamma$NLS1s) and radio galaxies. Our main results are as follows: (1) The slope indices of the relation between $P_{\rm jet}$ and $L^{\rm int}$ are $0.85\pm0.01$ for the whole sample, $0.70\pm0.02$ for the FSRQs, $0.83\pm0.03$ for the BL Lacs, $0.68\pm0.11$ for the $\gamma$NLS1s, and $0.93\pm0.09$ for the radio galaxies, respectively. The jets in $\gamma$NLS1s and radio galaxies almost follow the same $P_{\rm jet}$-$L^{\rm int}$ correlation that was obtained for Fermi blazars. (2) The slope indices of the relation between $L^{\rm int}$ and $L_{\rm disk}$ are $1.05\pm0.02$ for the whole sample, $0.94\pm0.05$ for the FSRQs, $1.14\pm0.05$ for the BL Lacs, and $0.92\pm0.18$ for the $\gamma$NLS1s, respectively. The $\gamma$NLS1s and radio galaxies almost also follow the $L^{\rm int}$-$L_{\rm disk}$ correlation derived for Fermi blazars. (3) The jet power is larger than the luminosity of accretion disks for almost all jetted AGN. Jet power depends on both the Eddington ratio and black hole mass. We obtain $\log P_{\rm jet}\sim(1.00\pm0.02)\log L_{\rm disk}$ for the whole sample, which is consistent with the theoretically predicted coefficient. These results may imply that the jets of jetted AGN are powered by the Blandford-Znajek mechanism.

We present for the first time the timing and spectral analyses for a narrow-line Seyfert 1 galaxy, SBS 1353+564, using \it{XMM-Newton} and \it{Swift} multi-band observations from 2007 to 2019. Our main results are as follows: 1) The temporal variability of SBS 1353+564 is random, while the hardness ratio is relatively constant over a time span of 13 years; 2) We find a prominent soft X-ray excess feature below 2 keV, which cannot be well described by a simple blackbody component; 3) After comparing the two most prevailing models for interpreting the origin of the soft X-ray excess, we find that the relativistically smeared reflection model is unable to fit the data above 5 keV well and the X-ray spectra do not show any reflection features, such as the Fe K\alpha emission line. However, the warm corona model can obtain a good fitting result. For the warm corona model, we try to use three different sets of spin values to fit the data and derive different best-fitting parameter sets; 4) We compare the UV/optical spectral data with the extrapolated values of the warm corona model to determine which spin value is more appropriate for this source, and we find that the warm corona model with non-spin can sufficiently account for the soft X-ray excess in SBS 1353+564.

Quantum entanglement is essential for modern quantum information processing. Entanglement gates convert initially non-entangled states into entangled ones by applying time-dependent parametric pulses. While Bell state preparation has been experimentally validated in various platforms, its stability and fidelity are constrained by environmental decoherence and parametric this http URL, we propose a dynamical framework for preparing robust Bell states by leveraging time-boundary engineering and momentum-space projective measurements within Su-Schrieffer-Heeger (SSH) systems. Employing Lindblad master equation, we theoretically demonstrate that the prepared Bell states exhibit remarkable robustness against both environmental decoherence and parametric time fluctuations, achieving a nearly perfect quantum fidelity, with momentum conservation law governing this robust behavior. To enrich Bell states in momentum space, multi-band SSH models are designed to induce multifold time scattering processes. This time-boundary engineering framework is applicable to both fermionic and bosonic excitations, offering a robust paradigm for generating Bell states in quantum communication and quantum computation.

The theoretical model suggests that relativistic jets of AGN rely on the black hole spin and/or accretion. We study the relationship between jet, accretion, and spin using supermassive black hole samples with reliable spin of black holes. Our results are as follows: (1) There is a weak correlation between radio luminosity and the spin of black hole for our sample, which may imply that the jet of the supermassive black hole in our sample depends on the other physical parameters besides black hole spins, such as accretion disk luminosity. (2) The jet power of a supermassive black hole can be explained by the hybrid model with magnetic field of corona. (3) There is a significant correlation between radio-loudness and black hole spin for our sample. These sources with high radio-loudness tend to have high black hole spins. These results provide observational evidence that the black hole spin may explain the bimodal phenomena of radio-loud and radio-quiet AGN.

Both theoretical models and observational evidence indicate that jets and/or outflows driven by central active supermassive black holes exert a significant feedback effect on the overall properties of their host galaxies. Theoretical models suggest that the spin of supermassive black holes drives relativistic jets. Therefore, we investigate the relationship between black hole spin, star formation rate, and black hole mass using a sample of 48 low-redshift supermassive black holes. By performing multiband fitting of spectral energy distribution, we derive the star formation rates and stellar masses of the host galaxies harbouring these supermassive black holes. Our main results are as follows: (i) For black holes with masses \(M_{\rm BH} \lesssim 10^{6.5} M_{\odot}\), the spin increases with increasing black hole mass, suggesting that black hole growth is primarily driven by gas accretion, particularly in the coherent gas accretion regime. Conversely, for black holes with masses $M_{\rm BH} \gtrsim 10^{7.5} M_{\odot}$, the spin decreases with increasing black hole mass, indicating that growth occurs mainly through mergers, inducing chaotic accretion. (ii) At low star formation rates, black hole spin increases with increasing star formation rates, consistent with gas accretion. However, at high star formation rates, black hole spin decreases with increasing star formation rates, suggesting black hole mergers. The value of the black hole spin may be used to diagnose the star formation rate of the host galaxies through active galactic nuclei activities. (iii) Our data and analysis confirm the well-known relation between stellar mass and black hole mass, with the fitting function $\log M_{\rm BH}=0.57\log M_{*}+1.94$.

Here, we report a new intrinsic magnetic topological insulator FeBi$_2$Te$_4$ based on first-principles calculations and it can achieve a rich topological phase under pressure modulation. Without pressure, we predict that both FeBi$_2$Te$_4$ ferromagnetic and antiferromagnetic orders are non-trivial topological insulators. Furthermore, FeBi$_2$Te$_4$ of FM-z order will undergo a series of phase transitions from topological insulator to semimetals and then to trivial insulator under pressure. Finally, we further clarify and verify topological phase transitions with low-energy effective model calculations. This topological phase transition process is attributed to the synergy of the magnetic moment and the spin-orbit coupling. The unique topological properties of FeBi$_2$Te$_4$ will be of great interest in driving the development of quantum effects.

We have integrated nonlocal effects with the Bayesian neural network (BNN) approach to enhance the prediction accuracy of $\alpha$ decay half-lives. The results indicate that incorporating nonlocal effects significantly impacts half-life calculations, while the BNN method substantially improves prediction accuracy and demonstrates strong extrapolation capabilities. Using Shapley Additive Explanations (SHAP), we conducted a quantitative comparison among the four input feature parameters in the BNN, revealing that the $\alpha$ decay energy $Q_{\alpha}$ is the predominant contributor to $T_{1/2}$. Leveraging the BNN robust extrapolation capability, we predicted $\alpha$ decay half-lives for the isotopic chains (Z=118, 120), revealing a significant shell effect at N=184 of neutrons. Keywords: $\alpha$ decay, half-lives, nonlocal effects, Bayesian neural network, Coulomb and proximity potential model.

Based on Extreme Gradient Boosting (XGBoost) framework optimized via Bayesian hyperparameter tuning, we investigated the {\alpha}-decay energy and half-life of superheavy nuclei. By incorporating key nuclear structural features-including mass number, proton-to-neutron ratio, magic number proximity, and angular momentum transfer-the optimized model captures essential physical mechanisms governing $\alpha$-decay. On the test set, the model achieves significantly lower mean absolute error (MAE) and root mean square error (RMSE) compared to empirical models such as Royer and Budaca, particularly in the low-energy region. SHapley Additive exPlanations (SHAP) analysis confirms these mechanisms are dominated by decay energy, angular momentum barriers, and shell effects. This work establishes a physically consistent, data-driven tool for nuclear property prediction and offers valuable insights into $\alpha$-decay processes from a machine learning perspective.

In this work, we reanalyzed 11 years of spectral data from the \textit{Fermi} Large Area Telescope (\textit{Fermi}-LAT) of currently observed starburst galaxies (SBGs) and star-forming galaxies (SFGs). We used a one-zone model provided by \textbf{NAIMA} and the hadronic origin to explain the GeV observation data of the SBGs and SFGs. We found that a protonic distribution of a power-law form with an exponential cutoff can explain the spectra of most SBGs and SFGs. However, it cannot explain the spectral hardening components of NGC 1068 and NGC 4945 in the GeV energy band. Therefore, we considered the two-zone model to well explain these phenomena. We summarized the features of various model parameters, including the spectral index, cutoff energy, and protonic total energy. Similar to the evolution of supernova remnants (SNRs) in the Milky Way, we estimated the protonic acceleration limitation inside the SBGs to be likely in the order of 10$^{2}$ TeV using the one-zone model; this is close to those of SNRs in the Milky Way.

In this paper, we propose a novel minimal physical model to elucidate the long-term stochastic variability of blazars. The model is built on the realistic background of magnetized plasma jets dissipating energy through a turbulent cascade process that transfers energy to small-scale structures with highly anisotropic radiation. The model demonstrates the ability to spontaneously generate variability features consistent with observations of blazars under uniformly random fluctuations in the underlying physical parameters. This indicates that the model possesses self-similarity across multiple time scales, providing a natural explanation for the universal power spectral density (PSD) structure observed in different types of blazars. Moreover, the model exhibits that when the cascade process produces a relatively flat blob energy distribution, the spectral index of the model-simulated PSD in the high-frequency regime will be steeper than that predicted by the Damped Random Walk (DRW) model, which is in agreement with recent observations of active galactic nucleus (AGN) variability, providing a plausible theoretical explanation. The model is also able to reproduce the observed fractional variability amplitude (FVA) characteristics of blazars, and suggests that the specific particle acceleration and radiative cooling processes within the blob may not be the key factor shaping the long-term stochastic variability. This minimal model provides a new physical perspective for understanding the long-term stochastic variability of blazars.

Altermagnets, a newly discovered class of materials, exhibit zero net magnetization while hosting spin-split electronic bands. However, monolayer altermagnets maintain degenerate band gaps at the high-symmetry X and Y points in the Brillouin zone, manifesting a paravalley phase characterized by unpolarized valley states. In this work, we demonstrate that spontaneously broken valley degeneracy can be achieved through interlayer sliding in engineered M$_2$A$_2$B and M$_2$AA$'$B bilayer altermagnets by first-principles calculations and minimal microscopic model. We propose a promising route to achieve antiferromagnetic half-metal driven by sliding and emergent ferrovalley phase without applied electric field, which is realized in the V$_2$SSeO engineered bilayer. Our calculations also reveal that Mo$_2$O$_2$O exhibits the largest valley splitting gap of ~0.31 eV, making it a promising candidate for valley-spin valve devices. Furthermore, band structure calculations on Mo$_2$AA$'$O materials demonstrate that increasing the difference in atomic number ($\Delta$Z) between A and A$'$ site atoms effectively enhances valley polarization. This work establishes a novel platform for discovering and controlling ferrovalley states in altermagnetic systems.

In addition to electrons and protons, nonrelativistic quasiparallel shocks are expected to possess the ability to accelerate heavy ions. The shocks in supernova remnants are generally supposed to be accelerators of the Galactic cosmic rays, which consist of many species of particles. We investigate diffusive shock acceleration (DSA) of electrons, protons and helium ions in a nonrelativistic quasiparallel shock through 1D particle-in-cell (PIC) simulation with a helium-to-proton number density ratio of $0.1$, which is relevant for the Galactic cosmic rays. The simulation indicates that waves can be excited by the flow of the energetic protons and helium ions upstream of the nonrelativistic quasiparallel shock with a sonic Mach number of 14 and an alfvén Mach number of 19.5 in the shock rest frame, and the charged particles are scattered by the self-generated waves and accelerated gradually. Moreover, the spectra of the charged particles downstream of the shock are thermal plus a nonthermal tail, and the acceleration is efficient with about $7\%$ and $5.4\%$ of the bulk kinetic energy transferred into the nonthermal protons and helium ions in the near downstream region at the end of the simulation, respectively.

eHWC J2019+368 is one of the sources emitting $\gamma$-rays with energies higher than 100 TeV based on the recent measurement with the High Altitude Water Cherenkov Observatory (HAWC), and the origin is still in debate. The pulsar PSR J2021$+$3651 is spatially coincident with the TeV source. We investigate theoretically whether the multiband nonthermal emission of eHWC J2019+368 can originate from the pulsar wind nebula (PWN) G75.2$+$0.1 powered by PSR J2021$+$3651. In the model, the spin-down power of the pulsar is transferred to high-energy particles and magnetic field in the nebula. As the particles with an energy distribution of either a broken power-law or a power-law continually injected into the nebula, the multiband nonthermal emission is produced via synchrotron radiation and inverse Compton scattering. The spectral energy distribution of the nebula from the model with the reasonable parameters is generally consistent with the detected radio, X-ray and TeV $\gamma$-ray fluxes. Our study supports that the PWN has the ability to produce the TeV $\gamma$-rays of eHWC J2019+368, and the most energetic particles in the nebula have energies up to about $0.4$ PeV.

By employing the Coulomb proximity potential model (CPPM) in conjunction with 22 distinct proximity potential models, we investigated the temperature dependence and the effects of proton number and neutron number on the diffusion parameters that determine the {\alpha}-decay half-lives of superheavy nuclei. The results indicate that the Prox.77-3 T-DEP proximity potential model yields the best performance, with the lowest root mean square deviation ({\sigma}=0.515), reflecting a high consistency with experimental data. In contrast, Bass77, AW95, Ngo80, and Guo2013 display larger deviations. The inclusion of temperature dependence significantly improves the accuracy of models such as Prox.77-3, Prox.77-6, and Prox.77-7. The -decay half-lives of 36 potential superheavy nuclei were further predicted using the five most accurate proximity potential models and Ni's empirical formula, with the results aligning well with experimental data. These predictions underscore the high reliability of the CPPM combined with proximity potential models in the theoretical calculation of {\alpha}-decay half-lives of superheavy nuclei, offering valuable theoretical insights for future experimental investigations of superheavy nuclei.