高能暂现源 · 每日文献综述

The Galactic diffuse gamma-ray emission is conventionally modeled as the product of cosmic-ray interactions with the interstellar medium. However, the cumulative contribution of stellar atmospheres acting as hadronic interaction targets remains an unexplored multimessenger background. In this work, we present the first systematic evaluation of this stellar diffuse emission by coupling MESA stellar evolution profiles and magnetic-field-modulated cosmic-ray transport with a 3D Galactic population synthesis framework. We find that the cumulative stellar contribution to the Galactic diffuse gamma-ray flux is negligible at 1 TeV, and the associated diffuse neutrino flux (<inline-formula><mml:math><mml:mrow><mml:mo>∼</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>17</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mrow><mml:mrow><mml:mi>TeV</mml:mi><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>cm</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext></mml:mrow><mml:msup><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>sr</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:mrow></mml:math></inline-formula>) remains orders of magnitude below current IceCube limits. Nevertheless, at ultrahigh energies (<inline-formula><mml:math><mml:mo>&gt;</mml:mo><mml:mn>10</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:math></inline-formula>), this emission establishes an irreducible local background that overtakes the strongly attenuated extragalactic isotropic gamma-ray background. Our results demonstrate that the Galactic stellar ensemble is a strictly subdominant background, indicating that stellar subtraction templates are not required for identifying Galactic PeVatrons or constraining dark matter annihilation.

We investigate equatorial periodic orbits and their gravitational wave radiation in the spacetime of an Euler-Heisenberg (EH) black hole surrounded by perfect fluid dark matter (PFDM). The combined effects of quantum electrodynamic corrections and dark matter are incorporated through an effective metric, and the dynamics of timelike geodesics are analyzed using the effective potential formalism. We derive the conditions for marginally bound and innermost stable circular orbits, classify periodic trajectories using the rational parameter and topological indices, and identify a rich hierarchy of zoom-whirl motions in the strong-field regime. Gravitational wave signals from periodic orbits are computed using the numerical kludge method, revealing characteristic burst-like features associated with whirl phases. For the parameter ranges considered here, the PFDM contribution modifies the location of the stability thresholds and can suppress the waveform amplitude by moving the relevant portions of the orbit away from the strongest-field region. The Euler-Heisenberg term, because of its r <SUP>-6</SUP> falloff, mainly affects the near-horizon part of the motion and can modify the high-frequency structure generated during whirl phases. These findings show that periodic timelike orbits provide a useful diagnostic of the interplay between nonlinear electromagnetic corrections and environmental matter in strong-field spacetimes.

We investigate a realistic nonsupersymmetric hybrid inflation model incorporating right-handed neutrinos and assess its viability in light of recent cosmological observations. At tree level, the inflaton potential yields a blue-tilted scalar spectrum, which is disfavored by current data from Planck and the Atacama Cosmology Telescope that instead support a red tilt. We show that including one-loop quantum corrections arising from generic couplings required for reheating significantly modifies the potential, flattening it at large field values. This leads to a red-tilted spectral index (<inline-formula><mml:math><mml:msub><mml:mi>n</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:mo>&lt;</mml:mo><mml:mn>1</mml:mn></mml:math></inline-formula>) and a suppressed tensor-to-scalar ratio <inline-formula><mml:math><mml:mi>r</mml:mi></mml:math></inline-formula>, both consistent with observational constraints. To ensure theoretical control, we focus on sub-Planckian field values, where the effective field theory description remains valid. The coupling of the inflaton to right-handed neutrinos naturally facilitates efficient reheating and enables the generation of the baryon asymmetry via nonthermal leptogenesis. We further explore the model's parameter space using a multioutput random forest classifier, achieving prediction accuracies in the range of 87.5% to 98.9%. Our analysis shows that approximately 15% of the parameter space satisfies at least one current experimental constraint, underscoring the essential role of quantum corrections in reconciling particle physics models with precision cosmology and highlighting the effectiveness of machine learning techniques in probing complex theoretical frameworks.

We study Bardeen-like regular black holes without Cauchy horizons via gravitational lensing. In the weak field, the deflection angle receives a positive ℓ-dependent correction, producing a slightly larger Einstein ring. For the galaxy ESO 325-G004, the predicted ring radius is consistent with current observations. In the strong field, for Sgr A* and M87*, the asymptotic position θ<SUB>∞</SUB> remains identical to the Schwarzschild value; however, SDL coefficients are ℓ-dependent, the angular separation s increases and the relative flux ratio r<SUB>mag</SUB> decreases as ℓ increases. Time delays between relativistic images for Sgr A* and M87* also increase mildly with ℓ. Our calculated values for these observables remain consistent with current observations. Future strong-field measurements of △T<SUB>2,1</SUB>, s, and r<SUB>mag</SUB> may offer a viable test for regular black holes free of Cauchy horizons and may distinguish Bardeen-like from Schwarzschild black holes.