arXiv subjects

Peng-Fei Yin

Publications and source records attributed to Peng-Fei Yin.

At least 37 records · Page 2Linked to original sources

arXiv2025

Prediction of lithium isotope fluxes using data-driven production cross sections

Galactic cosmic rays (CRs) generally share common propagation features, leading to consistent spectral observations of secondary nuclei such as Li, Be, and B. However, the Li spectrum predicted by the CR diffusion coefficient inferred from B/C is significantly lower than the latest measurement of AMS-02. This anomaly may be attributed to the missing contributions from the heavy nuclei components in cosmic rays. By including these missing contributions the excess of the Li spectrum disappears. However, another inconsistency still exists since the calculated Li spectrum is now overestimated compared to the data. In this work, we update the cross-section model used to calculate the Li production according to more cross-section measurements. We find that the cross sections of these added reactions are systematically overestimated, and should be renormalized to the interpolations of available data. As a result, our prediction of the total Li spectrum is consistent with the measurement without discrepancy, and our prediction of the $\rm^6Li$ and $\rm^7Li$ spectra are consistent with the preliminary measurements of AMS-02 within the cross-section uncertainties.

astro-ph.HE↗

arXiv2025

Deciphering the spectral bumps of Galactic cosmic rays through gamma-ray observations of nearby molecular clouds

The observed spectral bump in cosmic-ray (CR) proton and helium spectra, along with the phase and amplitude evolution of CR dipole anisotropy, provide plausible yet indirect evidence for the presence of a nearby CR source. This study investigates the potential of giant molecular clouds (GMCs) located near the solar system to act as natural probes of CRs from the nearby source, with their gamma-ray emissions serving as indicators of spatial variations in CR flux within the solar neighborhood resulting from this source. We show that a nearby source, accounting for the CR data, could imprint distinct features on the $γ$-ray spectra of different GMCs. We expect that these features are detectable by LHAASO and upcoming high-energy $γ$-ray observatories, providing a powerful test for the hypothesized nearby source. Notably, we find that determining the energy dependence of the $γ$-ray spectral index offers a promising approach to investigate the nearby source and constrain its distance. Conversely, if the spectral bump is a widespread Galactic phenomenon, the energy dependence would exhibit uniformity across all GMCs, distinguishing the underlying mechanism accounting for the spectral bump from the scenario involving a nearby source.

astro-ph.HE↗

arXiv2025

Constraints on Axion-like Particles from the gamma-ray observation of the Galactic Center

High energy photons originating from the Galactic Center (GC) region have the potential to undergo significant photon-axion-like particle (ALP) oscillation effects, primarily induced by the presence of intense magnetic fields in this region. Observations conducted by imaging atmospheric Cherenkov telescopes have detected very high energy gamma-rays originating from a point source known as HESS J1745-290, situated in close proximity to the GC. This source is conjectured to be associated with the supermassive black hole Sagittarius A$^*$. The GC region contains diverse structures, including molecular clouds and non-thermal filaments, which collectively contribute to the intricate magnetic field configurations in this region. By utilizing a magnetic field model specific in the GC region, we explore the phenomenon of photon-ALP oscillations in the gamma-ray spectrum of HESS J1745-290. Our analysis does not reveal any discernible signature of photon-ALP oscillations, yielding significant constraints that serve as a complement to gamma-ray observations of extragalactic sources across a broad parameter region. The uncertainties arising from the outer Galactic magnetic field models have minor impacts on our results, except for ALP masses around 10$^{-7}$ eV, as the dominant influence originates from the intense magnetic field strength in the inner GC region.

astro-ph.HE↗

arXiv2024

Cosmic-ray deuteron excess from a primary component

The recent AMS-02 measurements of cosmic-ray (CR) deuteron fluxes suggest the presence of primary deuterons in quantities far exceeding predictions from Big Bang nucleosynthesis. This poses a significant challenge to modern astrophysics, as no known processes can account for such large amounts of deuterons without violating existing constraints~\cite{Epstein:1976hq}. In contrast, it is recently proposed that the AMS-02 measurements can be explained by a purely secondary origin when contributions from heavier nuclei are considered. In this study, we recalculate the secondary deuteron flux using production cross sections updated with the latest collider data. We find that some of the deuteron production cross sections are overestimated in the widely-used calculation tools for CR propagation, and a primary deuteron component is still necessary. We then propose a novel process for generating primary deuterons at CR sources through a fusion mechanism, which is naturally unique to deuterons. This model could explain the observed deuteron excess while maintaining consistency with other CR measurements.

astro-ph.HE↗

arXiv2024

A rigorous solution to the superluminal issue in the diffusion equation

Superluminal propagation is an intrinsic problem in the diffusion equation and has not been effectively addressed for a long time. In this work, a rigorous solution to this issue is obtained under the assumption that particles undergo a random flight process, where they move isotropically at a constant speed while experiencing random scatterings. We validate this solution by comparing it with comprehensive simulations of the random flight process and find that it significantly deviates from the solution derived from the Jüttner propagator. This solution is broadly applicable to various diffusion phenomena, such as cosmic-ray propagation. We emphasize that our rigorous solution is particularly crucial in scenarios involving burst-like particle injection, where previous phenomenological approaches to the superluminal diffusion problem may not yield accurate results.

astro-ph.HE↗

arXiv2024

SKA Sensitivity to Potential Radio Emission from Dark Matter Annihilation in Ursa Major III

The recently discovered stellar system, Ursa Major III/UNIONS 1, may be the faintest and densest dwarf spheroidal satellite galaxy of the Milky Way. Owing to its close proximity and substantial dark matter (DM) component, Ursa Major III emerges as a highly promising target for DM indirect detection. It is known that electrons and positrons originating from DM annihilation can generate a broad radio spectrum through the processes of synchrotron radiation and inverse Compton scattering within galaxies. In this study, we investigate the potential of the Square Kilometre Array (SKA) in detecting radio signatures arising from DM annihilation in Ursa Major III over a 100 hour observation period. Our analysis indicates that the SKA has strong capabilities in detecting these signatures. For instance, the SKA sensitivity to the DM annihilation cross section is estimated to reach $\mathcal{O}(10^{-30})-\mathcal{O}(10^{-28})\; \rm cm^{3} s^{-1}$ in the DM mass range from several GeV to $\sim100$ GeV for the $e^+e^-$ and $μ^+μ^-$ annihilation channels. The precise results are significantly influenced by various astrophysical factors, such as the strength of magnetic field, the diffusion coefficient, and the DM density profile in the dwarf galaxy. We discuss the impact of the uncertainties associated with these factors, and find that the SKA sensitivities have the potential to surpass the current constraints, even when considering these uncertainties.

hep-ph↗

arXiv2024

Determination of dark matter distribution in Ursa Major III and constraints on dark matter annihilation

The recently discovered satellite dwarf galaxy Ursa Major III provides a promising opportunity to explore the signatures resulting from dark matter (DM) annihilation, due to its proximity and large J-factor. Owing to the absence of an excess of $γ$-ray signatures originating from Ursa Major III, observations of $γ$-rays, such as those from Fermi-LAT, can be utilized to set constraints on the DM annihilation cross section. In this study, we determine the DM density profile, and consider the relationship between DM density and velocity dispersion at different locations within Ursa Major III through Jeans analysis. We calculate the J-factor of Ursa Major III for s-wave annihilation, along with the effective J-factors for p-wave and Sommerfeld enhanced annihilation scenarios. Utilizing these derived J-factors, we set stringent constraints on DM annihilation cross sections in three scenarios. Given the substantial impact of member star identification on the J-factor of Ursa Major III, we further calculate J-factors with the condition of excluding the largest velocity outlier. Our analysis reveals a notable reduction in the median value and an increase in the deviation of J-factors, thereby leading to considerably weaker constraints.

astro-ph.HE↗

arXiv2024

A theoretical perspective on the almost dark galaxy Nube: exploring the fuzzy dark matter model

In recent astronomical observations, an almost dark galaxy, designated as Nube, has unveiled an intriguing anomaly in its stellar distribution. Specifically, Nube exhibits an exceptionally low central brightness, with the 2D half-light radius of its stars far exceeding the typical values found in dwarf galaxies, and even surpassing those observed in ultra-diffuse galaxies (UDGs). This phenomenon is difficult to explain within the framework of cold dark matter (CDM). Meanwhile, due to its ultralight particle mass, fuzzy dark matter (FDM) exhibits a de Broglie wavelength on the order of kiloparsecs under the typical velocities of galaxies. The interference between different modes of the FDM wave gives rise to fluctuations in the gravitational field, which can lead to the dynamical heating of stars within galaxies, resulting in an expansion of their spatial distribution. In this paper, we aim to interpret the anomalous stellar distribution observed in Nube as a consequence of the dynamical heating effect induced by FDM. Our findings suggest that a FDM particle mass around $1-2\times 10^{-23}$ eV can effectively account for this anomaly. And we propose that the FDM dynamical heating effect provides a new insight into understanding the formation of field UDGs.

astro-ph.CO↗

arXiv2024

Tidal Formation of dark matter deficit diffuse galaxy NGC1052-DF2 by SIDM

Observations have revealed a significant dark matter deficit in the ultra-diffuse galaxy NGC1052-DF2 (DF2). It is widely accepted that the formation of this unique galaxy can be attributed to the tidal stripping of its host galaxy, NGC1052. In this study, we simulate the evolution of a satellite system containing globular clusters (GCs) within an accreting host halo in the framework of self-interacting dark matter (SIDM). Our simulation results suggest that the heightened tidal stripping resulting from DM self-interactions can give rise to the transformation of a conventional dwarf galaxy into a dark matter deficit galaxy resembling DF2. By comparing the simulation results with identical initial conditions in both the standard cold dark matter (CDM) and SIDM models, we find that the latter is more likely to replicate the properties of DF2. Furthermore, we demonstrate that a DF2 analog can also be produced on an orbit with a greater pericenter distance by increasing the strength of DM self-interactions. This suggests that the issue of extreme orbital parameters can be mitigated by implementing the SIDM model. The distributions of the GC population derived in our SIDM simulation are consistent with the observed characteristics of DF2. For comparison, we also explored the potential for achieving GC distributions in the context of CDM.

astro-ph.CO↗

arXiv2024

Reproduction of NGC1052-DF4 by self-interacting dark matter: dark matter deficiency and tidal features

Observations of the velocity dispersion indicate a severe dark matter (DM) deficit in the ultra-diffuse galaxy, NGC1052-DF4 (DF4). The ultra-deep images obtained with the Gemini telescope, which has the deepest imaging data till now, confirm the presence of tidal tails in DF4, suggesting its tidal formation. To enhance tidal effects, we consider the self-interaction among DM particles. Using an N-body simulation in the scenario of self-interacting dark matter (SIDM), we reproduce a DM-deficient galaxy that is consistent with all observational data of DF4. Specifically, our simulation result yields an extremely low DM-to-star mass ratio and a radial surface brightness profile very similar to that from deep images, showing accurate tidal features. By performing simulations with similar tidal effects and various cross-sections of SIDM, we show a significant impact of SIDM on the DM-to-star mass ratio in the central region of the galaxy. Our work confirms the tidal formation of DF4 in theory.

astro-ph.CO↗

arXiv2024

Impact of Parameters in the Blazar Jet Magnetic Field Model on Axion-Like Particle Constraints

The interaction between axion-like particles (ALPs) and photons induces ALP-photon oscillations in astrophysical magnetic fields, leading to spectral distortions in the $γ$-ray spectrum of blazars. The primary uncertainty of this phenomenon may originate from the magnetic field within the jet of the blazar. While many studies have explored the effects of ALP-photon oscillations using typical values for jet magnetic field parameters, it is important to recognize that these parameters can be constrained by multi-wavelength observations. In this study, we utilize the high energy $γ$-ray spectrum of Mrk 421 obtained from MAGIC and Fermi-LAT observations. By employing multi-wavelength fitting with a one-zone synchrotron self-Compton model, we derive the parameters characterizing the magnetic field model within the jet, and investigate their impacts on the ALP constraints.

astro-ph.HE↗

arXiv2024

Possible spectral irregularities in the AMS-02 positron spectrum

The excesses in the electron and positron spectra observed by many experiments, such as PAMELA and AMS-02, have sparked significant theoretical investigation. It is not easy to distinguish the two primary hypotheses dark matter annihilation/decay and pulsars from the spectral features. Should pulsars be the source of this excess, the expected variability in their distribution may introduce distinct irregularities in the positron energy spectrum. In this study, we use an irregularity estimator to detect these potential features in the positron energy spectrum of AMS-02. Our analysis of the current AMS-02 data reveals these spectral irregularities with a statistical significance of $1.75σ$. However, our projection indicates that, with AMS-02 data collected over a period of 20 years, such irregularities could be identified with a confidence level of $3σ$ level in 71\% of our simulations.

astro-ph.HE↗

arXiv2024

Constraints on Lorentz invariance violation from the LHAASO observation of GRB 221009A

In some quantum gravity (QG) theories, Lorentz symmetry may be broken above the Planck scale. The Lorentz invariance violation (LIV) may induce observable effects at low energies and be detected at high energy astrophysical measurements. The Large High Altitude Air Shower Observatory(LHAASO) has detected the onset, rise, and decay phases of the afterglow of GRB 221009A, covering a wide energy range of photons approximately from $0.2$ to $18$ TeV. This observation provides an excellent opportunity to study the Lorentz invariance violation effect. In this study, we simultaneously utilize the data from the KM2A and WCDA detectors of LHAASO, and apply two event by event methods, namely the pair view method and maximum likelihood method, to investigate LIV. We obtain stringent constraints on the QG energy scale. For instance, through the maximum likelihood method, we determine the 95$\%$ confidence level lower limits to be $E_{QG,1} > 14.7 (6.5)\times 10^{19}$GeV for the subluminal (superluminal) scenario of $n = 1$, and $E_{QG,2} > 12.0 (7.2)\times 10^{11}$GeV for the subluminal (superluminal) scenario of $n = 2$. We find that the rapid rise and slow decay behaviors of the afterglow can impose strong constraints on the subluminal scenario, while the constraints are weaker for the superluminal scenario.

astro-ph.HE↗

arXiv2024

Precise measurement of the cosmic-ray spectrum and $\left \langle \ln A \right \rangle$ by LHAASO -- connecting the Galactic to the extragalactic components

Recently LHAASO Collaboration gives precise measurements of cosmic rays (CR) all particle energy spectrum and mean logarithmic mass $\left \langle \ln A \right \rangle$ from 0.3 PeV to 30 PeV. Combining the CR measurements by AMS-02 and DAMPE in space and that by LHAASO and Auger on the ground we construct a model to recover all these measurements from tens of GeV to tens of EeV. We find the LHAASO measurement is crucial in the model construction by connecting the Galactic component to the extragalactic component. The precise measurements of CR spectra for individual species by AMS-02 and DAMPE together with the newest LHAASO results clearly indicates three Galactic CR components, that is, a soft low energy background, a hard high energy component, and a local source contribution. However, the LHAASO data show that above $\sim 10^{16}$ eV a nonnegligible extragalactic component must be included. Combining the Auger results and the LHAASO results we figure out the extragalactic CRs which need at least two components at lower and higher energies. Thanks to the precise measurements by LHAASO the constraints on the model parameters are quite stringent. The spectra features and mass measurements in all energy range are all well reproduced in the model.

astro-ph.HE↗

arXiv2024

Constraints on Axion-like Particles from Observations of Mrk 421 using the ${\rm CL_s}$ Method

Axion-like particles (ALPs) may undergo mixing with photons in the presence of astrophysical magnetic fields, leading to alterations in the observed high energy $γ$-ray spectra. In this study, we investigate the ALP-photon oscillation effect using the spectra of the blazar Mrk 421 over 15 observation periods measured by Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) and Fermi Large Area Telescope (Fermi-LAT). Compared with previous studies, we generate mock data under the ALP hypothesis and employ the ${\rm CL_s}$ method to set constraints on the ALP parameters. This method is widely utilized in high energy experiments and avoids the exclusion of specific parameter regions where distinguishing between the null and ALP hypotheses is challenging. We find that the ALP-photon coupling $g_{aγ}$ is constrained to be smaller than $\sim 2\times10^{-11}$ GeV$^{-1}$ for ALP masses ranging from $10^{-9}$ eV to $10^{-7}$ eV at the 95\% confidence level. We also present the constraints derived from the TS distribution under the null hypothesis, which is commonly utilized in previous astrophysical ALP studies. Our results reveal that the combined constraints of all the periods obtained from both methods are consistent. However, the ${\rm CL_s}$ method remains effective in cases where the latter method fails to provide constraints for specific observation periods.

astro-ph.HE↗

arXiv2024

Reexamine the dark matter scenario accounting for the positron excess in a new cosmic ray propagation model

The positron excess in cosmic rays has stimulated a lot of interests in the last decade. The dark matter origin of the extra positrons has attracted great attention. However, the $γ$-ray search set very stringent constraints on the dark matter annihilation/decay rate, which leads to great disfavor of the dark matter scenario. In the work, we incorporate the recent progress in cosmic rays propagation and reexamine the dark matter scenario accounting for the positron excess. Recent observations indicate that cosmic rays propagation in the Milky Way may be not uniform and diffusion in the Galactic disk should be slower than that in the halo. In the spatial-dependent propagation model, the positrons/electrons are more concentrated in the disk and lead to smaller dark matter annihilation/decay rate to account for the positron excess and also a smaller deficit in the background positron flux. Especially for the $μ^+μ^-$ channel the positron spectrum fit the AMS-02 latest data perfectly and the annihilation rate satisfies all the present constraints from $γ$-ray and CMB observations.

astro-ph.HE↗

arXiv2024

Reanalysis of the Systematic Uncertainties in Cosmic-Ray Antiproton Flux

Recent studies on cosmic rays (CRs) have reported the possibility of an excess in the antiproton flux around $10-20$ GeV. However, the associated systematic uncertainties have impeded the interpretation of these findings. In this study, we conduct a global Bayesian analysis to constrain the propagation parameters and evaluate the CR antiproton spectrum, while comprehensively accounting for uncertainties associated with interstellar CR propagation, production cross sections for antiprotons and other secondaries, and the charge and energy dependent effects of solar modulation. We establish that the most recent AMS-02 $\bar{p}$ spectrum is in agreement with a pure secondary origin. Based on this, we establish upper limits on dark matter (DM) annihilation. We also determine that the AMS-02 data favors the empirical hadronic interaction models over phenomenological ones. Finally, we find that the latest AMS-02 antiproton data from 2011 to 2018 disfavors the antiproton excess at $\mathcal{O}$(10) GeV and the corresponding DM interpretation that can simultaneously account for the Galactic Center excess in the gamma-ray observation.

astro-ph.HE↗

arXiv2024

Interpretation of AMS-02 beryllium isotope fluxes using data-driven production cross sections

The Be isotopic measurements preliminarily reported by the AMS-02 Collaboration have reached an unprecedented energy of 12 GeV/$n$. As secondary cosmic rays (CRs), the Be isotopes include both stable and unstable species, which are crucial for constraining the propagation parameters of Galactic CRs. However, uncertainties in their production cross sections can skew the interpretation of the CR data, especially when cross-section measurements are of significantly lower quality than CR measurements. In this work, we consider the uncertainties of the cross sections to interpret the Be isotopic data by adopting a cross-section parametrization that fully utilizes the available experimental data. Owing to the high-quality measurements of the $^7$Be production cross section, we innovatively employ $^7$Be instead of $^9$Be to constrain propagation parameters. Notably, the diffusion halo thickness is constrained to $5.67\pm0.76$~kpc, representing a moderate value compared to previous analogous works. Combining the well-constrained CR propagation model and the precise CR measurements of $^9$Be, we conversely constrain the major production cross section of $^9$Be and find that it ought to be remarkably lower than previously thought. Our analysis also questions the reliability of certain cross sections measured by some experiments, potentially marking the first time CR data has been used to identify dubious nucleon production cross sections. The method presented in this work holds promise for analyzing upcoming isotopic data from other nuclei.

astro-ph.HE↗