中子星磁层中类轴子粒子（ALP）-光子转换与逆康普顿再处理产生的伽马射线
Gamma Rays from ALP-Photon Conversion and Inverse Compton Reprocessing in Neutron Star Magnetospheres
浏览论文内容
中文总结 AI 辅助
本文研究中子星内部类轴子粒子产生及其在磁层中转换为光子的过程，结合银河磁场传播与逆康普顿再处理，评估其伽马射线信号的可探测性并推导观测约束与灵敏度。
中文摘要 AI 辅助
探索费米- LAT能量范围内中子星（NS）的类轴子粒子（ALP）信号，目前在很大程度上仍未被研究。具有极强磁场的中子星，如磁星和具有类磁星磁场的脉冲星，为ALP-光子转换提供了特别有前景的环境。磁星的特征是表面磁场高达$B_0\boldsymbol{\backsim}(10^{14}$--$10^{15})\boldsymbol{\rm G}$；然而，尽管磁场极强，在费米- LAT能量范围内尚未明确探测到稳定的磁星辐射，高能活动通常与罕见的爆发事件相关。本研究中，我们调查了不同类别中子星内部的ALP产生，以及这些ALP在其磁层中随后转换为光子的过程。ALP的发射率由恒星的密度和温度$T$决定，而转换概率因恒星周围的强磁场而增强。我们进一步考虑光子通过银河磁场的传播，这可为可观测光子通量提供额外贡献。我们研究了由此产生的伽马射线信号，并评估中子星磁层中ALP诱导的辐射是否能在费米- LAT波段的能量$E\boldsymbol{\backsim}100,\boldsymbol{\rm MeV}$以上被探测到。此外，我们还考虑磁层光子通过逆康普顿散射的再处理是否能将部分辐射转移到更高能量，并提供额外的观测信号。我们利用由此产生的通量，从现有伽马射线观测中推导约束条件，并估计未来MeV-GeV观测的灵敏度，以COSI作为代表性示例。
英文摘要
Exploring axion-like particle (ALP) signatures from neutron stars (NSs) in the \emph{Fermi}-LAT energy range remains largely unexplored. Neutron stars with exceptionally strong magnetic fields, such as magnetars and pulsars with magnetar-like magnetic fields, provide particularly promising environments for ALP--photon conversion. Magnetars are characterized by surface magnetic fields as large as $B_0\sim(10^{14}$--$10^{15})\,\mathrm{G}$; however, despite their extreme magnetic fields, no steady magnetar emission has been firmly detected in the \emph{Fermi}-LAT energy range, with high-energy activity generally associated with rare flaring episodes. In this work, we investigate ALP production in the interiors of different classes of NSs and the subsequent conversion of ALPs into photons in their magnetospheres. The ALP emissivity is determined by the stellar density and temperature $T$, while the conversion probability is enhanced by the strong magnetic fields surrounding the star. We further account for photon propagation through the Galactic magnetic field, which can provide an additional contribution to the observable photon flux. We investigate the resulting gamma-ray signatures and assess whether ALP-induced emission from NS magnetospheres could be detectable at energies $E\gtrsim100,\mathrm{MeV}$ in the \emph{Fermi}-LAT band. In addition, we consider if the reprocessing of the magnetospheric photons through inverse Compton scattering can shift part of the emission to higher energies and provide an additional observational signature. We use the resulting fluxes to derive constraints from existing gamma-ray observations and to estimate the sensitivity of future MeV--GeV observations, taking COSI as a representative example.
