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Cosmic ray positrons from compact binary millisecond pulsars
Journal of Cosmology and Astroparticle Physics ( IF 6.4 ) Pub Date : 2021-02-15 , DOI: 10.1088/1475-7516/2021/02/030
M. Linares 1, 2, 3 , M. Kachelrieß 3
Affiliation  

A new population of neutron stars has emerged during the last decade: compact binary millisecond pulsars (CBMSPs). Because these pulsars and their companion stars are in tight orbits with typical separations of 1011 cm, their winds interact strongly forming an intrabinary shock. Electron-positron pairs reaccelerated at the shock can reach energies of about 10 TeV, which makes this new population a potential source of GeV-TeV cosmic ray positrons. We present an analytical model for the fluxes and spectra of positrons from intrabinary shocks of CBMSPs. We find that the minimum energy E&min; of the pairs that enter the shock is critical to quantify the energy spectrum with which positrons are injected into the interstellar medium. We measure for the first time the Galactic scale height of CBMSPs, ze = 0.4 ± 0.1 kpc, after correcting for an observational bias against finding them close to the Galactic plane. From this, we estimate a local density of 5–9 kpc−3 and an extrapolated total of 2–7 thousand CBMSPs in the Galaxy. We then propagate the pairs in the isotropic diffusion approximation and find that the positron flux from the total population is about two times higher than that from the 52 currently known systems. For E&min; between 1 and 50 GeV, our model predicts only a minor contribution from CBMSPs to the diffuse positron flux at 100 GeV observed at Earth. We also quantify the effects of anisotropic transport due to the ordered Galactic magnetic field, which can change the diffuse flux from nearby sources drastically. Finally, we find that a single “hidden” CBMSP close to the Galactic plane can yield a positron flux comparable to the AMS-02 measurements at 600 GeV if its line-of-sight to Earth is along the ordered Galactic field lines, while its combined electron and positron flux at higher energies would be close to the measurements of CALET, DAMPE and Fermi-LAT.



中文翻译:

紧凑型二进制毫秒脉冲星产生的宇宙射线正电子

在过去的十年中,出现了新的中子星群:紧凑的二毫秒毫秒脉冲星(CBMSP)。因为这些脉冲星和它们的伴星在紧密的轨道上,典型的间隔为10 11厘米,它们的风相互作用强烈,形成二元内冲击。激波中加速的电子-正电子对可以达到约10 TeV的能量,这使这一新种群成为GeV-TeV宇宙射线正电子的潜在来源。我们为CBMSPs的二元内激波提供了一个正电子通量和光谱的分析模型。我们发现最小的能量E &min;进入电击对的对中的一个对量化将正电子注入星际介质的能谱至关重要。我们第一次测量CBMSP的银河尺度高度,z e  = 0.4±0.1kpc,校正了观察偏差以防止发现它们接近银河系平面。据此,我们估计局部密度为5–9 kpc−3银河系中推断出的总数为2.7千个CBMSP。然后,我们以各向同性扩散近似法传播对,并发现来自总人口的正电子通量比来自52个当前已知系统的正电子通量高大约两倍。为了E &min;在1至50 GeV之间,我们的模型预测,在地球上观察到的100 GeV时,CBMSP对扩散正电子通量的贡献很小。我们还量化了有序银河磁场对各向异性输运的影响,该磁场可以极大地改变来自附近源的扩散通量。最后,我们发现,如果接近地球的视线是沿着有序的银河场线,那么接近银河平面的单个“隐藏” CBMSP可以产生与600 GeV的AMS-02测量结果相当的正电子通量。高能量下的电子和正电子的总通量将接近CALET,DAMPE和Fermi-LAT的测量值。

更新日期:2021-02-15
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