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arXiv 2409.04818astro-ph.HE
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伽马射线双星 LS I+61° 303 超轨道调制的进动恒星盘模型

A precessing stellar disk model for superorbital modulations of the gamma-ray binary LS I+61$^{\circ}$ 303

A. M. Chen, J. Takata, Y. W. Yu

AI总结:

本文提出 LS I+61° 303 的超轨道调制源于 Be 星盘的进动,并通过解析模型重现了 X 射线轨道双峰和长时标调制,同时约束了中子星轨道偏心率和近星点相位,指出盘进动由中子星潮汐力矩驱动。

摘要:

伽马射线双星 LS I+61° 303 由一颗中子星和一颗 Be 星组成,轨道周期为 P_orb≈26.5 天。除了轨道调制之外,该双星在几乎所有波段都表现出长时标流量变化,其超轨道周期为 P_sup≈4.6 年。这种超轨道调制的起源目前仍不清楚。在脉冲星星风与恒星外流相互作用的图像下,我们提出 LS I+61° 303 的超轨道调制可能由 Be 盘的进动引起。假设 X 射线来自双星间激波的同步辐射,我们建立了一个解析模型来计算轨道相位和超轨道相位上的预期流量调制。在进动盘图像下,轨道光变曲线中的不对称双峰轮廓和类似正弦的长时标调制均得到了重现。观测到的 X 射线峰值轨道相位漂移以及我们对长时标 X 射线数据的拟合表明,中子星很可能以较小的偏心率绕 Be 星运动,且近星点相位约为 Φ_p∼0.6。我们将 LS I+61° 303 的 Corbet 图与其他 Be/X 射线双星进行比较,P_sup–P_orb 图中的线性相关性表明,LS I+61° 303 中 Be 盘的进动是由其中子星伴星的潮汐力矩引起的。

英文摘要:

Gamma-ray binary LS I+61$^{\circ}$ 303 consists of a neutron star orbiting around a Be star with a period of $P_{\rm orb}\simeq26.5\ {\rm d}$. Apart from orbital modulations, the binary shows long-term flux variations with a superorbital period of $P_{\rm sup}\simeq4.6\ {\rm yrs}$ as seen in nearly all wavelengths. The origin of this superorbital modulation is still not well understood. Under the pulsar wind-stellar outflow interaction scenario, we propose that the superorbital modulations of LS I+61$^{\circ}$ 303 could be caused by the precession of the Be disk. Assuming X-rays arise from synchrotron radiation of the intrabinary shock, we develop an analytical model to calculate expected flux modulations over the orbital and superorbital phases. The asymmetric two-peak profiles in orbital light curves and sinusoidal-like long-term modulations are reproduced under the precessing disk scenario. The observed orbital phase drifting of the X-ray peak and our fitting of long-term X-ray data indicate that the neutron star is likely orbiting around the star with a small eccentricity and periastron phase around $Φ_{\rm p}\sim0.6$. We compare the Corbet diagrams of LS I+61$^{\circ}$ 303 with other Be/X-ray binaries and the linear correlation in the $P_{\rm sup}-P_{\rm orb}$ diagram suggests that the precession of the Be disk in LS I+61$^{\circ}$ 303 is induced by the tidal torque of its neutron star companion.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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