SRGe J194401.8+284452——伽马射线源4FGL J1943.9+2841视场中的一颗X射线激变变星
SRGe J194401.8+284452 -- an X-ray Cataclysmic Variable in the Field of the Gamma-Ray Source 4FGL J1943.9+2841
AI总结：
本文通过多波段观测确定SRGe J194401.8+284452是一颗轨道周期约1.5小时、具有高低态跃迁和8分钟自转脉动的中等偏振星，并排除其与γ射线源4FGL J1943.9+2841的关联。
摘要：
SRGe J194401.8+284452是未证认γ射线源4FGL J1943.9+2841位置不确定椭圆内最亮的点状X射线天体。我们开展了多波段光谱和测光研究，以确定其性质及其与该γ射线源的可能关联。我们利用Gaia数据可靠地确定了它的光学对应体，距离约为415 pc。我们的数据表明，该天体是一颗激变变星，轨道周期约为1.5小时。SRGe J194401.8+284452在光学和X射线波段同时表现出高、低光度态之间的快速自发跃迁，在跃迁之间于数月/数年的时标上保持相对稳定。这可能是由吸积率发生一个量级的变化所致。在高态和低态下，该源在光学波段的亮度分别约为17等和20等，在0.3–10 keV能段的流量分别为5×10⁻¹²和5×10⁻¹³ erg/cm²/s。我们限制了白矮星的质量（0.3–0.9 M⊙）及其在低态下的温度（14750 ± 1250 K），以及供体星的质量（≤0.08 ± 0.01 M⊙）。在低态下，我们探测到规则的光学脉动，振幅为0.2等，周期为8分钟。它们很可能与白矮星的自转有关，而非其非径向脉动。在高态下，该天体仅在1–15分钟时标上表现出振幅为0.2–0.6等的随机光学亮度变化。我们得出结论，SRGe J194401.8+284452可被归类为中等偏振星（intermediate polar），其与该γ射线源的关联极不可能。
英文摘要：
SRGe J194401.8+284452 is the brightest point-like X-ray object within the position uncertainty ellipse of an unidentified $γ$-ray source 4FGL J1943.9+2841. We performed multi-wavelength spectral and photometric studies to determine its nature and possible association with the $γ$-ray source. We firmly established its optical counterpart with the Gaia based distance of about 415 pc. Our data show that the object is a cataclysmic variable with an orbital period of about 1.5 hours. SRGe J194401.8+284452 exhibits fast spontaneous transitions between the high and low luminosity states simultaneously in the optical and X-rays, remaining relatively stable between the transitions on scales of several months/years. This can be caused by an order of magnitude changes in the accretion rate. The brightness of the source is about 17 mag and 20 mag in the optical range and $5\times 10^{-12}$ and $5\times 10^{-13}$ erg/cm$^2$/s in the $0.3- 10$ keV range in the high and low states, respectively. We constrained the mass of the white dwarf ($0.3 - 0.9$ $M_\odot$) and its temperature in the low state (14750 $\pm$ 1250 K), the mass of the donor star ($\leq$ 0.08 $\pm$ 0.01 $M_ \odot$). In the low state, we detected regular optical pulsations with an amplitude of 0.2 mag and a period of 8 min. They are likely associated with the spin of the white dwarf, rather than with its non-radial pulsations. In the high state, the object demonstrates only stochastic optical brightness variations on time scales of $1 - 15$~minutes with amplitudes of $0.2 - 0.6$~mag. We conclude, that SRGe J194401.8+284452 can be classified as an intermediate polar, and its association with the $γ$-ray source is very unlikely.
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。
