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arXiv 2409.12441astro-ph.SRastro-ph.EPastro-ph.GAastro-ph.IM
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模拟TESS光变曲线中由分离致密天体引起的自透镜和掩食信号

Simulating Self-Lensing and Eclipsing Signals due to Detached Compact Objects in the TESS Light Curves

Sedighe Sajadian, Niayesh Afshordi

AI总结:

本研究模拟TESS观测中分离致密伴星(白矮星、中子星、黑洞)引起的自透镜和掩食信号,评估探测效率,并预测可发现的天体数量。

摘要:

银河系中有一部分恒星拥有致密伴星,这些伴星可能是白矮星(WD)、中子星(NS)或恒星质量黑洞(SBH)。在包含一颗主序星和一颗致密天体的分离且侧向(edge-on)双星系统中(分别记为WDMS、NSMS和BHMS系统),由于自透镜或掩食特征,恒星亮度会周期性变化。自透镜信号的形状是恒星半径和致密天体质量的简并函数,因为自透镜峰值强烈依赖于以爱因斯坦半径归一化的投影源半径。增大轨道倾角$i$会使自透镜形状从严格的矩形(top-hat)模型变为边缘缓慢上升的形状。我们模拟了这些双星系统被NASA的凌日系外行星巡天卫星(TESS)望远镜观测到的恒星光变曲线,并使用两组判据评估探测其周期信号的效率:(i)信噪比SNR$>3$且凌星次数$N_{\rm{tran}}>1$(低置信度,LC),以及(ii)SNR$>5$且$N_{\rm{tran}}>2$(高置信度,HC)。对于轨道倾角$i<20^{\circ}$的WDMS、NSMS和BHMS系统,在不同时间跨度内,HC探测效率分别为$5$-$7\\%$、$4.5$-$6\\%$和$4$-$5\\%$。仅在可探测的WDMS和NSMS事件中,分别有$\lesssim3\\%$和$\lesssim33\\%$可能探测到透镜引起的特征。对于距离更近、优先级更高的源恒星,探测效率更高,而当碰撞参数$b\gtrsim R_{\star}$时效率降为零,其中$b\simeq \tan(i) a$为碰撞参数($a$为半长轴)。我们预测从TESS候选目标列表恒星中发现的白矮星、中子星和恒星质量黑洞的数量分别为$15$-$18$、$6$-$7$和$<1$。

英文摘要:

A fraction of Galactic stars have compact companions which could be white dwarfs (WDs), neutron stars (NSs) or stellar-mass black holes (SBHs). In a detached and edge-on binary system including a main-sequence star and a compact object (denoted by WDMS, NSMS, and BHMS systems), the stellar brightness can change periodically due to self-lensing or eclipsing features. The shape of a self-lensing signals is a degenerate function of stellar radius and compact object's mass because the self-lensing peak strongly depends on the projected source radius normalized to Einstein radius. Increasing the inclination angle $i$ changes the self-lensing shape from a strict top-hat model to one with slow-increasing edges. We simulate stellar light curves due to these binary systems which are observed by NASA's Transiting Exoplanet Survey Satellite (TESS) telescope and evaluate the efficiencies to detect their periodic signatures using two sets of criteria (i)SNR$>3$ and $N_{\rm{tran}}>1$ (Low-Confidence, LC), and (ii) SNR$>5$ and $N_{\rm{tran}}>2$ (High-Confidence, HC). The HC efficiencies for detecting WDMS, NSMS, and BHMS systems with the inclination angle $i<20^{\circ}$ during different time spans are $5$-$7\%$, $4.5$-$6\%$, and $4$-$5\%$, respectively. Detecting lensing-induced features is possible in only $\lesssim3\%$ and $\lesssim33\%$ of detectable WDMS and NSMS events. The detection efficiencies for closer source stars with higher priorities are higher and drop to zero for $b\gtrsim R_{\star}$, where $b\simeq \tan(i) a$ is the impact parameter($a$ is the semi-major axis). We predict the numbers of WDs, NSs, and SBHs that are discovered from the TESS Candidate Target List stars are $15$-$18$, $6$-$7$, and $<1$.

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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