标题： 用激光频率梳测量和表征HARPS的线轮廓 显示英文标题

标题： Measuring and characterizing the line profile of HARPS with a laser frequency comb

摘要： 目标。 我们研究了HARPS（高精度径向速度行星探测器）的二维光谱线轮廓，测量其在探测器上的位置变化以及线强度变化时的变化情况。 对线轮廓及其变化的表征对于实现10^{-10}或3.0 cm/s的波长尺度精度至关重要，以在类太阳恒星的适居区检测地球类行星。 方法。 我们使用了一种激光频率梳（LFC），其线条未分辨且未重叠，以探测仪器线轮廓。 我们将LFC光（通过各种中性密度滤光片衰减）注入HARPS的对象光纤和参考光纤，并研究了线轮廓随线强度的变化情况。 我们应用矩分析来测量线的位置、宽度和偏度，并表征由光谱仪和探测器引起的线轮廓失真。 基于此，我们建立了一个模型，通过跟踪两条光纤中的光束轮廓来校正点扩散函数失真。 结果。 我们证明线轮廓随着探测器上的位置和线强度的变化而变化。 这与HARPS探测器上的电荷转移不完整性（CTI）效应一致。 线位置的估计关键取决于线轮廓，因此线幅度的变化实际上会改变线的测量位置，影响仪器波长尺度的稳定性。 我们推导并应用了校正函数来重新校准并减轻这种影响，将其降低到与光子噪声一致的水平。 显示英文摘要

摘要： Aims. We study the 2D spectral line profile of HARPS (High Accuracy Radial Velocity Planet Searcher), measuring its variation with position across the detector and with changing line intensity. The characterization of the line profile and its variations are important for achieving the precision of the wavelength scales of 10^{-10} or 3.0 cm/s necessary to detect Earth-twins in the habitable zone around solar-like stars. Methods. We used a laser frequency comb (LFC) with unresolved and unblended lines to probe the instrument line profile. We injected the LFC light (attenuated by various neutral density filters) into both the object and the reference fibres of HARPS, and we studied the variations of the line profiles with the line intensities. We applied moment analysis to measure the line positions, widths, and skewness as well as to characterize the line profile distortions induced by the spectrograph and detectors. Based on this, we established a model to correct for point spread function distortions by tracking the beam profiles in both fibres. Results. We demonstrate that the line profile varies with the position on the detector and as a function of line intensities. This is consistent with a charge transfer inefficiency (CTI) effect on the HARPS detector. The estimate of the line position depends critically on the line profile, and therefore a change in the line amplitude effectively changes the measured position of the lines, affecting the stability of the wavelength scale of the instrument. We deduce and apply the correcting functions to re-calibrate and mitigate this effect, reducing it to a level consistent with photon noise.