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arXiv 1909.03092astro-ph.GA
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斯隆数字巡天混响测绘计划:滞后测量方法与模拟观测的比较

The Sloan Digital Sky Survey Reverberation Mapping Project: Comparison of Lag Measurement Methods with Simulated Observations

Jennifer I-Hsiu Li, Yue Shen, W. N. Brandt, C. J. Grier, P. B. Hall, L. C. Ho, Y. Homayouni, K. Horne, D. P. Schneider, J. R. Trump, D. A. Starkey

摘要:

我们研究了不同方法的性能,测量宽线和连续变化之间的时间滞后混响映射数据使用模拟光变曲线探测的节奏,时间基线,和信噪比的流量测量范围。我们比较了三种广泛采用的滞后测量方法:插值交叉关联函数(ICCF),z变换离散关联函数(ZDCF)和MCMC代码JAVELIN,模拟数据的质量典型的多目标光谱混响映射(MOS-RM)调查,同时监测数百个类星体。我们量化了这些方法中的每一种以及不同调查设计(例如,观察节奏和深度)。总体而言,JAVELIN和ICCF在基本所有测试中均优于ZDCF。与ICCF相比,JAVELIN产生更高质量的滞后测量,能够测量比观测节奏更短的时间尺度的更多滞后,不太容易受到季节性间隙和光变曲线中S/N退化的影响,并产生更准确的滞后不确定性。我们使用模拟光变曲线测量每种方法的Hbeta宽线区域大小-光度(R-L)关系,以评估MOS-RM调查设计的选择效应的影响。JAVELIN测量的R-L关系的斜率是三种方法中偏差最小的,并且在不同的调查设计中一致。这些结果表明,对于MOS-RM程序,JAVELIN明显优于其他两种非参数方法,特别是在大多数MOS-RM程序预期的有限光变曲线质量的情况下。

英文摘要:

We investigate the performance of different methodologies that measure the time lag between broad-line and continuum variations in reverberation mapping data using simulated light curves that probe a range of cadence, time baseline, and signal-to-noise ratio in the flux measurements. We compare three widely-adopted lag measuring methods: the Interpolated Cross-Correlation Function (ICCF), the z-transformed Discrete Correlation Function (ZDCF) and the MCMC code JAVELIN, for mock data with qualities typical of multi-object spectroscopic reverberation mapping (MOS-RM) surveys that simultaneously monitor hundreds of quasars. We quantify the overall lag detection efficiency, the rate of false detections, and the quality of lag measurements for each of these methods and under different survey designs (e.g., observing cadence and depth) using mock quasar light curves. Overall JAVELIN and ICCF outperform ZDCF in essentially all tests performed. Compared with ICCF, JAVELIN produces higher quality lag measurements, is capable of measuring more lags with timescales shorter than the observing cadence, is less susceptible to seasonal gaps and S/N degradation in the light curves, and produces more accurate lag uncertainties. We measure the Hbeta broad-line region size-luminosity (R-L) relation with each method using the simulated light curves to assess the impact of selection effects of the design of MOS-RM surveys. The slope of the R-L relation measured by JAVELIN is the least biased among the three methods, and is consistent across different survey designs. These results demonstrate a clear preference for JAVELIN over the other two non-parametric methods for MOS-RM programs, particularly in the regime of limited light curve quality as expected from most MOS-RM programs.

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