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arXiv 2301.08975astro-ph.GA
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利用Vera Rubin天文台测量活动星系核时延的预期研究

Expectations for time-delay measurements in active galactic nuclei with the Vera Rubin Observatory

Bozena Czerny, Swayamtrupta Panda, Raj Prince, Vikram Kumar Jaiswal, Michal Zajacek, Mary Loli Martinez Aldama, Szymon Kozlowski, Andjelka B. Kovacevic, Dragana… 展开作者

Bozena Czerny, Swayamtrupta Panda, Raj Prince, Vikram Kumar Jaiswal, Michal Zajacek, Mary Loli Martinez Aldama, Szymon Kozlowski, Andjelka B. Kovacevic, Dragana Ilic, Luka C. Popovic, Francisco Pozo Nunez, Sebastian F. Hoenig, William N. Brandt

AI总结:

本研究模拟Vera Rubin天文台LSST巡天数据测量AGN发射线时延的前景,发现亮端类星体可通过主巡天、暗弱类星体可通过DDF十年数据实现可靠测量,但存在红移与光度相关的系统偏差,需校正以保障类星体宇宙学应用的准确性。

摘要:

Vera Rubin天文台将提供前所未有的时域天空观测数据集。计划开展的为期10年的空间与时间遗产巡天(Legacy Survey of Space and Time, LSST)将为深场钻探区(Deep Drilling Fields, DDFs)内的数千个活动星系核(active galactic nuclei, AGN)提供密集光变曲线,同时为数百万个AGN提供采样密度较低的光变曲线。本研究针对利用这些数据测量发射线相对于连续谱的时延的前景开展了模拟分析。\n研究采用Timmer-Koenig算法生成人工光变曲线,使用代表性观测采样率对其进行采样,并在光变曲线中加入预期的强发射线(Hβ、Mg II、C IV)、Fe II伪连续谱以及星光的污染贡献。研究根据红移选择合适的测光波段,针对100组光变曲线的统计实现,对比了假设的发射线时延与反演得到的时延。\n结果显示,对于类星体分布的亮端样本(约占所有源的15%),主巡天数据可在1σ误差范围内较好地测量发射线时延;对于DDFs中的更暗类星体,使用全部10年数据时的测量结果同样可靠。此外,利用前两年数据、甚至首个观测季的数据,也有望测量红移最小的最暗类星体的时延。对整个类星体种群的测量看似能获得高精度结果,但模拟中发现假设时延与反演时延之间存在依赖于红移和源光度的系统偏差,即便统计样本量很大,该偏差也不会消失。若不开展针对这类效应的校正模拟,该问题可能会影响半径-光度关系的斜率测量以及类星体的宇宙学应用。

英文摘要:

The Vera Rubin Observatory will provide an unprecedented set of time-dependent observations of the sky. The planned Legacy Survey of Space and Time (LSST) operating for 10 years will provide dense lightcurves for thousands of active galactic nuclei (AGN) in Deep Drilling Fields (DDFs) and less dense lightcurves for millions of AGN. We model the prospects for measuring time delays for emission lines with respect to the continuum, using these data. We model the artificial lightcurves using Timmer-Koenig algorithm, we use the exemplary cadence to sample them, we supplement lightcurves with the expected contamination by the strong emission lines (Hbeta, Mg II and CIV as well as with Fe II pseudo-continuum and the starlight). We choose the suitable photometric bands appropriate for the redshift and compare the assumed line time delay with the recovered time delay for 100 statistical realizations of the light curves. We show that time delays for emission lines can be well measured from the Main Survey for the bright tail of the quasar distribution (about 15% of all sources) with the accuracy within 1 sigma error, for DDFs results for fainter quasars are also reliable when all 10 years of data are used. There are also some prospects to measure the time delays for the faintest quasars at the smallest redshifts from the first two years of data, and eventually even from the first season. The entire quasar population will allow obtaining results of apparently high accuracy but in our simulations, we see a systematic offset between the assumed and recovered time delay depending on the redshift and source luminosity which will not disappear even in the case of large statistics. Such a problem might affect the slope of the radius-luminosity relation and cosmological applications of quasars if simulations correcting for such effects are not performed.

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