The OGLE view of microlensing towards the Magellanic Clouds – I. A trickle of events in the OGLE‐II LMC data★
The OGLE view of microlensing towards the Magellanic Clouds – I. A trickle of events in the OGLE‐II LMC data★
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DOI：
10.1111/j.1365-2966.2009.15029.x
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发表时间：
2009-05
影响因子：
4.8
通讯作者：
Ł. Wyrzykowski;Ł. Wyrzykowski;S. Kozłowski;J. Skowron;V. Belokurov;M. Smith;A. Udalski;M. Szymański;M. Kubiak;G. Pietrzyński;G. Pietrzyński;I. Soszyński;O. Szewczyk;O. Szewczyk;K. Żebruń
中科院分区：
文献类型：
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作者：
Ł. Wyrzykowski;Ł. Wyrzykowski;S. Kozłowski;J. Skowron;V. Belokurov;M. Smith;A. Udalski;M. Szymański;M. Kubiak;G. Pietrzyński;G. Pietrzyński;I. Soszyński;O. Szewczyk;O. Szewczyk;K. Żebruń
我们提出的结果从光学引力透镜实验II（OGLE-II）调查（1996-2000年）对大麦哲伦云（LMC），其目的是检测银河系晕中的暗物质致密物体（MACHO）造成的微透镜现象。我们使用高分辨率的哈勃太空望远镜的OGLE领域的图像，并推导出在每个领域的监测恒星的数量的校正。这也产生了混合分布，我们使用的“目录级”蒙特卡洛模拟的微透镜事件，以计算检测效率的事件。我们在全明星样本中检测到两个微透镜事件的候选者，这意味着光学深度为0.43 ± 0.33 × 10−7。如果这两个事件都是由于星系核O引起的，那么致密暗物质天体在银河系晕中的质量分数将为8 ± 6%。然而，这个光学深度与事件的特征沿着似乎与自透镜假设一致，即自透镜本身就足以解释观测到的微透镜信号。我们的研究结果表明，没有检测到的MACHO透镜对LMC的上限，其丰富的银河系晕的19%的M= 0.4 M <$和10%的质量之间的0.01和0.2 M <$。
We present the results from the Optical Gravitational Lensing Experiment II (OGLE-II) survey (1996–2000) towards the Large Magellanic Cloud (LMC), which has the aim of detecting the microlensing phenomena caused by dark matter compact objects in the Galactic halo [massive compact halo objects (MACHOs)]. We use high-resolution Hubble Space Telescope images of the OGLE fields and derive the correction for the number of monitored stars in each field. This also yields blending distributions which we use in ‘catalogue-level’ Monte Carlo simulations of the microlensing events in order to calculate the detection efficiency of the events. We detect two candidates for microlensing events in the All Stars Sample, which translates into an optical depth of 0.43 ± 0.33 × 10−7. If both events were due to MACHO, the fraction of mass of compact dark matter objects in the Galactic halo would be 8 ± 6 per cent. This optical depth, however, along with the characteristics of the events seems to be consistent with the self-lensing scenario, i.e. self-lensing alone is sufficient to explain the observed microlensing signal. Our results indicate the non-detection of MACHOs lensing towards the LMC with an upper limit on their abundance in the Galactic halo of 19 per cent for M= 0.4 M⊙ and 10 per cent for masses between 0.01 and 0.2 M⊙.