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arXiv 2012.09175astro-ph.GA
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精密弱透镜中的形状噪声和色散

Shape noise and dispersion in precision weak lensing

Pol Gurri, Edward N. Taylor, Christopher J. Fluke

摘要:

我们分析了第一次测量精密弱透镜(PWL):一种新的方法来测量单个星系星系弱透镜通过速度信息。我们的目标是了解从PWL观察到的剪切分布,这是更广泛的比可以解释的统计测量误差。我们确定了两个可能的散射源来解释所观察到的分布:与圆形稳定旋转的基本假设相关的形状噪声项,以及与恒星-晕质量关系(SHMR)周围的对数正态色散一致的天体物理信号。我们将观察到的分布建模为这两个因素的组合,并根据我们的数据量化了它们最可能的值。对于当前样本,我们测量了$σ_γ= 0.024 \pm 0.007$的有效形状噪声,突出了该方法的低噪声影响,并将PWL定位为比传统弱透镜精确$\sim 10$倍。我们还测量了在$8.5 < \log M_\star < 11$范围内的$ξ_γ= 0.53^{+0.26}_{-0.28}$ \,dex剪切的平均分散度。该测量值高于预期,这表明晕圈质量和/或轮廓的分散度相对较高。

英文摘要:

We analyse the first measurements from precision weak lensing (PWL): a new methodology for measuring individual galaxy-galaxy weak lensing through velocity information. Our goal is to understand the observed shear distribution from PWL, which is broader than can be explained by the statistical measurement errors. We identify two possible sources of scatter to explain the observed distribution: a shape noise term associated with the underlying assumption of circular stable rotation, and an astrophysical signal consistent with a log-normal dispersion around the stellar-to-halo mass relation (SHMR). We have modelled the observed distribution as the combination of these two factors and quantified their most likely values given our data. For the current sample, we measure an effective shape noise of $σ_γ= 0.024 \pm 0.007$, highlighting the low noise impact of the method and positioning PWL as $\sim 10$ times more precise than conventional weak lensing. We also measure an average dispersion in shears of $ξ_γ= 0.53^{+0.26}_{-0.28}$\,dex over the range of $8.5 < \log M_\star < 11$. This measurement is higher than expected, which is suggestive of a relatively high dispersion in halo mass and/or profile.

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