Strongly lensed explosive transients such as supernovae, gamma-ray bursts, fast radio bursts, and gravitational waves are very promising tools to determine the Hubble constant (H0) in the near future in addition to strongly lensed quasars. In this work, we show that the transient nature of the point source provides an advantage over quasars: The lensed host galaxy can be observed before or after the transient’s appearance. Therefore, the lens model can be derived from images free of contamination from bright point sources. We quantify this advantage by comparing the precision of a lens model obtained from the same lenses with and without point sources. Based on Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations with the same sets of lensing parameters, we simulate realistic mock data sets of 48 quasar lensing systems (i.e. adding AGN in the galaxy centre) and 48 galaxy–galaxy lensing systems (assuming the transient source is not visible but the time delay and image positions have been or will be measured). We then model the images and compare the inferences of the lens model parameters and H0. We find that the precision of the lens models (in terms of the deflector mass slope) is better by a factor of 4.1 for the sample without lensed point sources, resulting in an increase of H0 precision by a factor of 2.9. The opportunity to observe the lens systems without the transient point sources provides an additional advantage for time-delay cosmography over lensed quasars. It facilitates the determination of higher signal-to-noise stellar kinematics of the main deflector, and thus its mass density profile, which, in turn plays a key role in breaking the mass-sheet degeneracy and constraining H0.

中文翻译：

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改进了瞬态源的延时镜头建模和 H0 推理

除了强透镜类星体之外，强透镜爆炸瞬变，如超新星、伽马射线爆发、快速射电暴和引力波，是在不久的将来确定哈勃常数 (H0) 的非常有前途的工具。在这项工作中，我们表明点源的瞬态特性提供了优于类星体的优势：可以在瞬态出现之前或之后观察到带透镜的宿主星系。因此，镜头模型可以从不受亮点源污染的图像中推导出来。我们通过比较从具有和不具有点源的相同镜头获得的镜头模型的精度来量化这一优势。基于哈勃太空望远镜 (HST) 宽视场相机 3 (WFC3) 的观测，使用相同的透镜参数集，我们模拟了 48 个类星体透镜系统的真实模拟数据集（即 在星系中心添加 AGN）和 48 个星系-星系透镜系统（假设瞬态源不可见，但已经或将测量时间延迟和图像位置）。然后我们对图像进行建模并比较镜头模型参数和 H0 的推论。我们发现，对于没有透镜点源的样本，透镜模型的精度（就偏转器质量斜率而言）提高了 4.1 倍，导致 H0 精度提高了 2.9 倍。在没有瞬态点源的情况下观察透镜系统的机会为时间延迟宇宙学提供了额外的优势，而不是透镜类星体。它有助于确定主偏转器的更高信噪比恒星运动学，从而确定其质量密度分布，其中，