论文标题
首先看一下与JWST的SN IA主持人中的Cepheids
A First Look at Cepheids in a SN Ia Host with JWST
论文作者
论文摘要
我们报告了詹姆斯·韦伯（James Webb）空间望远镜的首次查看，该变量是从偶然的（为此目的）观察NGC 1365（SN IA的宿主）（SN IA（SN 2012FR），这是一种用于测量Hubble常数的校准路径）。如预期的那样，与在相似的近红外波长处相比，使用NIRCAM通过NIRCAM到F200W的高分辨率观察显示，与HST图像相比，与HST图像相比，该光谱区域已用于减轻宿主粉尘对距离测量的影响。使用标准星P330E作为Zeropoint和PSF参考，我们在JWST字段中摄影31个先前已知的头孢虫，跨越1.15 <log P <1.75，包括1.35 <log p <1.75的长期间隔，包括24个头孢菌素。我们将所得的周期 - 亮度关系与整个周期范围内的49个头孢虫的关系进行了比较，其中包括在HST上使用WFC3/IR观察到的较长周期范围，并转换为JWST光度法系统（F200W，VEGA）。 HST和JWST的两个空间望远镜测量的P-L关系非常吻合，分别为25.74 +/- 0.04和25.72+-0.05，截距（log p = 1）为25.74 +/- 0.05。我们的基线结果来自较长的周期范围，在该范围内，头孢虫具有较高的信噪比，在该范围内，我们发现HST和JWST分别为25.75+\ -0.05和25.75+\ -0.06 mag。我们发现第一个JWST测量和HST之间的良好一致性，并且没有证据表明HST CepheID光度法在〜0.2 mag级别上是“有偏见的明亮”，尽管保证和预期，但需要减轻Hubble张力就需要缓解哈勃张力。我们预计未来的JWST观察结果将超过这些观察，因为它们将被优化用于测量头孢虫。
We report the first look at extragalactic Cepheid variables with the James Webb Space Telescope, obtained from a serendipitous (to this purpose) observation of NGC 1365, host of an SN Ia (SN 2012fr), a calibration path used to measure the Hubble constant. As expected, the high-resolution observations with NIRCam through F200W show better source separation from line-of-sight companions than HST images at similar near-infrared wavelengths, the spectral region that has been used to mitigate the impact of host dust on distance measurements. Using the standard star P330E as a zeropoint and PSF reference, we photometered 31 previously-known Cepheids in the JWST field, spanning 1.15 < log P < 1.75 including 24 Cepheids in the longer period interval of 1.35 < log P < 1.75. We compared the resultant Period-Luminosity relations to that of 49 Cepheids in the full period range including 38 in the longer period range observed with WFC3/IR on HST and transformed to the JWST photometric system (F200W, Vega). The P-L relations measured with the two space telescopes are in good agreement, with intercepts (at log P=1) of 25.74+/-0.04 and 25.72+\-0.05 for HST and JWST, respectively. Our baseline result comes from the longer period range where the Cepheids have higher signal-to-noise ratios where we find 25.75+\-0.05 and 25.75+\-0.06 mag for HST and JWST, respectively. We find good consistency between this first JWST measurement and HST, and no evidence that HST Cepheid photometry is "biased bright" at the ~0.2 mag level that would be needed to mitigate the Hubble Tension, though comparisons from more SN hosts are warranted and anticipated. We expect future JWST observations to surpass these in quality as they will be optimized for measuring Cepheids.
