利用来自暗能量巡天的Ia型超新星的首次宇宙学结果：宿主星系性质对超新星亮度的影响
First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: The Effect of Host Galaxy Properties on Supernova Luminosity
摘要：
我们提出了改进的光度测量的主机星系的206光谱证实Ia型超新星发现的暗能量调查超新星计划（DES-SN），并在第一次DES-SN宇宙学分析。拟合光谱能量分布的$griz$测光测量的DES-SN的宿主星系，我们得到恒星质量和恒星形成率。对于DES-SN样本，当考虑5D（$z$，$x_1$，$c$，$α$，$β$）偏差校正，我们发现哈勃残余“质量阶跃”的证据，在大质量星系中的超新星Ia（$>10^{10} \textrm{M}_{\odot}$）本质上更明亮（校正后）通过$γ=0.040\pm0.019$ MAG测量其低质量对应物。该值比第一次DES中发现的值大$0.031$ MAG。SN宇宙学分析。这种差异是由于更新的光度测量和改进的恒星形成历史相结合，而不是从主星系的错误识别。当使用一个一维（仅红移）的偏差校正推断的质量步骤是较大的，与$γ=0.066\pm0.020$马格。的1D-5D $γ$差异DES-SN是$0.026\pm0.009$马格。我们表明，这种差异是由于宿主星系恒星质量和$x_1$组件的5D距离偏差校正之间的强相关性。为了更好地理解这种效应，我们在模拟的超新星Ia样本中包含了光变曲线宽度和恒星质量之间的内在相关性。我们表明，与1D拟合的$+2$ mmag偏倚相比，5D拟合恢复了具有$-9$ mmag偏倚的$γ$。这种差异可以解释数据中出现的部分差异。改进星系属性和SN之间的相关性建模是必要的，以确定$γ$的影响，并确保无偏的精确估计的暗能量状态方程，因为我们进入LSST的时代。
英文摘要：
We present improved photometric measurements for the host galaxies of 206 spectroscopically confirmed type Ia supernovae discovered by the Dark Energy Survey Supernova Program (DES-SN) and used in the first DES-SN cosmological analysis. Fitting spectral energy distributions to the $griz$ photometric measurements of the DES-SN host galaxies, we derive stellar masses and star-formation rates. For the DES-SN sample, when considering a 5D ($z$, $x_1$, $c$, $α$, $β$) bias correction, we find evidence of a Hubble residual `mass step', where SNe Ia in high mass galaxies ($>10^{10} \textrm{M}_{\odot}$) are intrinsically more luminous (after correction) than their low mass counterparts by $γ=0.040\pm0.019$mag. This value is larger by $0.031$mag than the value found in the first DES-SN cosmological analysis. This difference is due to a combination of updated photometric measurements and improved star formation histories and is not from host-galaxy misidentification. When using a 1D (redshift-only) bias correction the inferred mass step is larger, with $γ=0.066\pm0.020$mag. The 1D-5D $γ$ difference for DES-SN is $0.026\pm0.009$mag. We show that this difference is due to a strong correlation between host galaxy stellar mass and the $x_1$ component of the 5D distance-bias correction. To better understand this effect, we include an intrinsic correlation between light-curve width and stellar mass in simulated SN Ia samples. We show that a 5D fit recovers $γ$ with $-9$mmag bias compared to a $+2$mmag bias for a 1D fit. This difference can explain part of the discrepancy seen in the data. Improvements in modeling correlations between galaxy properties and SN is necessary to determine the implications for $γ$ and ensure unbiased precision estimates of the dark energy equation-of-state as we enter the era of LSST.
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