发表机构
University of Michigan; Boston University; Johns Hopkins University; University of Oxford（密歇根大学; 波士顿大学; 约翰斯·霍普金斯大学; 牛津大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用TITAN样本中的1086颗Ia型超新星，发现星系群内不同星系中的SN“表亲”对距离测量弥散降低30-40%，为提升距离精度提供新途径。
AI 中文摘要
在低红移处，Ia型超新星（SN Ia）哈勃图中的弥散因本动速度（PV）以及超新星距离与其宿主星系环境之间的相关性而增大，从而限制了宇宙学距离测量的精度。我们利用来自近邻宇宙ATLAS的Ia型超新星宝库（TITAN）样本中1086颗经光谱证认的SN Ia，在红移范围$0.01<z<0.05$内研究这些效应。我们识别出314颗与星系群相关的超新星，其中包括80颗发生在32个共同星系群内不同星系中的SN“表亲”。我们首先检验使用星系群中SN的群平均红移是否能减轻由本动速度引起的弥散；然而，我们发现哈勃残差弥散从使用单个宿主星系红移时的$0.184^{+0.017}_{-0.009}$星等略微增加到使用群平均红移时的$0.200^{+0.016}_{-0.015}$星等。接下来，对于SN表亲样本，我们分析其距离的成对差异，并将其弥散与完整SN样本的哈勃残差弥散进行比较。在限制表亲之间距离模数视线差异的分析变体中，我们发现SN表亲的弥散降低约30-40%，显著性为2.3-2.8$\sigma$。我们还发现初步证据表明，这些弥散差异可能由最年轻的星系群驱动，对于旋涡星系比例高的星系群，弥散降低2$\sigma$。这些结果表明，SN表亲可能为增加SN Ia距离精度和理解宿主星系及星系群属性对SN Ia距离测量的作用提供一条新途径。
英文摘要
At low redshift, scatter in the Type Ia supernova (SN Ia) Hubble diagram is increased by peculiar velocities (PVs) and correlations between SN distances and their host-galaxy environments, limiting the precision of cosmological distance measurements. We investigate these effects using 1086 spectroscopically-confirmed SNe Ia from the Type Ia Supernova Trove from ATLAS in the Nearby Universe (TITAN) sample in the redshift range $0.01<z<0.05$. We identify 314 group-associated SNe, including 80 SN "cousins" occurring in different galaxies within 32 common groups. We first examine whether using the group-averaged redshifts of SNe in galaxy groups can mitigate PV-induced scatter; however, we find that the Hubble residual scatter increases slightly from $0.184^{+0.017}_{-0.009}$ mag using individual host-galaxy redshifts to $0.200^{+0.016}_{-0.015}$ mag using group-averaged redshifts. For the sample of SN cousins, we next analyze pairwise differences in their distances and compare their scatter to the Hubble residual scatter of the full SN sample. For analysis variants that limit line-of-sight differences in distance modulus between cousins, we find $\sim$30-40% lower scatter from SN cousins at significances of 2.3-2.8$σ$. We also find tentative evidence that these differences in scatter may be driven by the youngest groups, with a 2$σ$ reduction in scatter for groups with high fractions of spiral galaxies. These results suggest that SN cousins may provide a novel route for increasing SN Ia distance precision and understanding the role of host-galaxy and group properties on SN Ia distance measurements.
Comments22 pages, 12 figures. Submitted to ApJ
