Distance measurements from supernovae and dark energy constraints
Distance measurements from supernovae and dark energy constraints
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DOI：
10.1103/physrevd.80.123525
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发表时间：
2009-10
影响因子：
5
通讯作者：
Yun Wang
中科院分区：
文献类型：
--
作者：
Yun Wang
当前观测数据对暗能量的限制对如何从Ia型超新星(SNIa)数据测量距离很敏感。我们发现，SNE Ia的通量平均可以用来检验未知系统不确定性的存在，并产生来自SNE Ia的更稳健的距离测量。我们已经将这种方法应用于288个SNE Ia的$\mathrm{\text{nearby}}+\mathrm{SDSS}+\mathrm{ESSENCE}+\mathrm{SNLS}+\mathrm{HST}$集合和397个SNE Ia的“宪法”集合。结合Sn Ia数据和来自Wilkinson微波各向异性探测器5年观测的宇宙微波背景各向异性数据、斯隆数字天空探测重子声振荡测量、69个伽马射线暴(GRB)的数据以及哈勃望远镜项目的哈勃常数测量，我们测量了暗能量密度函数$X(z)\ensuremath{\equiv}{\ensuremath{\rho}}_{X}(z)/{\ensuremath{\rho}}_{X}(0)$作为红移的自由函数(假设在$Zg1或$Zg1.5$处为常数)。在没有SNE Ia通量平均化的情况下，使用SNE Ia组成集的组合数据似乎表明，在$0\ensuremath{\lesssim}z\ensuremath{\lesssim}0.8$；，当SNE Ia通量平均化时，宇宙常数偏离了95%置信度的宇宙学常数，与68%置信度的宇宙学常数一致。使用SNE Ia的$\mathrm{\text{nearby}}+\mathrm{SDSS}+\mathrm{ESSENCE}+\mathrm{SNLS}+\mathrm{HST}$数据集的组合数据在考虑或不考虑SNE Ia通量平均的情况下与68%置信度的宇宙学常数是一致的，并且给出了比使用SNE Ia的组成集更严格的暗能量约束。假设宇宙是平的，使用来自$\mathrm{\text{nearby}}+\mathrm{SDSS}+\mathrm{ESSENCE}+\mathrm{SNLS}+\mathrm{HST}$，的288SNE Ia的组合数据，暗能量被检测到$g98%的置信度水平，而与关于$X(z确保数学1)$的假设无关。我们使用X(Z)$的暗能量优值系数和宇宙标度因子中的线性暗能量状态方程来量化暗能量约束，而不假设宇宙是平坦的。
Constraints on dark energy from current observational data are sensitive to how distances are measured from Type Ia supernova (SN Ia) data. We find that flux averaging of SNe Ia can be used to test the presence of unknown systematic uncertainties, and yield more robust distance measurements from SNe Ia. We have applied this approach to the $\mathrm{\text{nearby}}+\mathrm{SDSS}+\mathrm{ESSENCE}+\mathrm{SNLS}+\mathrm{HST}$ set of 288 SNe Ia, and the ``Constitution'' set of 397 SNe Ia. Combining the SN Ia data with cosmic microwave background anisotropy data from Wilkinson Microwave Anisotropy Probe 5 yr observations, the Sloan Digital Sky Survey baryon acoustic oscillation measurements, the data of 69 gamma-ray bursts (GRBs) , and the Hubble constant measurement from the Hubble Space Telescope project SHOES, we measure the dark energy density function $X(z)\ensuremath{\equiv}{\ensuremath{\rho}}_{X}(z)/{\ensuremath{\rho}}_{X}(0)$ as a free function of redshift (assumed to be a constant at $zg1$ or $zg1.5$). Without the flux averaging of SNe Ia, the combined data using the Constitution set of SNe Ia seem to indicate a deviation from a cosmological constant at $\ensuremath{\sim}95%$ confidence level at $0\ensuremath{\lesssim}z\ensuremath{\lesssim}0.8$; they are consistent with a cosmological constant at $\ensuremath{\sim}68%$ confidence level when SNe Ia are flux averaged. The combined data using the $\mathrm{\text{nearby}}+\mathrm{SDSS}+\mathrm{ESSENCE}+\mathrm{SNLS}+\mathrm{HST}$ data set of SNe Ia are consistent with a cosmological constant at 68% confidence level with or without flux averaging of SNe Ia, and give dark energy constraints that are significantly more stringent than that using the Constitution set of SNe Ia. Assuming a flat Universe, dark energy is detected at $g98%$ confidence level for $z\ensuremath{\le}0.75$ using the combined data with 288 SNe Ia from $\mathrm{\text{nearby}}+\mathrm{SDSS}+\mathrm{ESSENCE}+\mathrm{SNLS}+\mathrm{HST}$, independent of the assumptions about $X(z\ensuremath{\ge}1)$. We quantify dark energy constraints without assuming a flat Universe using the dark energy figure of merit for both $X(z)$ and a dark energy equation-of-state linear in the cosmic scale factor.