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arXiv 1209.6590astro-ph.COgr-qc
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GRB Hubble图与Λ(t)CDM模型的约束

GRB Hubble diagram and constraints on a Λ(t)CDM model

Hermano Velten, Ariadna Montiel, Saulo Carneiro

摘要:

在以前的论文中,一个具有恒定速率粒子产生和真空项随哈勃参数线性衰减的宇宙学模型在与精确观测进行测试时显示出良好的一致性:宇宙微波背景(CMB)各向异性谱中第一个峰的位置,Ia型超新星(SNe Ia)的哈勃图,大尺度结构(LSS)的分布以及到重子声振荡(BAO)的距离。该模型与空间平坦的标准模型具有相同数量的参数,并且似乎减轻了后者出现的一些观测/理论紧张。在这封信中,我们用109个伽马射线爆发(GRB)来补充这些测试,其中59个的红移超过了$z=1.4$,这使得哈勃图的红移可以扩展到$z\approx 8$。为了用$z<1.4$校准50个伽玛暴,我们使用了斯隆数字巡天(SDSS)项目的288颗超新星,用MLCS 2k 2拟合器校准,比其他样本(如Union 2)依赖模型更少。我们的结果显示了与以前的测试,并再次,较小的紧张局势之间的Ia超新星和伽玛暴最佳拟合相比,标准模型的一个很好的一致性。

英文摘要:

In previous papers, a cosmological model with constant-rate particle creation and vacuum term decaying linearly with the Hubble parameter was shown to lead to a good concordance when tested against precise observations: the position of the first peak in the spectrum of anisotropies of the cosmic microwave background (CMB), the Hubble diagram for supernovas of type Ia (SNe Ia), the distribution of large-scale structures (LSS) and the distance to the baryonic acoustic oscillations (BAO). That model has the same number of parameters as the spatially flat standard model and seems to alleviate some observational/theoretical tensions appearing in the later. In this letter we complement those tests with 109 gamma ray bursters (GRB), 59 of them with redshifts above $z=1.4$, which permits to extend the Hubble diagram to redshifts up to $z\approx 8$. For the calibration of the 50 GRBs with $z<1.4$ we use the 288 supernovas of the Sloan Digital Sky Survey (SDSS) project, calibrated with the MLCS2k2 fitter, less model-dependent than other samples like Union2. Our results show a good concordance with the previous tests and, again, less tensions between SNe Ia and GRB best fits as compared to the standard model.

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