In this paper we study the possibly existing anisotropy in the acceleration expansion by use of the full sample of Union2 data. Using the hemisphere comparison method to search for a preferred direction, we take the deceleration parameter q0 as the diagnostic to quantify the anisotropy level in the wCDM model. We find that the maximum accelerating expansion direction is $(l,b)=(314_{+20^{\circ}}^{\circ-13^{\circ}},28_{+11^{\circ}}^{\circ-33^{\circ}})$,with the maximum anisotropy level of $δq_{0,max}/\bar{q}_0=0.79_{+0.27}^{-0.28}$, and that the anisotropy is more prominent when only low redshift data ($z\leq0.2$) are used. We also discuss this issue in the $CPL$ parameterized model, showing a similar result.
Redshift dependence and dipolar velocity corrections in cosmographic reconstructions through Type Ia supernova samples
Scuola Superiore Meridionale（高等南方学院）；Istituto Nazionale di Fisica Nucleare (INFN)（意大利国家核物理研究所）；Università di Camerino（卡梅里诺大学）；INAF, Osservatorio Astronomico di Brera（INAF布雷拉天文台）；INFN, Sezione di Perugia（INFN佩鲁贾分部）；Department of Nanoscale Science and Engineering, University at Albany SUNY（纽约州立大学奥尔巴尼分校纳米科学与工程系）；Al-Farabi Kazakh National University（法拉比哈萨克国立大学）；Dipartimento di Fisica, Università degli Studi di Torino（都灵大学物理系）；INFN, Sezione di Torino（INFN都灵分部）；INAF, Osservatorio Astrofisico di Torino（INAF都灵天文台）
Accelerating expansion and isotropic sky-hemisphere consistency in Pantheon+ supernovae: a revised analysis in the dark energy debate
GLA University（GLA大学）；Virtual Institute of Astroparticle physics, Paris（巴黎虚拟天体粒子物理研究所）；Jadavpur University（贾达普大学）；Indian Institute of Technology, Kanpur（坎普尔印度理工学院）；National Research Nuclear University “MEPHI”（国立研究核子大学“梅菲”）；Institute of Physics, Southern Federal University（南联邦大学物理研究所）
最近的普朗克观测证实了宇宙微波背景（CMB）辐射中的宇称违反。在本文中，我们扩展了我们以前的工作[P. Naselsky et al. Astrophys. J. { \bf 749}，31（2012）]通过考虑CMB温度各向异性的普朗克数据，对CMB宇称不对称性的方向性质进行了研究。我们定义了六种方向统计量，发现它们都表明了CMB数据的奇校验偏好。此外，我们发现所有这些统计的首选轴强烈相关的CMB运动偶极子，四极，八极的首选轴。在大于$3σ$的置信水平下证实了它们之间的对齐，这意味着CMB宇称不对称以及CMB四极和八极的异常可能具有共同的物理、污染或系统起源。此外，它们都应该与残余偶极元件的可能污染有关。
