Increasing Neff with particles in thermal equilibrium with neutrinos
Increasing Neff with particles in thermal equilibrium with neutrinos
复制标题
增加与中微子热平衡的粒子的 Neff
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
C. McCabe
中科院分区：
文献类型：
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作者：
C. Boehm;M. Dolan;C. McCabe
最近关于增加早期宇宙中中微子种类（Neff）的有效数量的工作集中在引入额外的相对论性种类（“暗辐射”）。我们提请注意另一种可能性：一种质量为10 MeV的新粒子，它与中微子保持热平衡，直到它变得非相对论性，增加了中微子相对于光子的温度。我们证明，这导致一个值的Neff是大于3，在CMB形成的Neff是大于在BBN。我们调查这些粒子的约束，从原始丰度的氦和氘在BBN和从CMB功率谱ACT和SPT测量，发现他们目前相对不受约束。我们预测了普朗克卫星对这种情况的敏感性：除了极大地改善对粒子质量的约束外，在参数空间的某些区域，它还可以区分新粒子是真实的标量还是复标量。
Recent work on increasing the effective number of neutrino species (Neff) in the early universe has focussed on introducing extra relativistic species ('dark radiation'). We draw attention to another possibility: a new particle of mass 10 MeV that remains in thermal equilibrium with neutrinos until it becomes non-relativistic increases the neutrino temperature relative to the photons. We demonstrate that this leads to a value of Neff that is greater than three and that Neff at CMB formation is larger than at BBN. We investigate the constraints on such particles from the primordial abundance of helium and deuterium created during BBN and from the CMB power spectrum measured by ACT and SPT and find that they are presently relatively unconstrained. We forecast the sensitivity of the Planck satellite to this scenario: in addition to dramatically improving constraints on the particle mass, in some regions of parameter space it can discriminate between the new particle being a real or complex scalar.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.