The BAO+BBN take on the Hubble tension
The BAO+BBN take on the Hubble tension
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DOI：
10.1088/1475-7516/2019/10/029
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发表时间：
2019-07
影响因子：
6.4
通讯作者：
Nils Schöneberg;J. Lesgourgues;D. C. Hooper
中科院分区：
文献类型：
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作者：
Nils Schöneberg;J. Lesgourgues;D. C. Hooper
许多试图用扩展的宇宙学模型来解决哈勃张力的尝试都是将联合收割机与影响宇宙学扰动演化的新物理成分结合起来，在背景宇宙学的水平上增强遗迹辐射密度。几位作者指出，结合重子声振荡（BAO）和大爆炸核合成（BBN）数据，可以独立于CMB图和超新星数据来探测背景宇宙学历史。使用BBN的最新假设，我们证实，在3.2σ水平下，在ΛCDM假设下，组合的BAO，氘和氦数据与SH0ES测量值处于紧张状态，同时与CMB值接近一致。我们随后表明，浮动的辐射密度参数Neff只减少了张力下降到2.6σ的水平。这一结论完全独立于任何CMB数据，表明高Neff解释额外的遗迹（自由流或自相互作用）并不能为危机提供明显的解决方案，即使在背景宇宙学的水平上也是如此。为了规避这种强约束，（i）额外的辐射必须在BBN之后产生，以避免氦约束，以及（ii）必须在扰动水平上调用额外的成分，以使这种额外的辐射与CMB和LSS数据相一致。
Many attempts to solve the Hubble tension with extended cosmological models combine an enhanced relic radiation density, acting at the level of background cosmology, with new physical ingredients affecting the evolution of cosmological perturbations. Several authors have pointed out the ability of combined Baryon Acoustic Oscillation (BAO) and Big Bang Nucleosynthesis (BBN) data to probe the background cosmological history independently of both CMB maps and supernovae data. Using state-of-the-art assumptions on BBN, we confirm that combined BAO, deuterium, and helium data are in tension with the SH0ES measurements under the ΛCDM assumption at the 3.2σ level, while being in close agreement with the CMB value. We subsequently show that floating the radiation density parameter Neff only reduces the tension down to the 2.6σ level. This conclusion, totally independent of any CMB data, shows that a high Neff accounting for extra relics (either free-streaming or self-interacting) does not provide an obvious solution to the crisis, not even at the level of background cosmology. To circumvent this strong bound, (i) the extra radiation has to be generated after BBN to avoid helium bounds, and (ii) additional ingredients have to be invoked at the level of perturbations to reconcile this extra radiation with CMB and LSS data.