Dark Energy at early times and ACT: a larger Hubble constant without late-time priors
Vivian Poulin, Tristan L. Smith, Alexa Bartlett
备注：
20 pages, 15 figures, comments welcome; v2: corrected minor typos, added references, updated results and discussion of NEDE, new appendices on ACT vs. ACT+WMAP residuals and the chi-squared per experiment; conclusions unchanged
In this paper we fit two models of Early Dark Energy (EDE) (an increase in the expansion rate before recombination) to the combination of Atacama Cosmology Telescope (ACT) measurements of the Cosmic Microwave Background (CMB) with data from either the WMAP or the Planck satellite, along with measurements of the baryon acoustic oscillations and uncalibrated supernovae luminosity distance. We study a phenomenological axion-like potential ('axEDE') and a scalar field experiencing a first-order phase-transition ('NEDE'). We find that for both models the 'Planck-free' analysis yields non-zero EDE at > 2 sigma and an increased value for $H_0 \sim 70-74$ km/s/Mpc, compatible with local measurements, without the inclusion of any prior on $H_0$. On the other hand, the inclusion of Planck data restricts the EDE contribution to an upper-limit only at 95% C.L. For axEDE, the combination of Planck and ACT leads to constraints 30% weaker than with Planck alone, and there is no residual Hubble tension. On the other hand, NEDE is more strongly constrained in a Planck+ACT analysis, and the Hubble tension remains at $\sim 3σ$, illustrating the ability for CMB data to distinguish between EDE models. We explore the apparent inconsistency between the Planck and ACT data and find that it comes (mostly) from a slight tension between the temperature power spectrum at multipoles around $\sim 1000$ and $\sim 1500$. Finally, through a mock analysis of ACT data, we demonstrate that the preference for EDE is not driven by a lack of information at high-$\ell$ when removing Planck data, and that a LCDM fit to the fiducial EDE cosmology results in a significant bias on $\{H_0,ω_{\rm cdm}\}$. More accurate measurements of the TT power spectra above $\ell\sim 2500$ and EE between $\ell \sim 300-500$ will play a crucial role in differentiating EDE models.
The isotropy of Hubble expansion in the early and late Universe
University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理研究所）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；Duke University（杜克大学）
Can Distance Duality Violation Save Late-time Solutions to the Hubble Tension?
Institute of Theoretical Physics, Chinese Academy of Sciences (CAS)（中国科学院理论物理研究所）；Raman Research Institute（拉曼研究所）；Department of Physics, Indian Institute of Science（印度科学理工学院物理系）；Asia Pacific Center for Theoretical Physics (APCTP)（亚太理论物理中心）；Laboratoire Univers & Particules de Montpellier, CNRS & Université de Montpellier (UMR-5299)（蒙彼利埃宇宙与粒子实验室，法国国家科学研究中心与蒙彼利埃大学）
National Technical University of Athens（雅典国立技术大学）；Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens（雅典国家天文台天体物理学、空间应用与遥感研究所）；Universidad Católica del Norte（北天主教学会大学）；CAS Key Laboratory for Researches in Galaxies and Cosmology, School of Astronomy and Space Science, University of Science and Technology of China（中国科学院星系与宇宙学重点实验室，中国科学技术大学天文与空间科学学院）
Ningbo University（宁波大学）；Institute of Theoretical Physics, Chinese Academy of Sciences (CAS)（中国科学院理论物理研究所）；Asia Pacific Center for Theoretical Physics (APCTP)（亚太理论物理中心）
The late afterglow of GW170817/GRB170817A: a large viewing angle and the shift of the Hubble constant to a value more consistent with the local measurements
Hubble constant and sound horizon from the late-time Universe
我们利用低红移数据测量了近代宇宙的膨胀率和重子声振荡（BAO）的刻度。BAO依赖于校准标度，即，拖曳期$r_d$结束时的声视界，这通常会对普朗克卫星的宇宙微波背景（CMB）测量产生影响。为了对$H_0$进行真正独立的测量，我们将$r_d$完全免费，并使用BAO数据集与31个观测数据$H(z)$，GW 170817和Ia型超新星的Pantheon样本相结合。在$Λ$ CDM模型中，我们得到了$H_0=68.63^{+1.75}_{-1.77}$ km s $^{-1}$ Mpc $^{-1}$，$r_d=146.85^{+3.29}_{-3.77}$ Mpc.对于$H(z)$的两个模型无关重建，我们得到了三次展开的$H_0=68.02\pm1.82$ km s $^{-1}$ Mpc $^{-1}$，$r_d=148.18^{+3.36}_{-3.78}$ Mpc和多项式展开的$H_0=68.58\pm1.76$ km s $^{-1}$ Mpc $^{-1}$，$r_d=148.02^{+3.63}_{-3.60}$ Mpc.哈勃常数$H_0$和声音视界$r_d$的值与假设平坦$Λ$ CDM模型的普朗克CMB数据得出的估计一致，但$H_0$分别与SH0 ES 2019处于$2.4\sim2.6$ $σ$张力中。
Hubble tension in k-essence: Evidence for robust tension alleviation
Botswana International University of Science and Technology（博茨瓦纳国际科学与技术大学）；University of Cape Town（开普敦大学）；North-West University（西北大学）；Omdurman Islamic University（恩图曼伊斯兰大学）
Revisiting the Matter Creation Process: Observational Constraints on Gravitationally Induced Dark Energy and the Hubble Tension
SISSA-International School for Advanced Studies（国际高等研究学院）；INFN, Sezione di Trieste（意大利国家核物理研究所的里雅斯特分部）；Institute of Space Sciences (ICE,CSIC)（空间科学研究所）；Universidad Complutense de Madrid（马德里康普顿斯大学）；Istanbul Technical University（伊斯坦布尔理工大学）；ENEA, Nuclear Department（意大利国家新能源与可再生能源署核能部）；Sapienza University of Rome（罗马智慧大学）；University of Sheffield（谢菲尔德大学）
Dynamical Dark Energy and the Unresolved Hubble Tension: Multi-model Constraints from DESI 2025 and Other Probes
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；College of Astronomy and Space Sciences, University of Chinese Academy of Sciences（中国科学院大学天文学与空间科学学院）；School of Physics and Astronomy, Sun Yat-Sen University（中山大学物理学院）
