19 pages, 9 figures, 7 tables, published in Astronomy & Astrophysics in January 2022, Volume 657, Page A133, accepted for publication on 12 October 2021. v2: changes after refereeing process
We tested whether refracted gravity, a theory of modified gravity that describes the dynamics of galaxies without the aid of dark matter, can model the dynamics of the three massive elliptical galaxies, NGC 1407, NGC 4486, and NGC 5846, out to $\sim$$10R_{\rm e}$, where the baryonic mass component fades out and dark matter is required in Newtonian gravity. We probed these outer regions with the kinematics of the globular clusters provided by the SLUGGS survey. Refracted gravity mimics dark matter with the gravitational permittivity, a monotonic function of the local mass density depending on three parameters, $ε_0$, $ρ_{\rm c}$, and $Q$, which are expected to be universal. Refracted gravity satisfactorily reproduces the velocity dispersion profiles of the stars and red and blue globular clusters, with stellar mass-to-light ratios in agreement with stellar population synthesis models, and orbital anisotropy parameters consistent with previous results obtained in Newtonian gravity with dark matter. The sets of the three parameters of the gravitational permittivity found for each galaxy are consistent with each other within $\sim$2$σ$. We compare the mean $\{ε_0,Q,\log_{10}\left[ρ_{\rm c}\left(\mathrm{g}\, \mathrm{cm}^{-3}\right)\right]\} = \{0.089^{+0.038}_{-0.035}, 0.47^{+0.29}_{-0.21}, -24.25^{+0.28}_{-0.20}\}$ found here with the means of the parameters required to model the rotation curves and vertical velocity dispersion profiles of 30 disk galaxies from the DiskMass Survey (DMS): $ρ_{\rm c}$ and $Q$ agree within 1$σ$ with the DMS values, whereas $ε_0$ agrees within 3$σ$. This agreement suggests that ellipticals and disk galaxies allow for common values of the parameters of the permittivity and supports the universality of the permittivity function.
Dark Coincidences: Small-Scale Solutions with Refracted Gravity and MOND
广义相对论及其牛顿弱场极限不足以解释宇宙中观察到的现象，从大尺度结构的形成到星系的动力学，只有重子物质存在。研究最多的宇宙学模型$Λ$ CDM通过引入暗能量和暗物质这两个暗分量来解释大部分观测结果，这两个暗分量代表了宇宙质量-能量预算的95%，即$\sim$。然而，$Λ$ CDM模型在星系尺度上面临着重要的挑战。例如，盘星系中暗物质和重子物质的性质之间的一些非常紧密的关系，如重子Tully-Fisher关系（BTFR）、质量离散-加速度关系（MDAR）和径向加速度关系（RAR），它们见证了加速度标度$a_0 \simeq 1.2 \times 10^{-10}$ m s $^{-2}$的出现，不能用CDM范式直观地解释，宇宙结构通过随机合并过程形成。一个更突出的巧合是，星系动力学产生的加速度标度$a_0$似乎也与宇宙学常数$Λ$有关。另一个挑战是矮星系，它们比最里面的区域预期的要暗。这些证据可以更自然地解释，或者有时甚至预测，通过修改的引力理论，不引入任何暗流体。我用修改后的重力理论MOND来说明这些问题的可能解决方案，该理论在加速度小于$a_0$的情况下偏离牛顿重力，并用折射重力来说明这些问题，折射重力是2016年引入的一种新的经典重力理论，其中重力定律的修改由密度尺度来调节。
Searching for Nearby Supermassive Black Hole Binaries with GRAVITY
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Cité（巴黎天文台 LESIA，巴黎文理研究大学，法国国家科学研究中心，索邦大学，巴黎西岱大学）；Faculdade de Engenharia, Universidade do Porto（波尔图大学工程学院）；CENTRA - Centro de Astrofísica e Gravitação, IST, Universidade de Lisboa（里斯本大学理工学院 CENTRA 天体物理与引力中心）；European Southern Observatory（欧洲南方天文台）；Univ. Grenoble Alpes, CNRS, IPAG（格勒诺布尔阿尔卑斯大学，法国国家科学研究中心，IPAG）；Max-Planck-Institut für extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；Max-Planck-Institut für Astronomie (MPIA)（马克斯·普朗克天文学研究所）；INAF - Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所）；Institute of Astronomy, KU Leuven（鲁汶大学天文学研究所）
DGSAT: Dwarf Galaxy Survey with Amateur Telescopes II. A catalogue of isolated nearby edge-on disk galaxies and the discovery of new low surface brightness systems
