Gravitational Redshift Experiment with the Space Radio Telescope RadioAstron

Testing the Einstein Equivalence Principle with two Earth-orbiting clocks

We consider the problem of testing the Einstein Equivalence Principle (EEP) by measuring the gravitational redshift with two Earth-orbiting stable atomic clocks. For a reasonably restricted class of orbits we find an optimal experiment configuration that provides for the maximum accuracy of measuring the relevant EEP violation parameter. The perigee height of such orbits is $\sim$~1,000~km and the period is 3--5~hr, depending on the clock type. For the two of the current best space-qualified clocks, the VCH-1010 hydrogen maser and the PHARAO cesium fountain clock, the achievable experiment acc…

Redshift drift in a pressure-gradient cosmology

We derive a redshift drift formula for the spherically symmetric inhomogeneous pressure Stephani universes which are complementary to the spherically symmetric inhomogeneous density Lemaître-Tolman-Bondi models. We show that there is a clear difference between redshift drift predictions for these two models as well as between the Stephani models and the standard $Λ$CDM Friedmann models. The Stephani models have positive drift values at small redshift and behave qualitatively (but not quantitatively) as the $Λ$CDM models at large redshift, while the drift for LTB models is always negative. This…

Cosmology with the Einstein Telescope: No Slip Gravity Model and Redshift Specifications

The Einstein Telescope and other third generation interferometric detectors of gravitational waves are projected to be operational post $2030$. The cosmological signatures of gravitational waves would undoubtedly shed light on any departure from the current gravitational framework. We here confront a specific modified gravity model, the No Slip Gravity model, with forecast observations of gravitational waves. We compare the predicted constraints on the dark energy equation of state parameters $w_0^{}-w_a^{}$, between the modified gravity model and that of Einstein gravity. We show that the No …

利用爱因斯坦望远镜联合估计宇宙学模型及双黑洞族的质量与红移分布

Joint estimation of the cosmological model and the mass and redshift distributions of the binary black hole population with the Einstein Telescope

本研究利用爱因斯坦望远镜一年模拟观测数据，通过分层贝叶斯框架联合估计宇宙学模型与双黑洞族的质量、红移分布，分析了不同SNR阈值下的参数约束精度与简并性，明确了一年观测对质量分布的重构能力及红移分布的约束局限。

利用爱因斯坦望远镜对高红移源进行快速准确的参数估计

Fast and accurate parameter estimation of high-redshift sources with the Einstein Telescope

针对爱因斯坦望远镜海量高红移引力波事件参数估计的效率瓶颈，本研究采用基于Dingo-IS的神经后验估计方法，实现快速准确的参数推断，验证了其相比费希尔信息矩阵方法的精度优势。

Constraining parameters of coalescing stellar mass binary black hole systems with the Einstein Telescope alone

The Einstein Telescope (ET) is the future third generation gravitational wave detector consisting of three independent interferometers arranged in a triangular configuration, with the sensitivity large enough to be able to detect stellar mass black holes even beyond the redshift of 10. In this paper, we analyze the capabilities of ET as a standalone instrument and not part of a network. We show that the analysis of detection of binary coalescences in the three individual interferometers of the ET allow us to weakly constrain the sky location of the source. We present the analysis that leads to…

Are High-Redshift Quasars Blurry?

It has been suggested that the fuzzy nature of spacetime at the Planck scale may cause lightwaves to lose phase coherence, and if severe enough this could blur images of distant point-like sources sufficiently that they do not form an Airy pattern at the focal plane of a telescope. Blurring this dramatic has already been observationally ruled out by images from Hubble Space Telescope (HST), but I show that the underlying phenomenon could still be stronger than previously considered. It is harder to detect, which may explain why it has gone unseen. A systematic search is made in archival HST im…