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A new method is proposed to measure the Hubble constant H0 through the mean transmitted flux observed from high redshift quasars. A semi-analytical model for the cosmological-independent volume density distribution function is adopted which…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 V. C. Busti , R. N. Guimarães , J. A. S. Lima

It is well known that measurements of H0 from gravitational lens time delays scale as H0~1-k_E where k_E is the mean convergence at the Einstein radius R_E but that all available lens data other than the delays provide no direct constraints…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-19 C. S. Kochanek

The 0th, 1st and 2nd derivatives of a ``Fermat potential'' give the three D's of gravitational lensing: delay, deflection and distortion. Observations of these delays, deflections and distortions for doubly and quadruply imaged quasars give…

Astrophysics · Physics 2007-05-23 Paul L. Schechter

The cosmic curvature ($\Omega_k$) is a fundamental parameter for cosmology. In this paper, we propose an improved model-independent method to constrain the cosmic curvature, which is geometrically related to the Hubble parameter $H(z)$ and…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-07 Yuting Liu , Shuo Cao , Tonghua Liu , Xiaolei Li , Shuaibo Geng , Yujie Lian , Wuzheng Guo

The increase of discrepancy in the standard procedure to choose the arbitrary functional form of the Lagrangian $f(Q)$ motivates us to solve this issue in modified theories of gravity. In this regard, we investigate the Gaussian process…

General Relativity and Quantum Cosmology · Physics 2024-09-06 Gaurav N. Gadbail , Sanjay Mandal , P. K. Sahoo

In this paper, we present a model-independent approach to calibrate the largest quasar sample. Calibrating quasar samples is essentially constraining the parameters of the linear relation between the $\log$ of the ultraviolet (UV) and X-ray…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-11 Xiaolei Li , Ryan E. Keeley , Arman Shafieloo , Xiaogang Zheng , Shuo Cao , Marek Biesiada , Zong-Hong Zhu

The use of Gaussian Processes with a measurement of the cosmic expansion rate based solely on the observation of cosmic chronometers provides a completely cosmology-independent reconstruction of the Hubble constant H(z) suitable for testing…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-21 Fulvio Melia , Manoj K. Yennapureddy

We introduce a novel way of measuring $H_0$ from a combination of independent geometrical datasets, with no need of calibration nor of the choice of a cosmological model. We build on the {\it distance duality relation} which sets the ratio…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-20 Fabrizio Renzi , Alessandra Silvestri

The current accelerated expansion of the Universe remains ones of the most intriguing topics in modern cosmology, driving the search for innovative statistical techniques. Recent advancements in machine learning have significantly enhanced…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-03 José de Jesús Velázquez , Luis A. Escamilla , Purba Mukherjee , J. Alberto Vázquez

Gaussian processes provide a method for extracting cosmological information from observations without assuming a cosmological model. We carry out cosmography -- mapping the time evolution of the cosmic expansion -- in a model-independent…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-11 Arman Shafieloo , Alex G. Kim , Eric V. Linder

We present a simple mass model for the lensing galaxy in the gravitationally lensed quasar 0957+561. The model is a generalization of the singular isothermal sphere and includes a core radius, $r_c$, and a power-law index, $\eta$, defined…

Astrophysics · Physics 2009-10-28 Norman A. Grogin , Ramesh Narayan

Time delay in galaxy gravitational lensing systems has been used to determine the value of Hubble constant. As in other dynamical phenomena at the scale of galaxy, dark matter is often invoked in gravitational lensing to account for the…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-10 Yong Tian , Chung-Ming Ko , Mu-Chen Chiu

We present a unified Bayesian framework to jointly constrain the Hubble constant $H_0$ and the post-Newtonian parameter $\gamma$, a key probe of deviations from general relativity, using the population characteristics of strongly lensed…

General Relativity and Quantum Cosmology · Physics 2025-05-15 Xinguang Ying , Tao Yang

The cosmic curvature, a fundamental parameter for cosmology could hold deep clues to inflation and cosmic origins. We propose an improved model-independent method to constrain the cosmic curvature by combining the constructed Hubble diagram…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-19 Tonghua Liu , Shuo Cao , Jia Zhang , Marek Biesiada , Yuting Liu , Yujie Lian

The Hubble constant ($H_{0}$) is a measurement to describe the expansion rate of the Universe in the current era. However, there is a $4.4\sigma$ discrepancy between the measurements from the early Universe and the late Universe. In this…

Strong gravitational lens systems with time delays between the multiple images allow measurements of time-delay distances, which are primarily sensitive to the Hubble constant that is key to probing dark energy, neutrino physics, and the…

For 100 years since galaxies were found to be flying apart from each other, astronomers have been trying to determine how fast. The expansion, characterized by the Hubble constant, H0, is confused locally by peculiar velocities caused by…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-23 R. Brent Tully

EDITED FROM PAPER: We present mass models of the four-image gravitational lens system B1608+656. A mass model for the lens galaxies has been determined that reproduces the image positions, two out of three flux-density ratios and the model…

Astrophysics · Physics 2009-10-31 L. V. E. Koopmans , C. D. Fassnacht

Accurate and precise measurements of the Hubble constant are critical for testing our current standard cosmological model and revealing possibly new physics. With Hubble Space Telescope (HST) imaging, each strong gravitational lens system…

The Hubble tension has become one of the central problems in cosmology. In this work, we determine the Hubble constant $H_0$ and sound horizon $r_d$ by using the combination of Baryon Acoustic Oscillations (BAOs) from DESI surveys,…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-06 Zhiwei Yang , Tonghua Liu , Xiaolei Li