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Local structure can have important effects on luminosity distance observations, which could for example affect the local estimation of the Hubble constant based on low red-shift type Ia supernovae. Using a spherically symmetric exact…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-18 Sergio Andrés Vallejo-Peña , Antonio Enea Romano

We study the computational complexity of determining the Hausdorff distance of two polytopes given in halfspace- or vertex-presentation in arbitrary dimension. Subsequently, a matching problem is investigated where a convex body is allowed…

Computational Geometry · Computer Science 2014-01-08 Stefan König

Based on the luminosity-distance diagram, we propose a method to quickly estimate the luminosity function for any certain astrophysical objects. Giving the mean distance between any two objects at a given luminosity range, we can find the…

Instrumentation and Methods for Astrophysics · Physics 2017-01-13 Yuan-Chuan Zou

Riemannian optimization uses local methods to solve optimization problems whose constraint set is a smooth manifold. A linear step along some descent direction usually leaves the constraints, and hence retraction maps are used to…

Statistics Theory · Mathematics 2023-01-19 Alexander Heaton , Matthias Himmelmann

We calculate the systematic inhomogeneity-induced correction to the cosmological constant that one would infer from an analysis of the luminosities and redshifts of Type Ia supernovae, assuming a homogeneous universe. The calculation…

Astrophysics · Physics 2008-12-18 R. Ali Vanderveld , Eanna E. Flanagan , Ira Wasserman

The minimum distance of a code is an important concept in information theory. Hence, computing the minimum distance of a code with a minimum computational cost is a crucial process to many problems in this area. In this paper, we present…

Information Theory · Computer Science 2024-05-01 Fernando Hernando , Francisco D. Igual , Gregorio Quintana-Ortí

We introduce two new algebraic invariants, the (co)homological distances between continuous maps, which provide computable lower bounds for the homotopic distance and strictly refine the classical cup-length estimates. We then define the…

Algebraic Topology · Mathematics 2025-11-26 Enrique Macías-Virgós , Ángel Méndez-Vázquez , David Mosquera-Lois

The luminosity distance can be used to determine the properties of large scale structure around the observer. To this purpose we develop a new inversion method to map luminosity distance to a LTB metric based on the use of the exact…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-04 Antonio Enea Romano , Hsu-Wen Chiang , Pisin Chen

In this paper, the homotopy-perturbation method (HPM) is applied to obtain approximate analytical solutions for the gravitational deflection of light in General Relativity near Schwarzschild black hole surrounded by quintessence (Kiselev…

General Relativity and Quantum Cosmology · Physics 2019-02-22 V. K. Shchigolev , D. N. Bezbatko

We re-derive a formula relating the areal and luminosity distances, entirely in the framework of the classical Maxwell theory, assuming a geometric-optics type condition.

General Relativity and Quantum Cosmology · Physics 2009-11-10 Edward Malec , Grzegorz Wylȩżek , Janusz Karkowski

The Gromov--Hausdorff distance measures the difference in shape between metric spaces and poses a notoriously difficult problem in combinatorial optimization. We introduce its quadratic relaxation over a convex polytope whose solutions…

Computational Geometry · Computer Science 2024-05-09 Vladyslav Oles

The optimal transport problem has many applications in machine learning, physics, biology, economics, etc. Although its goal is very clear and mathematically well-defined, finding its optimal solution can be challenging for large datasets…

Numerical Analysis · Mathematics 2021-12-14 Roozbeh Yousefzadeh

We study the form of the luminosity distance as a function of redshift in the presence of large scale inhomogeneities, with sizes of order 10 Mpc or larger. We approximate the Universe through the Swiss-cheese model, with each spherical…

Astrophysics · Physics 2010-10-27 N. Brouzakis , N. Tetradis , E. Tzavara

The second derivative of the luminosity distance with respect to the redshift is written in terms of the deceleration parameter $q_0$. We point out that the third derivative contains the information regarding the sound speed of cosmic…

Astrophysics · Physics 2009-10-30 Takeshi Chiba , Takashi Nakamura

We derive luminosity distance equation in Gurzadyan-Xue cosmological models and compared it with available supernovae and radio galaxies data sets. We found that the luminosity distance does not depend explicitly the speed of light and the…

Astrophysics · Physics 2010-11-11 H. G. Khachatryan , G. V. Vereshchagin , G. Yegorian

Using numerical ray tracing, the paper studies how the average distance modulus in an inhomogeneous universe differs from its homogeneous counterpart. The averaging is over all directions from a fixed observer not over all possible…

Cosmology and Nongalactic Astrophysics · Physics 2010-02-19 Valentin Kostov

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 calculation of distances is of fundamental importance in extragalactic astronomy and cosmology. However, no practical implementation for the general case has previously been available. We derive a second-order differential equation for…

Astrophysics · Physics 2016-08-30 Rainer Kayser , Phillip Helbig , Thomas Schramm

The Universe is not completely homogeneous. Even if it is sufficiently so on large scales, it is very inhomogeneous at small scales, and this has an effect on light propagation, so that the distance as a function of redshift, which in many…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 Phillip Helbig

Cosmography has been extensively utilized to constrain the kinematic state of the Universe using measured distances. In this work, we propose a new method to reconstruct coupling theories using the first kind of Chebyshev polynomial for two…

General Relativity and Quantum Cosmology · Physics 2024-12-06 Sai Swagat Mishra , N. S. Kavya , P. K. Sahoo , V. Venkatesha