Code Monkey home page Code Monkey logo

h0_tension_data's Introduction

H0 Tension, Phantom Dark Energy and Cosmological Parameter Degeneracies

Travis

This is the repository that contains the Mathematica code as well as useful comments that reproduce the figures of arxiv:2004.08363.

Abstract

Phantom dark energy ($w<-1$) can produce amplified cosmic acceleration at late times, thus increasing the value of $H_0$ favored by CMB data and releasing the tension with local measurements of $H_0$. We show that the best fit value of $H_0$ in the context of the CMB power spectrum is degenerate with a constant equation of state parameter $w$, in accordance with the approximate effective linear equation $H_0 + 30.93 w - 36.47 = 0$ ($H_0$ in $km sec^{-1} Mpc^{-1}$). This equation is derived by assuming that both $\Omega_{0 \rm m}h^2$ and $d_A=\int_0^{z_{rec}}\frac{dz}{H(z)}$ remain constant (for invariant CMB spectrum) and equal to their best fit Planck/$\Lambda$ CDM values as $H_0$, $\Omega_{0 \rm m}$ and $w$ vary. For $w=-1$, this linear degeneracy equation leads to the best fit $H_0=67.4 km sec^{-1} Mpc^{-1}$ as expected. For $w=-1.22$ the corresponding predicted CMB best fit Hubble constant is $H_0=74 km sec^{-1} Mpc^{-1}$ which is identical with the value obtained by local distance ladder measurements while the best fit matter density parameter is predicted to decrease since $\Omega_{0 \rm m}h^2$ is fixed. We verify the above $H_0-w$ degeneracy equation by fitting a $w$CDM model with fixed values of $w$ to the Planck TT spectrum showing also that the quality of fit ($\chi^2$) is similar to that of $\Lambda$ CDM. However, when including SnIa, BAO or growth data the quality of fit becomes worse than \lcdm when $w< -1$. Finally, we generalize the $H_0-w(z)$ degeneracy equation for the parametrization $w(z)=w_0+w_1 z/(1+z)$ and identify analytically the full $w_0-w_1$ parameter region (straight line) that leads to a best fit $H_0=74 km sec^{-1} Mpc^{-1}$ in the context of the Planck CMB spectrum. This exploitation of $H_0-w(z)$ degeneracy can lead to immediate identification of all parameter values of a given $w(z)$ parametrization that can potentially resolve the $H_0$ tension.

Citing the paper

If you use any of the above codes or the figures in a published work please cite the following paper:
H0 Tension, Phantom Dark Energy and Cosmological Parameter Degeneracies
George Alestas, Lavrentios Kazantzidis and Leandros Perivolaropoulos, arxiv:2004.08363

Any further questions/comments are welcome.

Authors List

George Alestas - [email protected]
Lavrentios Kazantzidis - [email protected]
Leandros Perivolaropoulos - [email protected]

h0_tension_data's People

Contributors

georgealestas avatar

Watchers

 avatar  avatar

Recommend Projects

  • React photo React

    A declarative, efficient, and flexible JavaScript library for building user interfaces.

  • Vue.js photo Vue.js

    ๐Ÿ–– Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.

  • Typescript photo Typescript

    TypeScript is a superset of JavaScript that compiles to clean JavaScript output.

  • TensorFlow photo TensorFlow

    An Open Source Machine Learning Framework for Everyone

  • Django photo Django

    The Web framework for perfectionists with deadlines.

  • D3 photo D3

    Bring data to life with SVG, Canvas and HTML. ๐Ÿ“Š๐Ÿ“ˆ๐ŸŽ‰

Recommend Topics

  • javascript

    JavaScript (JS) is a lightweight interpreted programming language with first-class functions.

  • web

    Some thing interesting about web. New door for the world.

  • server

    A server is a program made to process requests and deliver data to clients.

  • Machine learning

    Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.

  • Game

    Some thing interesting about game, make everyone happy.

Recommend Org

  • Facebook photo Facebook

    We are working to build community through open source technology. NB: members must have two-factor auth.

  • Microsoft photo Microsoft

    Open source projects and samples from Microsoft.

  • Google photo Google

    Google โค๏ธ Open Source for everyone.

  • D3 photo D3

    Data-Driven Documents codes.