INITIATIVE FOR COSMOLOGY

Welcome!

This site is designed to make cosmology calculations easy and pain-free. Here, you will find a host of tools and resources for performing calculations, ranging from distance calculations to cosmological error predictions for future surveys.

The site also contains a set of tutorials and links that are useful whether you are a newbie to cosmology or a seasoned professional. These resources have been made available in an easy-to-access format and will be continually updated and expanded.

COSMOLOGY TOOLS:

You can perform a calculation either by using your web browser or by downloading the source code. To get started you can either go to tools, and you will be guided through each step. Alternatively, you can use the QuickStart Calculator to the right.

Here is a set of tools that will allow you to easily perform a wide range of cosmological calculations. In terms of user interface, you have the option of using our interactive web tools or downloading the source code directly.

USING YOUR WEB BROWSER:

Using this interactive tool you will be able to calculate most cosmological functions, including distant measurements, growth factor, powerspectra and parameter errors estimated for cosmology experiments. Currently, this tool can perform calculations for weak lensing (WL), baryon acoustic oscillations (BAO) and supernovae (SNe). This web-based interactive tool is powered by the package iCosmo.

DOWNLOADING THE SOURCE CODE:

iCosmo is a general purpose cosmology calculation suite written in IDL. The source code, along with general documentations and user guides, can be found here. The packages are modular. New features, such as additional cosmological probes, are easy to add. Look at this simple tutorial [link here] for how to do this.

COSMOLOGY RESOURCES:

Here you will find general cosmology support materials, such as tutorials and links to external sites. To find the material you need go to resources or use the QuickStart Tutorial to the right. If you wish to create your own interactive web pages you can use the templates available here. A discussion forum for the tools and resources is provided at Cosmocoffee.

For those interested in learning more about cosmology we have set up a set of wikis and web pages to help. These will link to both teaching resources as well as links to other publicly available source code that are widely used in astronomy. All of these have been set up to be useful for both newbies as well as seasoned professionals.

GRAVITATIONAL LENSING WIKI:

This wiki is a centralised resource for a wide range of gravitational lensing probes, including strong lensing, weak lensing, cosmic shear and micro lensing. Newbies, such as fresh graduate students, should be able to navigate these pages and find everything they need become a lensing professional.

GALAXY CORRELATIONS WIKI:

This wiki contains information about galaxy clustering, including background material on Baryon Acoustic Oscillations (BAO).

CMB CORRELATIONS WIKI:

This wiki contains information about Cosmic Microwave Background (CMB) anisotropy correlations.

For the purposes of this site we shall be using the following definitions for different lensing regimes:

Strong Lensing: Strong lensing is when the effects of gravitational lensing are so high that a single source produces multiple images. This usually occurs if the light from a distant object passes very close to the centre of a galaxy or cluster. In this scenario the positions, magnifications and time delay of the images is used to study the lens, source of background cosmology.

Weak Lensing: Weak lensing occurs when the gravitational lensing effect is not strong enough to cause multiple images. Instead the image of a distant object is distorted by foreground objects. By measuring the distortion pattern of background objects, we are able to measure and reconstruct the mass of foreground objects.

Cosmic Lensing: Even if we look at patches of sky that is fairly ‘empty’ the light from distant objects will be perturbed by the general matter distribution of the Universe. In this regime lensing is studied using statistical techniques, such as the two point correlation function of the shape distortions. These statistics are used to measure general properties of the Universe such as the amount and type of dark matter and dark energy.

Micro Lensing: Micro lensing is typically used to the lensing of point like objects, for instance stars are small and distant that they behave like a point source. Here we track the brightness of these objects since the lensing by an object that moves between us and the background star (this is typically another star, a black hole or a lump of dark matter) causes the temporary brightening of the background star. One application of micro lensing is the search or Earth-like extra solar planets.

It is designed for both newbies who would like to learn more about galaxy correlations as well as professionals who wish to share resources. This site focusses on the following cosmological probes:

Galaxy Auto-Correlations: The galaxies are not evenly distributed in the sky and measuring fluctuations in the galaxy field is useful tool for understanding cosmology. These include intrinsic fluctuations in the galaxy distribution, which result from primordial fluctuations in the dark matter density field, and their evolution. These include many features and can be measured using different observables - depending on which observable is used, the correlation is often referred to as 'galaxy power spectrum' or 'galaxy correlation function'.

Cosmic Magnification: is also referred to as magnification bias. It is a lensing effect which can make galaxy populations at different redshifts appear correlated, even though they are intrinsically uncorrelated.

Correlations between the Cosmic Microwave Background (CMB) and the galaxy density field. It is a companion Website to that dedicated to gravitational lensing and galaxy correlations. It is designed for both newbies who would like to learn more about different CMB correlations as well as professionals who wish to share resources. This site focusses on the following different correlations:


EXTERNAL LINKS:

A wide range of useful cosmology resources already exist on the web. Here’s we highlight some of these.

NEWS:

12/07/2020 - iCosmo Version 1.2. Download version 1.2 of the iCosmo source code from here.
15/05/2020 - Path Integral Marginalization. Module for astro-ph/1005.2063 to be included in iCosmo v2.0.
21/03/2020 - Marginalization. Module for astro-ph/1003.1136 to be included in iCosmo v2.0.
02/09/2019 - Halo Model. Module for astro-ph/0909.0529 to be included in iCosmo v2.0.
21/05/2019 - w(z) eigenfunctions. Module for astro-ph/0905.3383 to be included in iCosmo v2.0.
20/05/2019 - Hardware-Software balance. Code for astro-ph/0905.3176 can be downloaded here iCosmo PublicAstroCodes.
11/02/2019 - Redshift Distortion & ISW. Module for astro-ph/0902.1759 to be included in iCosmo v2.0.
21/01/2019 - Cloud Cosmology. Article available here. Template web pages available here.
11/12/2018 - Form Filling Functions. Module for astro-ph/0812.1966 to be included in iCosmo v2.0. Module available now here.
11/10/2018 - iCosmo Presented at Dark Energy Conference Munich. Download the talk here.
09/10/2018 - iCosmo V1.1 released.
09/10/2018 - iCosmo paper submitted to astro-ph. Available for download here.
29/09/2018 - iCosmo V1.0 released.

iCosmo

CMB priors in iCosmo
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No new posts Comoving Distance
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No new posts SN redshift range in Fisher Calculations
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No new posts Re-ionisation optical depth
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No new posts Number of z bins in lensing power spectrum using iCosmo
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No new posts Interactive Cosmological Tools