Interactive figures in the browser - CMB Power Spectra


August 30, 2013

For a long time I’ve been curious about trying out d3.js , the javascript plotting library which is becoming the standard for interactive plotting in the browser.

What is really appealing is the capability of sharing with other people powerful interactive visualization simply via the link to a web page. This will hopefully be the future of scientific publications, as envisioned, for example, by Authorea .

An interesting example related to my work on Planck is a plot of the high number of Angular Power Spectra of the anisotropies of the Cosmic Microwave Background Temperature.

The CMB Power spectra describe how the temperature fluctuations were distributed in the sky as a function of the angular scale, for example the largest peak at about 1 degree means that the brightest cold/warm spots of the CMB have that angular size, see The Universe Simulator in the browser .

The Planck Collaboration released a combined spectrum, which aggregates several channels to give the best result, spectra frequency by frequency (for some frequencies split in detector-sets) and a best-fit spectrum given a Universe Model.

It is also interesting to compare to the latest release spectrum by WMAP with 9 years of data.

The plan is to create a visualization where it is easier to zoom to different angular scales on the horizontal axis and quickly show/hide each curve.

For this I used rickshaw , a library based on d3.js which makes it easier to create time-series plots.

In fact most of the features are already implemented, it is just a matter of configuring them, see the code on github:

The most complex task is actually to load all the data, previously converted to JSON, in the background from the server and push them in a data structure which is understood by rickshaw.

Check out the result: