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Showing posts from August, 2013

Quasars - An Overview

I promise, this is the last post on quasars. I'll move on after this one! 
This post is an attempt to consolidate my summer work and explain it in easier terms - better than how my posts have been so far. So, any comments on the writing style or any questions are welcome. 
so, moving on... 

What are Quasars?! 

Quasars are super massive black holes at the center of galaxies. These black holes are what are called active black holes - they feed on the surrounding gas and dust in the galaxy and emit radiation! You might then ask "Don't all galaxies have black holes at their center?". Damn right, they do. But these are inactive galaxies - because there isn't any (more) free gas lying around for the black hole to feed on. You see, over the course of evolution of a galaxy, gas starts to condense to form stars. So, a very young galaxy with a super massive black hole is what we are calling a Quasar. Quasars are categorized under AGN - Active Galactic Nuclei. The other types …

Animation using GNUPlot

Animation using GNUPlotI've been trying to create an animation depicting a quasar spectrum moving across the 5 SDSS pass bands with respect to redshift. It is important to visualise what emission lines are moving in and out of bands to be able to understand the color-redshift plots and the changes in it.
I've tried doing this using the animate function in matplotlib, python but i wasn't able to make it work - meaning i worked on it for a couple of days and then i gave up, not having found solutions for my problems on the internet.
And then i came across this site, where the gunn-peterson trough and the lyman alpha forest have been depicted - in a beautiful manner. And this got me interested in using js and d3 to do the animations and make it dynamic - using sliders etc.
In the meanwhile, i thought i'd look up and see if there was a way to create animations in gnuplot and whoopdedoo, what do i find but nirvana!

In the image, you see 5 static curves and one dynam…