Week 8 - Quasars & Future work


Well, i'm back in chennai again, back at IIT Madras and back to, let's say, a *normal* college life. But I'm still interested in following what i started last summer.

As you can see from my report here, and the blog posts from my previous weeks - I've mostly reproduced results from the first paper on my list - Richards et al. (2001). The next papers on the list are on Photometric Redshifts of Quasars by Richards et al (2001), Composite Quasar Spectrum from the SDSS by Vanden Berk et al (2001) and Simulated colors of objects in the SDSS color space by Fan et al (1999). 

All three of these papers feed off one another and complement each other! 

A composite quasar spectrum i used to simulate the colors of a quasar at various redshifts - inorder to do this we need the band structures of the 5 bands - u, g, r, i, z of the SDSS. These can be obtained here. The loop side though is that this data is from 2001 and i haven't been able to find a more recent data pertaining to the band structures. A more recent data set is necessary as it is widely known that the filter response changes over time - if not over a couple of years, i'm sure it has in the last 12 years! 

u, g, r, i, z filter Structure

Coming to the composite quasar spectrum used to simulate the SDSS color space, this was made - again in the 2001. A more recent quasar composite by the SDSS team isn't available. The original one can be found here but again, the necessity of a more recent quasar composite - one that encompasses the whole SDSS observable range of 3500-9200 A - is because of the large number of quasars found after the commissioning of the SDSS. There are newer composites available but not ones with a broad wavelength range! 

composite quasar spectrum overlapped with the sdss band structure

Coming to the first paper in the list - Photometric redshifts of quasars by Richards et al (2001) - this should make for an interesting weekend's work albeit computationally intensive - extremely intensive! 

Well there you go, for the last week I've been going over my report - making finer corrections, looking for ways to extend the summer project and planning out the semester that follows. 
Let's see how much of it bears fruit! 

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