Week 5: Final lab session

Luminosity bins 

We suspected that there is a bias when looking at high redshift sources, much like there is a 3-sigma detection limit that limits the sources we see at high redshift, we predict that more distant sources must be more luminous for them to be detected by us. To eliminate this bias, we bin by luminosity.  
We have a total of 5 bins of Lyman alpha luminosity ranging from 10^42.1 ergs^-1 to 10^44.6 ergs^-1 in intervals of 10^0.5 ergs^-1. Lyman alpha luminosity was used instead of X-ray or radio since all AGN are Lyman alpha emitters and this luminosity has not been used to calculate accretion rates. 

Figure 1: Redshift vs BHAR. All AGN sources are plotted and have been placed into bins of Lyman alpha luminosity. The lowest accretion rates trail upward at higher redshift due to the 3-sigma detection limit. 

If what we thought was correct, we would have expected the most luminous sources to be at high redshift. Figure 1 shows that this is not the case; our most luminous sources are represented by red points which are found between z ~ 2.5 and z ~ 3.5. In fact, our most distant sources are the second least luminous sources suggesting that there is no bias based on luminosity of the sources. 

Most AGN sources are found around redshift 3 which agrees with the theory that AGN activity peaks between redshift 1 and 3. 

Figure 2: Lyman alpha vs BHAR. 

We plotted Figure 2 to see whether there was any correlation between how luminous sources were in the Lyman alpha band and their BHAR. We find that there is a small, positive correlation for all the AGN sources. 

Looking within the bins we different trends at different luminosities. What we found interesting is that at high luminosities (>10^43.1ergs^-1), all the classifiable sources are Type 1: Compact. This could suggest something about the structure of galaxies and how this relates to its luminosity, or it could be coincidence. Out of all the AGN, 232 are classifiable sources (morphology type 0 – 3), 63% of these sources are Type 1: Compact and the top two most luminous bins of Lyman alpha luminosity contain only 19% of the classifiable AGN. There is a good chance then that these results are just coincidental. 

Comparing the data

After all our hard work, we thought it was important to check that we had reproduced the data correctly. 

Figure 3: Data obtained from the reference paper against data calculated by CHARSS. The points lie on an x = y line showing that our calculated values are in complete agreement with the expected ones. 

In the coming weeks we will be writing the report ready to publish our results. 

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