Astronomy and Coffee

Late post again ... yes, again ...

Late from yesterday after a couple of days without posting. Friday I was back from Bonn but the time was used to try to put forward a couple of personal issues, which also took monday and part of tuesday and will take some time the next few day (hopefully it ends soon).

The day was partially used to choose a target to the one single night we got at the INT (despite having asked for 8 nights). The complication is that the dates were chosen because we could observe 2 "half groups" each night. Explaining: in the first half of the night we'd observe "group 1" setting in one filter, and the second half of the night we'd observed "group 2" rising. The next night the same procedure in a second filter. Then the following nights we'd observed groups 3 and 4, 5 and 6, and 7 and 8. With one single night, we have to find an object that can be observed the whole night. But none of the objects of interest are fully in the sky this time of the year ... a couple of "less damage" candidates appeared, now we're discussing that.

At night I read the thesis of my friend Thorsten Tepper-Garcia, who will present July, 11th. The thesis is very good, I liked it. Haven't got to the mathematical details, but there should be no problem with it. The work was on MC simulations of HI clouds and it's influence on the observed magnitudes, cosmic flux decrement and photometry redshifts.

Also worth commenting the two papers of Krick et al about intracluster diffuse light in 10 clusters at two redshift regions (0.05-0.1 and 0.15-0.3). A very nice work, exausting, where most of the problems on this kind of analysis was taken care carefully. The colors are compatible with old stellar population. Correlations between ICL flux and M3-M1, density and total galaxy flux were found, but no correlation between ICL flux and redshift maybe due to selection
effects. The correlation between M3-M1 shows us that clusters with cD galaxies have less ICL than clusters with no cD. It seems logical for me since ICL and cD halo are hard to be differenciated, if there's any difference, if the cD is not just the "laying" in the potencial, as the ICL. The ICL fraction has an anticorrelation with mass, with large error bars, oposed to the results of simulations and a week anticorrelation with redshift, an expected correlation. No correlation between color gradients and other cluster properties and the ICL profiles are fitted by a de Vaucouleurs or an exponential profiles and most of them can also be fitted by a Hubble-Reynolds profile ("a substitute for the complicated surface brightness profile of an NFW density profile").

posted by Cris Da Rocha @ 11:59 PM