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sebastian-schindler / PhD

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Add interesting sources to high-dimensional visualizations #1

Open sebastian-schindler opened 1 month ago

sebastian-schindler commented 1 month ago

Indicate interesting sources in high-dimensional visualization plots like corner plot or UMAP plot. It is already interesting to see where in the phase space they lie (maybe they are all clumped up together, or far away from the rest in a small cluster).

Definitely interesting: NGC 1068. Would expect it to be outside the main cluster, because it is very close by and thus absolutely brighter.

Interesting sources identified previously:

The NGC sources are Seyferts from the Neronov, Savchenko, Semikoz paper.

sebastian-schindler commented 1 month ago

The IDs in SOIs.pkl file written previously are 1RXS identifiers, but current catalog has only 2RXS identifiers (or AllWISE or others). So some identifier of these sources included in the current catalog need to be figured out.

sebastian-schindler commented 1 month ago

The available identifiers are for the...

Therefore, the AllWISE identifier would be the best option, also because most objects will have a detection by WISE.

sebastian-schindler commented 1 month ago

In Sarah's final catalog the AllWISE identifiers are formatted in a strange way. For example, the following ID is displayed in the notebook as follows:

The first b and set of quotation marks is expected, as the data is saved as byte sequences, which are like this marked in python. Therefore, the following would have been expected to be displayed:

However, the inner set of quotation marks including the b are part of the string itself and thus superfluous, as is the trailing whitespace. The values can be corrected by this:

lambda x: x[2:-1].strip()

The values remain as a byte sequence.

sebastian-schindler commented 1 month ago

With the above described preparations, the interesting sources can be searched in the catalog. It turns out that neither in the final nor the intermediate catalog any of the sources are contained. Is this expected or plausible?

One of the constraints of the catalog is detection of a source in x-rays. Is it plausible that none of the interesting sources are x-ray bright (enough)?

sebastian-schindler commented 1 month ago

All interesting sources do have an x-ray detection in 2RXS, as checked by querying SIMBAD/VizieR. Thus, the requirement of an x-ray detection is no reason that these sources are excluded from the catalog.

sebastian-schindler commented 1 month ago

After checking the cuts applied in Sarah's catalog, the following was identified as the cause that removes all interesting sources: image

This plot shows the position of the interesting sources in the same plane: image

The cut line removes the entire lower population, which contains all interesting sources.

What is puzzling, is that all interesting sources are Seyfert galaxies, which are AGN; but the cuts that remove them are supposedly designed to select AGN. It appears that these cuts are too strict, because they remove a lot of interesting AGN.

sebastian-schindler commented 1 month ago

The cut was developed by Salvato et al. based on another survey at lower x-ray energies that separates AGN from stars and galaxies, and extended to higher x-ray energies to be applied to 2RXS data. image They mention an efficiency of AGN selection of 99 % and impurities of < 0.1 % regarding stars.