User talk:SkyFlubbler/Archives/2022/June

Phoenix A

Where did you find the name "Phoenix A" for the central galaxy in the Phoenix Cluster. I can't seem to find it anyway on Simbad and what makes it better than the previous mass? Faren29 (talk) 16:42, 16 June 2022 (UTC)

The name is used in the NASA/IPAC Extragalactic Database (see here where I actually used the 2MASS coordinate to remove any biases). This is one instance where they have associated the radio source naming scheme to refer to the main galaxy itself.

Regarding the new mass, this is because of a very simple line used by the authors of the reference to the older mass (see here) on page 24:

"We stress that both the accretion rate and the black hole mass are highly uncertain, due to the order of magnitude uncertainty in the bolometric correction and black hole mass."

The methodology that the previous reference also used was by using spheroidal luminosity. As stated by Dullo 2015 (the source for the mass of MS 0735.6+7421), there is a problem when using spheroidal luminosity in BCGs of galaxy clusters, due to their unusual dynamics and behavior. You can only use spheroidal luminosity in scale-free elliptical galaxies, not on packed cores. Hence why it is more or less highly uncertain.

The new one was not significantly better, though it is better because it is based on an evolutionary model, along with using core-Sersic curve to make a standard scale (they refer to it as a calorimetric tool) to estimate the black hole's mass. This works better if you have a BCG with unusual characteristics (extended gas outflow, cooling cores) like the one in Phoenix. This is so far the only other source we have. In the future, we might be able to obtain a mass using a more robust method.

This number (100 billion M_☉) may seem so impossibly large, but same goes for Ton 618. The spectral line used as the basis for its mass estimate is from 1978, which makes it even worse than Phoenix if reliability is just the issue here. It should be noted that in the reference for Phoenix, it is the only instance where it has been explicitly mentioned in the abstract, unlike the others, which gives me a feeling of confidence on the side of the author.

If it suits you, we can discuss this even further in the talk page of the list. SkyFlubbler (talk) 18:22, 16 June 2022 (UTC)

I think it's suitable enough and does not warrant a discussion, considering there is no popular or commonly-used name for the BCG of the Phoenix Cluster. Faren29 (talk) 18:35, 16 June 2022 (UTC)