Theoretical Data UCD Proposal

[Marco Molinaro]

Dear all,
we want to start writing down a list of quantities for theoretical data 
and then propose these quantities for inclusion into the UCD1+ 
controlled vocabulary.
The ITVO group works on cosmological simulations and stellar evolution 
models. As a first step these notes notes are dealing with cosmological 
quantities.
The underlying idea is to contribute to the

http://www.ivoa.net/twiki/bin/view/IVOA/IVOATheoryGeneralRequirements

discussion and, at the same time, suggest some ucds for simulated data. 
We opened a wiki page where everyone can add missing quantities and 
related ucds

http://www.ivoa.net/twiki/bin/view/IVOA/TheoreticalDataUCDProposal

We feel the absence of the cosmological parameters' ucds, like:

H, H0 - Hubble parameter, constant
all the 'omega' parameters (matter, baryon, lambda, ...)
sigma8, spectrum-normalization parameter.
...

For all of these we are, at present, using the not-so-descriptive 
src.morph.param;phys.cosmology ucd compound and this is a problem 
because cosmological simulations make large use of these parameters for 
their description.
Maybe another important parameter to add is the expansion factor which 
pairs the cosmological redshift (for this last the ucd already exists).

Other ucds we want to add (or ask attention for) are related to the 
'temperatures' used, for example in galaxy clusters simulations. we 
think a good idea is to add ucds like

phys.temperature.emissionweighted
phys.temperature.massweighted
phys.temperature.speclike

following the idea of the existing .effective and .electron ones.
Another ucd, or ucd group, could be related with the 'critical density' 
radius, adding the simple phys.radius.rhocritic and/or its extensions to 
phys.radius.rhocritic.NNN (namely NNN=200, 500, 2500).
Maybe another choice for this problem could be something like
phys.size.radius;phys.cosmology.rhocritic
which is better if one wants to relate the critical density to other 
quantities than the radius (let's say: 
phys.temperature.speclike;phys.cosmology.rhocritic)

To simplify all these ucds an idea could be adding a new category, to 
the already existing 12, named 'cosm' to replace the phys.cosmology 
which is an 'S' word. But I don't know if the resulting semplification 
in the single ucds is a sufficient gain compared to adding a categorie 
in the UCD schema.

We also want to add other ucds like:
- 'object.gas', 'object.stellar', 'object.darkmatter', ...and so on, as 
'S' words to specify which masses, temperatures or other quantities we 
are talking of
- a ucd for the cosmological model of the simulation
- a ucd for the code used in the simulation
- a ucd for the linear size of the simulated cosmological box

Together with these proposed ucds we want to focus the attention of the 
community on the ucds needed by the stellar simulations.

Regards
	Marco

Marco Molinaro
INAF - Trieste Astronomical Observatory
Phone.: +39 040 3199 152
e-mail: molinaro at oats.inaf.it
web site: http://wwwas.oat.ts.astro.it/