Saturday, January 16, 2016

Doubts about Type Ia supernovae data and the Lambda CDM model

Do they have a global standard for reporting information on supernova data?
I have seen reports of "redshift" and "magnitude" but to measure a redshift, one must first be sure that they have properly identified the colors that have been redshift.  That's fine.
But then I see reports of "magnitude" being listed through locally defined colors... Red, Green, Blue filters that exist on the telescope itself.
Astronomers are very smart, so they surely take into account that if the colors have shifted, then surely whatever they measure as magnitude should shift, too. 
However, looking through the IAUC (International Astronomical Union Circulars) data on supernova, many report different magnitudes based on filters, but when I read papers supporting the lambda Cold Dark Matter universe based on Type I supernova data, they do not get into the nitty gritty of how the actual magnitude of the supernova is calculated.  In fact, if I recall, correctly, these papers often don't report the magnitude at all; but rather simply report the redshift and distances to the supernova. (And they tend to ignore right-ascension and declination)
To assign the supernova a "distance" is a physical interpretation of the observational characteristics... The observational characteristics are just the Right ascension, Declination, and the spectral analysis. 
Do amateur astronomers sending in International Astronomical Union Circulars have sufficient equipment and training to provide an accurate measurement of magnitude, and be sure they are all measuring and communicating the same quantity?
Or does the information about magnitude through two or three filters give all that is needed to reconstruct the spectral analysis?
Also, when they make a measure of redshift, how confident are they that they have found, for instance, the hydrogen alpha line?  Many IAUC cirucluars report precisely what line they are using to find the redshift, but many just say z=2.1 or whatever, without giving any indication of how it was calculated.

No comments:

Post a Comment