I am studying the trouble with the measurements of the Hubble constant. I have already studied the measurements using the Standard Candles and the time delay due to the gravitational lensing.

I found nothing about the measurement of the Hubble constant obtained by the Planck collaboration, only the values obtained. Could you explain me how did they obtain the value of $H_0$? Could you give a me a good review?

  • $\begingroup$ The Planck Collaborators have published somewhere around 50 papers about the mission and the explanation is definitely in one of those (I just forget which one). $\endgroup$ – Kyle Kanos Sep 2 '17 at 16:06
  • $\begingroup$ May I ask what the objective of your study is? As I understand, the PLANCK calculations accounted for the "dark energy" and produced lower values than the later measurements. Since the dark energy is hypothetical and has not been observed, its use in calculating an experimental parameter is controversial to say the list. Also, while the Hubble parameter is constant in space, it obviously changes in time in the reverse proportion to time since the Big Bang. $\endgroup$ – safesphere Sep 2 '17 at 16:08
  • $\begingroup$ @KyleKanos I tried to read some of these papers...but they are simply to many and to much long. I hoped that there was something in this one arxiv.org/abs/1502.01589...but I found nothing. $\endgroup$ – Saramago Sep 2 '17 at 16:10
  • $\begingroup$ Also, I think this question was asked previously, shortly after the results were released. I'd dig it up and link it, but the mobile search is not so effective at that. $\endgroup$ – Kyle Kanos Sep 2 '17 at 16:11
  • $\begingroup$ @safesphere I want to study the different techniques used to obtain the value of $H_0$. I like a lot the SN 1a technique because it seems to be really general and model indipendent. However, I also want to study the other techniques. $\endgroup$ – Saramago Sep 2 '17 at 16:15

From the Planck publications, it is seen that the Hubble constant comes from a fit to the CMB data in a specific model described here :

Within the minimal, six-parameter model the expansion rate is well determined, independent of the distance ladder. One of the most striking results of the nominal mission is that the best- fit Hubble constant H_0= (67+/-1.2)km sec^-1Mpc^-1 , is lower than that measured using traditional techniques, though in agreement with that determined by other CMB experiments

It is referred in the newer publication here .

The Planck 2013 analysis showed that the temperature power spectrum from Planck was remarkably consistent with a spatially flat ΛCDM cosmology specified by six parameters, which we will refer to as the base ΛCDM model.

The disagreements with other methods are discussed in section 5.4

So a specific cosmological model is used to fit the data.


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