New Results from the Atacama Cosmology Telescope!

There’s some excitement in cosmological circles with the announcement of new results from the Atacama Cosmology Telescope, which is situated in the Atacama Desert in Chile. The two papers describing the new results can be found on the arXiv here and here and the data set will be made available here (it is Data Release 4; or DR4 for short).

If you want a laugh, the structure in the above map is on arc-minute scales – exactly the sort of thing I was trying to simulate way back in the 1980s. Here’s an ancient monochrome plot! The contours show 1σ, 2σ and 3σ fluctuations above the mean rather than the full distribution shown in the map above.

The full results will be discussed at a Zoom presentation at 11am Eastern Time (4pm Irish Time). I suspect it will be very busy so you will have to register in advance.

UPDATE: The Webinar is over but was recorded. I will post a link to the video when it is available. You can then guess which question was mine!

The new results from ACTPol are consistent with those from Planck, even down to the colour scheme used for the map, but the line taken by most media presentations I’ve seen (e.g. here and here) has been the issue of the Hubble Constant. The value of around 67.6 km s-1 Mpc-1 obtained by the Atacama Cosmology Telescope, though consistent with Planck measurements, is lower than most distance-scale measurements of H0. The dichotomy between `low’ estimates from cosmological observations and `high’ values persists.

This gives me an excuse to include my poll again:

There have been nearly a thousand responses so far, with opinion very divided.

The burning question however is when will face masks featuring the above map be made available for purchase? It could be a nice little earner…

6 Responses to “New Results from the Atacama Cosmology Telescope!”

  1. I think it’s another fascinating result. Maybe we are looking at this the wrong way around; I’ve always found it amazing that today’s rate of expansion can be estimated from measurements of the CMB. Maybe it’s not that surprising if that extrapolation doesn’t quite work….

    • Phillip Helbig Says:

      It is pretty straightforward if you assume a F(L)RW model. If you don’t then to what extent it is possible depends on your model.

      Of course, if one measures the Hubble constant locally, then one measures it locally. If one measures it via the CMB, then obviously more than just local measurements are involved, but the local value follows from the model. Obviously, there is no way to “directly” measure the local rate via a distant object.

  2. Peter, how about a poll concerning which answer will turn out to be correct? I’m no theorist, but my money is on the direct measurements, simply because there are more assumptions involved in the CMB method (although I know distance scales have been treacherous in the past.)

  3. […] A blog about the Universe, and all that surrounds it « New Results from the Atacama Cosmology Telescope! […]

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