Much ado about (almost) nothing ?

[diogenesNY]

Astronomers discover largest known structure in the universe is ... a big hole.

Scientists searching for an explanation for an unusually cool area of sky instead discovered a supervoid: an empty spherical blob 1.8 billion light years across

Hannah Devlin, science correspondent. UK Guardian
@hannahdev Monday 20 April 2015 12.22 EDT

Astronomers have discovered what they say is the largest known structure in the universe: an incredibly big hole.

The “supervoid”, as it is known, is a spherical blob 1.8 billion light years across that is distinguished by its unusual emptiness.


István Szapudi, who led the work at the University of Hawaii at Manoa, described the object as possibly “the largest individual structure ever identified by humanity”.

Its existence only emerged thanks to a targeted astronomical survey, which confirmed that around 10,000 galaxies were “missing” from the part of the sky it sits in.

[article continues]...

http://www.theguardian.com/science/...ure-in-the-universe-is-a-big-hole?CMP=ema_565

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diogenesNY

 

[wabbit]

http://arxiv.org/abs/1405.1566
Detection of a Supervoid Aligned with the Cold Spot of the Cosmic Microwave Background
István Szapudi et al.

We use the WISE-2MASS infrared galaxy catalog matched with Pan-STARRS1 (PS1) galaxies to search for a supervoid in the direction of the Cosmic Microwave Background Cold Spot. Our imaging catalog has median redshift z≃0.14, and we obtain photometric redshifts from PS1 optical colours to create a tomographic map of the galaxy distribution. The radial profile centred on the Cold Spot shows a large low density region, extending over 10's of degrees. Motivated by previous Cosmic Microwave Background results, we test for underdensities within two angular radii, 5∘, and 15∘. The counts in photometric redshift bins show significantly low densities at high detection significance, ≳5σ and ≳6σ, respectively, for the two fiducial radii. The line-of-sight position of the deepest region of the void is z≃0.15−0.25. Our data, combined with an earlier measurement by Granett et al. 2010, are consistent with a large Rvoid=(220±50)h−1Mpc supervoid with δm≃−0.14±0.04 centered at z=0.22±0.03. Such a supervoid, constituting at least a ≃3.3σ fluctuation in a Gaussian distribution of the ΛCDM model, is a plausible cause for the Cold Spot.