Institute for Astronomy | University of Hawaii | 2015 Apr 20
Astronomers discover what might be the largest known structure in the universe that leaves its imprint on cosmic microwave background radiation. A very large cold spot that has been a mystery for over a decade can now be explained.
In 2004, astronomers examining a map of the radiation leftover from the Big Bang (the cosmic microwave background, or CMB) discovered the Cold Spot, a larger-than-expected unusually cold area of the sky. The physics surrounding the Big Bang theory predicts warmer and cooler spots of various sizes in the infant universe, but a spot this large and this cold was unexpected.
- [i]The Cold Spot area resides in the constellation Eridanus in the southern galactic hemisphere. The insets show the environment of this anomalous patch of the sky as mapped by Szapudi’s team using PS1 and WISE data and as observed in the cosmic microwave background temperature data taken by the Planck satellite. The angular diameter of the vast supervoid aligned with the Cold Spot, which exceeds 30 degrees, is marked by the white circles. [b](Graphics by Gergő Kránicz. Image credit: ESA Planck Collaboration.)[/b][/i]
Now, a team of astronomers led by Dr. István Szapudi of the Institute for Astronomy at the University of Hawaii at Manoa may have found an explanation for the existence of the Cold Spot, which Szapudi says may be “the largest individual structure ever identified by humanity.”
If the Cold Spot originated from the Big Bang itself, it could be a rare sign of exotic physics that the standard cosmology (basically, the Big Bang theory and related physics) does not explain. If, however, it is caused by a foreground structure between us and the CMB, it would be a sign that there is an extremely rare large-scale structure in the mass distribution of the universe.
Using data from Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA’s Wide Field Survey Explorer (WISE) satellite, Szapudi’s team discovered a large supervoid, a vast region 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known universe. This void was found by combining observations taken by PS1 at optical wavelengths with observations taken by WISE at infrared wavelengths to estimate the distance to and position of each galaxy in that part of the sky. ...
Detection of a Supervoid Aligned with the Cold Spot of the Cosmic Microwave Background - István Szapudi et al
- Monthly Notices of the RAS 450(1): 288 (2015 June 11) DOI: 10.1093/mnras/stv488
arXiv.org > astro-ph > arXiv:1405.1566 > 07 May 2014 (v1), 05 Mar 2015 (v2)