In the case of the Cold Spot, this hypothesis already has support from surveys of galaxies, but the DES data, that IAC researcher Aurelio Carnero Rosell also helped to construct, provides a key new observable.
Thus, by studying this effect in detail, cosmologists can infer the properties of dark energy. This net loss of energy is equivalent to a slight chill in the temperatures of CMB photons traversing supervoids. Therefore, at the exit of a supervoid, the CMB photons, instead of recovering the same energy invested in going up the hill, lose part of it as the dark energy softens the descent. Dark energy acts as a repulsive force, the opposite of gravity, so that it slows down the rate of formation of the largest cosmic structures and smooths them out. However, during their passage, these photons suffer from the effect of dark energy, which is responsible for cosmic expansion. On entry, they must invest energy to traverse an under-density. Credit: Gergö Kránicz and András KovácsĮnergetically, a supervoid is best imagined as a hill to climb from the perspective of the CMB photons in their journey towards our telescopes. In particular, cosmologists can use this giant notch as a unique laboratory to learn about the elusive dark energy. The DES team was led by the hypothesis that a supervoid might, at least in part, explain why this spot is significantly larger and colder than expected. However, a cold region as large as the "cold spot" seems very unlikely according to the standard cosmological model. This anomaly corresponds to a structure, found over the southern ecliptic hemisphere sky, with a cooler-than-average temperature. This region is also the location of the so-called Cold Spot which is one of the large-scale anomalies of the Cosmic Microwave Background (CMB), a type of fossil radiation from the origins of the Universe. New research by the Dark Energy Survey (DES) collaboration and led by the Instituto de Astrofísica de Canarias (IAC) researcher András Kovács has confirmed that a large under-density of matter, a supervoid, lurks nearby in the Eridanus constellation. However, less is known about our cosmic neighbourhood.
After the meticulous charting of our cosmic backyard, recent discoveries have placed our galaxy into the supercluster Laniakea as part of the cosmic web of galaxies. The possibility of mapping the largest structures in the Universe has always been an aspiration of astrophysics. The result is published today in Monthly Notices of the Royal Astronomical Society. Its study could provide new clues to understanding the nature of dark energy. Research by the Dark Energy Survey (DES) collaboration, in which the Instituto de Astrofísica de Canarias (IAC) participates, has confirmed the presence of a supervoid, an extremely large region with a lower-than-average density of matter, in the constellation Eridanus.