Blog about cosmology

A measurement of the Hubble constant based on quasars suggests possible changes to cosmological models

An article published in the journal “Nature Astronomy” describes the use of quasars as cosmic tracers to measure the expansion of the universe up to 12 billion years ago. Guido Risaliti of the University of Florence and Elisabeta Lusso of Durham University studied the X-ray and optical emissions of a number of quasars using the comparison between those emissions to accurately assess their distances. The results could explain the discrepancies between the different measurements carried out with other methods suggesting that the density of the mysterious dark energy isn’t constant over time.

A verification of dark matter heating

An article published in the journal “Monthly Notices of the Royal Astronomical Society” reports confirmations to the hypothesis of the effect known as dark matter heating. A team of researchers looked for the effects of the presence of dark matter in dwarf galaxies relatively close to the Milky Way, finding the confirmation that star formation can heat it causing it to move outwards. It’s a new possibility to study dark matter to try to understand its nature.

Artist's concept of the universe on a 5D bubble (Image courtesy Suvendu Giri)

An article published in the journal “Physical Review Letters” describes a new model of the universe that proposes that it exists on the edge of an expanding bubble in a five-dimension space-time. A team of researchers from the Swedish University of Uppsala used string theory to hypothesize that the matter existing in the universe is accomodated at the edges of strings that extend into the fifth dimension. According to this hypothesis, what is called dark energy is an effect described by a cosmological constant in the four-dimension Friedmann equations.

The Abell S1063 galaxy cluster (Image NASA, ESA, and M. Montes (University of New South Wales, Sydney, Australia))

An article published in the journal “Monthly Notices of the Royal Astronomical Society” describes a new method to detect and map the dark matter existing in galaxy clusters with a higher precision than those used so far. Mireia Montes of the University of New South Wales, Australia, and Ignacio Trujillo of the Canary Islands Institute of Astronomy, Spain, exploited the so-called intracluster light, the faint light within galaxy clusters produced by their interaction, detected in the Hubble Frontier Fields program, to map the distribution of dark matter within them.

Some ASKAP antennas with the Milky Way overhead (Image courtesy Alex Cherney/CSIRO. All rights reserved)

An article published in the journal “Nature” reports the results of a survey on Fast Radio Bursts (FRBs), intense radio emissions from other galaxies. A team of researchers used the Australia Square Kilometer Array Pathfinder (ASKAP) radio telescope to search for Fast Radio Bursts discovering 20 in a year, almost doubling the number previously detected. Their analysis suggests that their characteristics evolve over time.