Dark matter

The galaxy NGC1052-DF2 (Image NASA, ESA, Z. Shen and P. van Dokkum (Yale University), and S. Danieli (Institute for Advanced Study))

An article published in “The Astrophysical Journal Letters” reports a precise measurement of the distance of the galaxy NGC1052-DF2 that was used to confirm that it’s almost devoid of dark matter, a notable anomaly. A team of researchers led by Pieter van Dokkum of Yale University used the Hubble Space Telescope to observe the red giants on the outskirts of NGC1052-DF2 using them as “standard candles” taking advantage of the fact that they all reach the same peak in brightness. Understanding why so few of the gravitational effects attributed to dark matter are detected in this galaxy may offer new clues to its nature.

Deep field image (Image Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA Acknowledgments: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) & D. de Martin (NSF’s NOIRLab))

29 articles report various aspects of the results of a major cosmological research on the largest sample of galaxies – 226 million of them – ever observed to produce the most accurate measurements of the composition and growth of the universe. More than 400 scientists from the DES (Dark Energy Survey) Collaboration used images captured by the Dark Energy Camera in the first three years of the program, which started in 2013, to obtain results. The goal is to improve our knowledge of the universe, in particular, the nature of dark matter and dark energy.

Artist's concept of a supermassive black hole surrounded by galaxies within a cosmic web (Image ESO/L. Calçada)

An article published in the journal “Astronomy & Astrophysics Letters” reports a study on a group of six galaxies surrounding a supermassive black hole which date back to an early epoch when the universe was less than a billion years old. A team of researchers led by Marco Mignoli of the Italian National Institute of Astrophysics (INAF), Bologna, used ESO’s Very Large Telescope (VLT) and the Large Binocular Telescope (LBT) to observe that structure which turned out to be complex as it includes filaments of matter that extend for a distance over 300 times the size of the Milky Way. The gas that concentrates in that structure forms what have been likened to the threads of a spider’s web, and that gas could be responsible for the development of a supermassive black hole in such a remote time.

39 ancestors of massive elliptical galaxies discovered in the early universe

An article published in the journal “Nature” reports the discovery of 39 galaxies in the early universe. A team of researchers combined data from different telescopes to identify a group of galaxies dating back to the first two billion years after the Big Bang that were invisible to previous observations in their areas conducted at optical frequencies. Their study could offer new information on the evolution of galaxies, on the supermassive black holes at their center and also on the distribution of dark matter.

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.