Cosmology

39 ancestors of massive elliptical galaxies discovered in the early universe

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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.

Representation of the jet of a gamma-ray burst such as GRB 190114C (Image courtesy Kitty Yeung)

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An article published in “The Astrophysical Journal Letters” reports a study on a gamma-ray burst cataloged as GRB 190114C and detected by NASA’s Swift satellite and the MAGIC telescopes at the Canaries. Professor Evgeny Derishev and Professor Tsvi Piran put together the data from these detecions, which are about photons at very different energies, concluding that the radiations detected must have originated in a jet that moved at a speed of about 99.99% of the speed of light. These are so-called ultra-high energy emissions in the Teraelettronvolt (TeV) range and they think that the mechanism of origin is the inverse Compton scattering while emissions of less energetic photons originate from synchrotron radiation.

Using red giants to estimate the speed of the universe expansion

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An article being published in “The Astrophysical Journal” reports a new attempt to calculate the speed of the universe expansion, this time using red giant stars as a reference. A team of researchers coordinated by Carnegie Institution for Science and University of Chicago and led by astronomer Wendy Freedman used observations made with the Hubble space telescope to perform that calculation. The result has a probability peak at 69.8 km/s per megaparsec, between the values ​​calculated using the two methods that provided discrepant values.

Galaxy NGC 3147 (Image ESA/Hubble & NASA, A. Riess et al.)

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An article published in the journal “Monthly Notices of the Royal Astronomical Society: Letters” reports a study on a supermassive black hole surrounded by a disk of materials that revealed unexpected features. A team of researchers led by Stefano Bianchi, of the University of Roma Tre, Italy, used the Hubble Space Telescope to observe the nucleus of the galaxy NGC 3147 discovering a small and soft disk, a reduced version of the large disks typical of active galactic nuclei, a structure that shouldn’t exist. The discovery represents a new opportunity to test some relativistic effects but could force astronomers to review certain models on active galactic nuclei.

Using neutron star mergers to estimate the speed of the universe expansion

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An article published in the journal “Nature Astronomy” reports the use of observations of the neutron stars merger recorded on August 17, 2017 to try to calculate the value of the Hubble constant, which measures the speed of the universe expansion. That event is the most famous of those recorded so far for gravitational waves due to the importance it had for the so-called multimessenger astronomy but it has already proved useful also to offer an additional way to measure the expansion of the universe that is alternative to the two that are providing a discrepancy in their results.