Galaxies

Image showing the observations of the supernova SN Refsdal. In the uppermost circle there's the possible observation happened in 1998, in the middle circe the 2015 observation and in the lowermost circle the 2014 observation

The Hubble Space Telescope allowed us to observe a supernova just during the explosion. This is due to the fact that its appearance was foretold. For the first time, the use of complex calculations related to the theory of relativity made it possible to capture the supernova nicknamed Refsdal when it exploded. It’s the first time such a feat was achieved by exploiting the gravitational lensing of that galaxy cluster MACS J1149.5 + 2223, which bent the light from that star showing the explosion several times in different areas of the sky.

The galaxy cluster MACSJ0416.1-2403 observed by the Hubble Space Telescope with the galaxy nicknamed Tayna in the inset (Image NASA, ESA, and L. Infante (Pontificia Universidad Catolica de Chile))

An article published in the journal “Astrophysical Journal” describes the discovery of the faintest galaxy in the early universe. According to this study, this galaxy was born when the universe was “only” about 400 million years old and for this reason was nicknamed Tayna, which means “first born” in the Aymara language. To detect its light the gravitational lensing effect of a galaxy cluster was used. That allowed to capture the extremely dim light of a total of 22 ancient galaxies using the Hubble and Spitzer space telescopes.

The early massive galaxies just discovered marked in red circles (Image ESO/UltraVISTA team. Acknowledgement: TERAPIX/CNRS/INSU/CASU)

An article published in the journal “Astrophysical Journal” describes the discovery of the oldest giant galaxies carried out thanks to ESO’s VISTA (Visible and Infrared Survey Telescope for Astronomy) telescope. A team of astronomers led by Karina Caputi of the Kapteyn Astronomical Institute at the University of Groningen, Netherlands, identified galaxies that existed when the universe was between 750 million and 2.1 billion years old. This result is surprising because the birth of galaxies so massive wasn’t expected so soon.

The galaxy MCG+01-02-015, also known as LEDA 1852 (Photo ESA/Hubble & NASA and N. Grogin (STScI), Acknowledgement: Judy Schmidt)

The galaxy MCG+01-02-015, also known as LEDA 1852, got photographed using the Hubble Space Telescope’s Advanced Camera for Surveys (ACS) instrument. The special characteristic of this galaxy is that it’s extremely isolated. Generally, galaxies are part of clusters which are in turn part of larger formations, bonded together in structures called galactic filaments, formations at a really huge scale. Among these filaments, however, there are cosmic voids in which sometimes there may be a lonely galaxy.

The galaxy cluster MACS J0416.1–2403 observed by the Hubble Space Telescope (Image NASA, ESA and the HST Frontier Fields team (STScI))

An international team led by the astronomer Hakim Atek of the Ecole Polytechnique Fédérale de Lausanne, Switzerland, used the Hubble Space Telescope to observe over 250 dwarf galaxies that existed between 600 and 900 million years after the Big Bang. It’s one of the largest samples of dwarf galaxies discovered so far dating back to such a remote era and allows us to look into the universe at a young age providing useful information to understand its evolution.