Red Nuggets are small galaxies that are packed with a large number of red stars that were originally detected by the Hubble Space Telescope (HST) back in 2005. They are very ancient relics of the first massive galaxies. The environment of red nuggets is generally consistent with that of elliptical galaxies. Most red nuggets have collided and merged with other galaxies. However, some have managed to escape that ordeal.
Red Nuggets acquired their nickname not only as a result of their size and color, but also as a result of how precious their discovery was for curious astronomers. This is because the discovery of these small galaxies challenged accepted theories of galactic formation.
Blue Nugget galaxies are thought to be the progenitors of Red Nuggets. Blue Nuggets are stream-nourished, star-forming, ancient systems that are quenched inside-out wiithin the inner parsec and dissipatively compacted into red nuggets at their peak formation rate. Galaxies that sport more mass generally quench sooner than galaxies that are not as richly endowed, and contain low amounts of mass because galaxies with small quantities of mass attempt to quench several times. Blue Nuggets apparently quench at a totally constant stellar surface density. The compaction occurs as a result of a ferocious episode of inflow involving (primarily small) mergers and counter-rotating streams or recycled gas. It is also frequently associated with extreme disc instability. The quenching occurs because of the extremely high rate of star formation and feedback from supernovae–and also, possibly, as a result of the high gas density in the center of the red nugget.
Data obtained from Chandra has revealed that the central black hole of Mrk 1216 has suppressed star birth. This is because of the black hole’s heat, and also because it devours surrounding gas. Thus the interesting question arises: how could Mrk 1216 possibly be packed so densely with stars? Results indicate that the answer to this question may be that Mrk 1216 and other red nuggets contain unused stellar “fuel” enabling them to give birth to their unusually large stellar population. However, there is another viable theory that proposes that red nuggets are really young elliptical galaxies, therefore evolving the same way that they do.
A team led by Dr. Ivana Damjanov discovered more than 600 red nuggets in the Sloan Digital Sky Survey (SDSS) database. These small galaxies were overlooked for such a long time because their size made them appear to be stars in the images. However, examination of their spectra revealed their true rare and precious nature.
Before Dr. Damjanov and her colleagues sifted through the SDSS database, no astronomer could detect the elusive galaxies after their original discovery back in 2005.
Billions and billions of starlit galaxies perform their wild ancient dance within the observable Universe. The observable, or visible, Universe is the relatively small domain of our much more vast Cosmos that we are able to observe, because whatever may or may not exist beyond the horizon of the visible Universe, has not had sufficient time to wend its way to us since the Big Bang almost 14 billion years ago. This is because of the universal speed limit set by light. No known signal can travel faster than light in a vacuum. The Universe presents us with the most profound of mysteries, and it keeps it secrets well. In June 2019, astrophysicists using data obtained from the Chandra X-ray Space Telescope, managed to probe into one of these many mysteries. The Chandra scientists identified a strange galaxy that has been isolated for billions of years, and it contains more dark matter packed into its heavy heart than expected.
The bizarre galaxy, named Markarian 1216 (Mrk 1216) hosts stars that are within 10% of the age of the Universe. This indicates that Mrk 1216 is almost as old as the observable Universe itself. The astronomers have discovered that it has experienced a different evolution than garden-variety galaxies, both in respect to its stars and the invisible and transparent dark matter that, through the powerful force of gravity, holds the galaxy together.
Dark matter is a mysterious substance that accounts for about 85% of the matter in the Cosmos, and about 25% of its total energy density–although it has never been observed directly. Most of the dark matter is thought to be an exotic form of undiscovered non-atomic matter that does not interact with light or any other form of electromagnetic radiation, which is the reason why it is invisible. However, its ghostly presence is revealed in a variety of astrophysical observations, including its gravitational effects on objects that can be observed. Dark matter is believed to be the stuff that keeps galaxies from falling apart. Indeed, the primary indication of its existence is based on calculations that demonstrate that without it galaxies would fragment, instead of rotating. Without the existence of this mysterious transparent material, it is also likely that galaxies would not have formed in the first place–or even move the way that they do. Other lines of evidence include observations of gravitational lensing from the cosmic microwave background (CMB) radiation–which is the relic radiation left over from the Big Bang itself. Furthermore, the reality of this ghostly material is suggested from astronomical observations of the observable Universe’s current structure, from the birth and evolution of galaxies, from the location of mass during galactic smash-ups, and from the way that galaxies move within galaxy clusters.