T Minus 4 Days - Your galaxy shouldn't exist
Galactic Cluster Collinder 2261 in the Milky Way, imaged by the European Southern Observatory's Very Large Telescope (VLT) atop Mount Stromlo. I miss Australia already, but Thursday friends at ESO sent me this press release.
"Using ESO's Very Large Telescope, an international team of astronomers has shown how to use the chemical composition of stars in clusters to shed light on the formation of our Milky Way. This discovery is a fundamental test for the development of a new chemical tagging technique uncovering the birth and growth of our Galactic cradle.
"The formation and evolution of galaxies, and in particular of the Milky Way - the 'island universe' in which we live, is one of the major puzzles of astrophysics: indeed, a detailed physical scenario is still missing and its understanding requires the joint effort of observations, theories and complex numerical simulations. ESO astronomer Gayandhi De Silva and her colleagues used the Ultraviolet and Visual Echelle Spectrograph (UVES) on ESO's VLT to find new ways to address this fundamental riddle."
Though we live in the Milky Way and see its band of stars at night, astronomers do not understand how our galaxy formed. It had been thought that the Milky Way formed from the merger of smaller galaxies. An international team led by astronomer Manuela Zoccalli, of the Pontifical Catholic University in Chile, has disproved that inferrence. Her observations show that stars in the galaxy’s central bulge have a different chemical composition than stars in the spiral arms. If the Milky Way had formed from collisions of smaller galaxies, stars of similar composition would be mixed together everywhere we look. Zoccalli’s observations also show that our galaxy’s central bulge formed in a remarkably short time, less than a billion years.
Every galaxy we have found, like our Milky Way, contains at its centre a massive Black Hole. Giant singularities very likely exist in Space without surrounding galaxies, but would be quite difficult to detect. Instruments like the Hubble Space Telescope and our Subaru Telescope atop Mauna Kea have found galaxies that existed only a few hundred million years after the Big Bang. They are so distant in Space/Time that their light has shifted into the infrared. In the distant past we have seen quasars and Active Galactic Nuclei, powerful objects each radiating more energy than a million galaxies. These primordial objects are powered by massive Black Holes.
Near the beginning of the Universe, not enough time had passed for Black Holes to evolve from stars. Primordial Black Holes could form by collapse of quantum fluctuations. In the immense densities near the Big Bang, fluctuations were big enough to form Black Holes without becoming matter first. Many scientists, notably Stephen Hawking, believe that Primordial Black Holes survive today.
The mass of a collapsing Black Hole is limited by a horizon distance, the distance light can travel in a given time. Previously it was thought that Primordial Black Holes would be tiny, because of light’s limited reach. If we consider that the speed of light was faster, the mass within the horizon was enormous. Primordial Black Holes could have formed of immense mass, seeding formation of galaxies around them. The massive Black Hole at the centre of our Milky Way may be older than the galaxy. This is yet another indication of a changing speed of light.
The Southern sky is endlessly fascinating. Here we can see the nearest stars and the galactic centre. Many amazing discoveries are being made by astronomers in Australia, Chile and Antarctica. Scientists should take their heads out of those computers and look at the sky. While they are at it, they can stop harassing woman scientists. We have a lot to contribute.