(ORDO NEWS) — For the first time, astrophysicists have been able to calculate the initial mass and size of a dwarf galaxy that was torn apart by a collision with our Milky Way galaxy billions of years ago.
Reconstruction of the original dwarf galaxy, whose stars today line the “tidal stream” in our Galaxy today, will help scientists understand the formation of galaxies like the Milky Way and estimate the distribution of dark matter in our Galaxy.
“We ran simulations that take this huge stellar stream, rewind its evolution back several billion years, and as a result, we were able to observe what it looked like before it fell into the Milky Way,” said Heidi Newberg (Heidi Newberg) , Professor of Physics, Astrophysics and Astronomy, Rensselaer Polytechnic Institute, USA.
“We now have data-driven measurements, and this is an important first step in using this information to detect dark matter in our Milky Way galaxy.”
Billions of years ago, this dwarf galaxy and other small galaxies in the vicinity of the Milky Way were pulled in by the gravity of our larger galaxy. As each dwarf galaxy merged with our Galaxy, the stars of these small galaxies were stretched out by “tidal forces” similar to the gravitational forces that cause the tides on Earth.
These tidal forces distorted the shape of the galaxy and eventually tore it apart, causing the galaxy’s stars to stretch out into a long “tidal stream” running through the Milky Way.
Such mergers between galaxies with a tidal gap are quite common, and Newberg believes that “immigrant stars” from tidal streams make up the majority of the stars in the galactic halo, a spherical “cloud” of stars surrounding the spiral arms of the central disk.
Studying the positions and velocities of stars in tidal streams provides valuable information about the gravitational field of the Milky Way and makes it possible to establish the distribution of dark matter in our Galaxy, the author notes.
The reconstruction of this dwarf galaxy required a lot of computing power and was carried out using the distributed supercomputer MilkyWay@Home, created from many personal computers of volunteers around the world.
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