1/27/2024 0 Comments Free Edge Of GalaxyBut then we build ever better telescopes like ALMA, and find out that things are different than we expected. That means it’s hard to look this far away and see what’s going on, so we have to rely on our theory. The core of this galaxy is about 90,000 light-years distant. The nearest of these is the Sagittarius dwarf, a galaxy that is falling into the Milky Way Galaxy, having been captured tidally by the Galaxy’s much stronger gravity. Obviously, there’s more to learn about galaxies that exist at the edge of the observable Universe.Īs I mentioned, observing galaxies like this so far away is nearly impossible without gravitational lensing, which is random and sparsely spaced across the sky. Additional close companions have been found, all of them small and inconspicuous objects of the dwarf elliptical class. Clearly, the theoretical models are wrong, or at least (and more likely) incomplete. Like this one, it’s not understood how it can exist. Earlier in 2020 astronomers announced they found a disk galaxy at about the same distance, called the Wolfe Galaxy. Using the current dwarf galaxy population, we predict the edge of the Milky Way halo to be 292 +/- 61 kpc.Artwork depicting the Wolfe Galaxy, a massive disk galaxy similar to the Milky Way that was already well formed when the Universe was 1.5 billion years old. Finally, we show that the second caustic can also be identified in the phase-space distribution of dwarf galaxies in the Local Group. This can be identified in both radial density and radial velocity profiles, and should be measurable in future observational programmes. Curiously, the stellar distribution also has a clearly defined caustic, which, in most cases, coincides with the second caustic of the dark matter. However, the second caustic is less affected by the presence of a companion, and is a more useful definition for the boundary of the Milky Way halo. The splashback radius is ill defined in Local Group type environments where the halos of the two galaxies overlap. In the dark matter, we typically identify two caustics: the outermost caustic located at ~1.4r_200m corresponding to the "splashback" radius, and a second caustic located at ~0.6r_200m which likely corresponds to the edge of the virialized material which has completed at least two pericentric passages. Deason (Durham) and 7 other authors Download PDF Abstract:We use cosmological simulations of isolated Milky Way-mass galaxies, as well as Local Group analogues, to define the "edge" - a caustic manifested in a drop in density or radial velocity - of Galactic-sized haloes, both in dark matter and in stars. Download a PDF of the paper titled The Edge of the Galaxy, by Alis J.
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