A lonely Milky Way analog galaxy, too massive for its wall. The background image shows the circulation of dark matter (blue and green) and galaxies (here viewed as small yellow dots) in a thin piece of the cubic volume in which we expect to discover one of such rare enormous galaxies. Credit: Images: Miguel A. Aragon-Calvo, Simulation Data: Illustris TNG project (CC BY 4.0).
Milky Way Discovered To Be More Unique Than Previously Thought.
Is the Milky Way unique, or, at least, is it in a special location in deep space? A global group of astronomers has discovered that the answer to that question is yes, in a method not previously valued. A new research study reveals that the Milky Way is too huge for its “cosmological wall,” something yet to be seen in other galaxies. The new research is published in Monthly Notices of the Royal Astronomical Society.
A cosmological wall is a flattened arrangement of galaxies found surrounding other galaxies, defined by especially empty regions called spaces on either side of it. These voids appear to squash the galaxies together into a pancake-like shape to make the flattened plan. This wall environment, in this case, called the Local Sheet, influences how The Milky Way and close-by galaxies turn around their axes, in a more organized method than if we remained in a random place in the Universe, without a wall.
Generally, galaxies tend to be considerably smaller sized than this so-called wall. The Milky Way is found to be surprisingly enormous in contrast to its cosmological wall, a rare cosmic incident.
The background image reveals the distribution of dark matter (green and blue) and galaxies (here seen as small yellow dots) in a thin slice of the cubic volume in which we expect to discover one of such unusual massive galaxies. A cosmological wall is a flattened arrangement of galaxies discovered surrounding other galaxies, identified by particularly empty regions called voids on either side of it. Only a handful– about a millionth of all the galaxies in the simulation– were as “unique” as the Milky Way, i.e. both ingrained in a cosmological wall like the Local Sheet, and as huge as our home galaxy.
What we recently discovered is that other walls of galaxies in the Universe like the Local Sheet extremely hardly ever seem to have a galaxy inside them thats as huge as the Milky Way.”.
A Local Sheet Analogue in the Illustris TNG300 simulation, a flat wall of galaxies surrounding a Milky Way Analogue galaxy (big sphere at the center).
A Milky Way Analogue sitting at the center of a flat wall of smaller galaxies (grey spheres). The blue circles show range from the Milky Way Analogue in 1 Mpc periods. The background image shows the distribution of dark matter (green and blue) and galaxies (here viewed as tiny yellow dots) in a thin piece of the cubic volume in which we anticipate to find among such rare enormous galaxies. Credit: Images: Miguel A. Aragon-Calvo, Simulation Data: Illustris TNG task (CC BY 4.0).
The new findings are based on a modern computer simulation, part of the IllustrisTNG job. The team simulated a volume of deep space almost a billion light-years across which contains millions of galaxies. Just a handful– about a millionth of all the galaxies in the simulation– were as “unique” as the Milky Way, i.e. both embedded in a cosmological wall like the Local Sheet, and as huge as our home galaxy.
According to the team, it may be essential to take into account the unique environment around the Milky Way when running simulations, to prevent a so-called “Copernican bias” in making clinical inference from the galaxies around us. This bias, explaining the successive removal of our special status in the nearly 500 years because Copernicus demoted the Earth from being at the center of the cosmos, would originate from assuming that we reside in a completely typical place in deep space. To replicate observations, astronomers in some cases assume that any point in a simulation such as IllustrisTNG is as excellent as any, but the teams findings indicate that it might be very important to utilize precise areas to make such measurements.
The Local Sheet, a flat wall of galaxies surrounding the Milky Way (suggested by a spiral pattern). The blue circles suggest distance from the Milky Way in 1 Mpc periods. Credit: Images: Miguel A. Aragon-Calvo, Simulation Data: Illustris TNG task.
” So, the Milky Way is, in a manner, unique,” said research study lead Miguel Aragón. “The Earth is really clearly special, the only home of life that we understand. Its not the center of the Universe, or even the Solar System. And the Sun is simply a normal star amongst billions in the Milky Way. Even our galaxy seemed to be simply another spiral galaxy amongst billions of others in the observable Universe.”.
” The Milky Way doesnt have a particularly unique mass, or type. There are lots of spiral galaxies that look roughly like it,” Joe Silk, another of the researchers, stated. “But it is uncommon if you take into account its surroundings. If you might see the nearest lots or so big galaxies easily in the sky, you would see that they all nearly lie on a ring, embedded in the Local Sheet. Thats a little bit special in itself. What we recently discovered is that other walls of galaxies in the Universe like the Local Sheet very rarely seem to have a galaxy inside them thats as enormous as the Milky Way.”.
A Local Sheet Analogue in the Illustris TNG300 simulation, a flat wall of galaxies surrounding a Milky Way Analogue galaxy (big sphere at the center). The blue circles indicate range from the main galaxy in 1 Mpc intervals. Credit: Images: Miguel A. Aragon-Calvo, Simulation Data: Illustris TNG project.
” You may need to travel a half a billion light years from the Milky Way, past numerous, many galaxies, to discover another cosmological wall with a galaxy like ours,” Aragón said. He includes, “Thats a number of hundred times further away than the nearest large galaxy around us, Andromeda.”.
” You do have to be careful, though, choosing homes that qualify as unique,” Dr. Mark Neyrinck, another member of the group, stated. “If we included an unbelievably restrictive condition on a galaxy, such as that it should contain the paper we blogged about this, we would certainly be the only galaxy in the observable Universe like that. But we believe this too huge for its wall home is physically significant and observationally relevant sufficient to call out as truly being unique.”.
Reference: “The unusual Milky Way-local sheet system: implications for spin strength and positioning” by M A Aragon-Calvo, Joseph Silk and Mark Neyrinck, 23 December 2022, Monthly Notices of the Royal Astronomical Society.DOI: 10.1093/ mnrasl/slac161.
