Astronomers have created the largest ever 3D map of a million distant galaxies obscured by the Milky Way’s neighboring dwarf galaxies, the Magellanic Clouds.
The Magellanic Clouds form irregularly galaxies It is an amazing feature of the Southern Hemisphere sky visible to the naked eye. But the brightness of these dwarf galaxies, combined with the fact that they occupy a large area of the night sky, means that Milky WayOur view of many distant galaxies is obscured by our neighbors. So when astronomers observe billions of galaxies in the universeThey tend to avoid this part of the sky.
“The Magellanic Clouds are beautiful galactic companions but, unfortunately, they obscure some of our view of distant objects,” said Keele University astronomer and map team member Jessica Craig. permit (Opens in a new tab). “Our work helps overcome this, and in the process we help fill in the gaps in our map of the universe.”
Connected: This magnificent image from the Hubble Space Telescope shows turquoise waves pulsing through the Milky Way’s satellite
Craig and her colleagues tackled this problem by imaging the Magellanic Clouds at such high resolution that they could search the gaps between the two images. stars that make up these galaxies. To make these images, the team turned to the Visible and Infrared Scanning Telescope for Astronomy (VISTA), based at the Paranal Observatory in Chile.
But these increasingly distant “hidden” galaxies are harder to see because they appear fainter and redder than due to the dust in the Magellanic Clouds. To explain this effect, the team turned to a radio telescope, the Australian Square Kilometer Survey Pathfinder Array (GASKAP), which can peer through dust between Earth and distant galaxies. The GASKAP data allowed scientists to create a detailed map of the gas and dust in the Magellanic Clouds and thus calculate how much “reddening” these factors cause the galaxies that obscure them.
The Small Magellanic Cloud obscures galaxies in the southern hemisphere. (Image: ESA/Hubble and Digitized Sky Survey 2)
Due to the sheer number of light sources in images of the Magellanic Cloud, the human eye alone cannot distinguish distant galaxies from nearby objects. But stars change position while distant galaxies stay in the same place, so the team was able to use the data to map the stars. Gaia Observatory To correctly classify each light source.
Astronomers used a second technique to confirm the distinction between distant galaxies and relatively nearby stars. As the universe expands, as more distant galaxies move away from Earth, the wavelength of light from those galaxies expands. The longer wavelengths of visible light are red, so astronomers describe this lengthening redshift.
The more distant an object is, the faster it is moving away, so the redder its light appears, the redder the more distant galaxies become than the stars. By taking color into account, the team can remove stars from their data further.
Finally, the astronomers applied machine learning and artificial intelligence to line up the galaxies and create a 3D map of approximately one million galaxies.
Craig Presentation of team results In mid-July at the National Astronomy Meeting held at the University of Warwick in the United Kingdom
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