Astronomers create detailed map of almost 400,000 nearby galaxies

Using data from NSF's NOIRLab telescopes, astronomers have created a detailed digital atlas of nearly 400,000 nearby galaxies. The Siena Galaxy Atlas (SGA) is a treasure trove of information for researchers investigating everything from galaxy formation and evolution to dark matter and gravitational waves.

"Nearby large galaxies are important because we can study them in more detail than any other galaxies in the Universe; they are our cosmic neighbors. Not only are they strikingly beautiful, but they also hold the key to understanding how galaxies form and evolve, including our very own Milky Way galaxy," says John Moustakas, professor of physics at Siena College and SGA project leader.

The digital atlas includes data from three surveys completed between 2014 and 2017, called the DESI Legacy Surveys, which were carried out to identify galaxy targets for the Dark Energy Spectroscopic Instrument (DESI) survey. Data were collected at Cerro Tololo Inter-American Observatory (CTIO) and Kitt Peak National Observatory (KPNO) and at the University of Arizona's Steward Observatory.

The surveys captured images in both optical and infrared wavelengths to chart a total area of 20,000 square degrees - almost half of the night sky. The Siena Galaxy Atlas offers precise data on the locations, shapes and sizes of hundreds of thousands of relatively nearby large galaxies. Additionally, the data in this digital atlas achieves a new level of accuracy and it is also the first such resource to provide data on the light profiles of galaxies.

According to NOIRLab, SGA will enhance research into how patterns of star formation vary across different galaxies, the physical processes underlying the diverse array of morphologies that galaxies display, and how the distribution of galaxies is related to how dark matter is spread across the Universe. It will also help astronomers pinpoint the sources of transient signals like gravitational waves and understand the events that give rise to them.