K-State physicists contribute to US Department of Energy research on dark energy and universe expansion

MANHATTAN — The universe is expanding, and Kansas State University physicists want to know why.

Lado Samushia, associate professor of physics in the College of Arts and Sciences, is part of a collaboration studying the mysterious force behind the universe’s accelerating expansion, referred to as dark energy.

The researchers are using the Dark Energy Spectroscopic Instrument, or DESI, located at the Kitt Peak National Observatory in Tucson, Arizona, to map more than 40 million galaxies, quasars and stars. The experiment is managed by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory.

The collaboration recently released its first batch of data — with nearly two million objects for researchers to explore — and published a set of papers related to the early data release. The papers include early measurements of galaxy clustering, studies of rare objects, and descriptions of the instrument and survey operations.

Hanyu Zhang, a K-State doctoral student in physics supervised by Samushia, is a lead author of the paper “The DESI One-Percent Survey: Exploring the Halo Occupation Distribution of Luminous Red Galaxies and Quasi-Stellar Objects with AbacusSummit.”

“Our team analyzed properties of two types of galaxies — luminous red galaxies and the galaxies that have quasi-stellar objects in their center — and saw very clearly that the luminous red galaxies gain mass and acquire fewer satellite galaxies with time,” said Zhang. “These insights provide valuable illumination on the physics involved in the evolution of massive galaxies.”

DESI uses 5,000 robotic positioners to move optical fibers that capture light from objects millions or billions of light-years away. It is the world’s most powerful multi-object survey spectrograph and can measure light from more than 100,000 galaxies in one night. That light tells researchers how far away an object is, allowing them to build a 3D cosmic map.

As the universe expands, it stretches light’s wavelength, making it redder. This wavelength stretch is known as redshift. The farther away the galaxy, the bigger the redshift is. DESI specializes in collecting redshifts that can be used to solve some of astrophysics’ biggest puzzles: what is dark energy, and how has it changed throughout the universe’s history?

To learn more about DESI and this research, view the Berkeley Lab news release.

Derek Nester
Derek Nesterhttp://www.sunflowerstateradio.com
Derek Nester was born and raised in Blue Rapids and graduated from Valley Heights High School in 2000. He attended Cowley College in Arkansas City and Johnson County Community College in Overland Park studying Journalism & Media Communications. In 2002 Derek joined Taylor Communications, Inc. in Salina, Kansas working in digital media for 550 AM KFRM and 100.9 FM KCLY. Following that stop, he joined Dierking Communications, Inc. stations KNDY AM & FM as a board operator and fill-in sports play-by-play announcer. Starting in 2005 Derek joined the Kansas City Chiefs Radio Network as a Studio Coordinator at 101 The Fox in Kansas City, a role he would serve for 15 years culminating in the Super Bowl LIV Championship game broadcast. In 2020 he moved to Audacy, formerly known as Entercom Communications, Inc. and 106.5 The Wolf and 610 Sports Radio, the new flagship stations of the Kansas City Chiefs Radio Network, the largest radio network in the NFL. Through all of this, Derek continues to serve as the Digital Media Director for Sunflower State Radio, the digital and social media operations of Dierking Communications, Inc. and the 6 radio stations it owns and operates across Kansas.


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