The warm-hot intergalactic medium (WHIM) research area investigates the diffuse, highly ionized baryonic component of the cosmic web at temperatures of roughly 10⁵–10⁷ K, believed to host a substantial fraction of the “missing” baryons at low redshift. This field combines cosmological simulations with multiwavelength observations, particularly soft X-ray and far-ultraviolet spectroscopy, to detect weak absorption or emission signatures from ions such as O VI, O VII, and O VIII in filaments between galaxies. Research focuses on WHIM thermodynamics, metal enrichment, shock-heating processes, and its role in structure formation, baryon cycling, and feedback from galaxies and active galactic nuclei.
Stars and galaxies make up much of the universe's ordinary, observable matter. But for decades, scientists have wrestled with a cosmic conflict: There should be much more.
Astronomy
Jul 21, 2026
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So far, humanity has yet to find its first "exomoon"—a moon orbiting a planet outside of the solar system. But that hasn't been for lack of trying. According to a new paper by Thomas Winterhalder of the European Southern ...
Astronomy
Jan 5, 2026
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Exploring one of science's most exciting frontiers, the book "Life in Space" bridges astrophysics and biology to uncover the conditions that make life possible—on Earth and beyond. Designed for students and general readers ...
Astronomy
Nov 12, 2025
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Previously described as playing astronomical "spot the difference," Kilonova Seekers asks the public to compare the latest images of a section of night sky to an image of the same section of space taken on previous nights. ...
Astronomy
Jul 1, 2025
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Astronomers have discovered a huge filament of hot gas bridging four galaxy clusters. At 10 times as massive as our galaxy, the thread could contain some of the universe's 'missing' matter, addressing a decades-long mystery.
Astronomy
Jun 19, 2025
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A new landmark study has pinpointed the location of the universe's "missing" matter, and detected the most distant fast radio burst (FRB) on record. Using FRBs as a guide, astronomers at the Center for Astrophysics | Harvard ...
Astronomy
Jun 16, 2025
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The fundamental building blocks for planet formation can exist even in environments with extreme ultraviolet radiation, according to a new study by an international collaboration led by Penn State astronomers.
Astronomy
May 21, 2025
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Much of the mass in the universe lies not in stars or galaxies, but in the space between them, known as the intergalactic medium. It is warm and even hot, and is called the "warm-hot intergalactic medium," or WHIM. It holds ...
