Category Astronomy/Space

Dark matter may come in two flavors—finally explaining why its signals appear in some galaxies but vanish in others. A mysterious glow of gamma rays at the center of the Milky Way has long hinted at dark matter, but the lack of similar signals in smaller dwarf galaxies has cast doubt on that idea. Now, researchers propose a bold twist: dark matter might not be a single particle at all, but a mix of two different types that must interact with each other to produce detectable signals.

Sometimes, not seeing somet...

Supermassive black holes are among the most enigmatic objects in the universe. They typically weigh millions or even billions of times the mass of the sun and sit at the centers of most large galaxies. At the heart of the Milky Way lies Sagittarius A*, our galaxy’s supermassive blackhole, with a mass of about four million suns. But these black holes do not emit light, so astronomers can only detect them indirectly through their effects on nearby stars and gas. Artist’s depiction of a supermassive black hole tearing apart a star, with roughly half of the stellar debris flung back into space while the remainder forms a glowing accretion disk around the black hole. Credit: DESY, Science Communication Lab

In a study published in The Astrophysical Journal Letters, Eric Coughlin, assista...

Astronomers analyzing gravitational-wave data from the LIGO-Virgo-KAGRA Collaboration have reported that merging binary black holes fall into three distinct categories. The study shows that the three subpopulations have their own characteristic masses, spin behavior, and merger rate that may be linked to different dominant formation mechanisms. The paper outlining their results was submitted to the preprint server arXiv on March 18.

A mix of three
The data in the fourth gravitational-wave catalog (GWTC-4), released by the LIGO-Virgo-KAGRA collaboration, included more than 150 detected black hole mergers...

Earth may be habitable because it got unbelievably lucky with its chemistry from the very start.

Earth may have won a cosmic chemistry lottery. Researchers found that during the planet’s earliest formation, oxygen had to be in an extremely narrow “Goldilocks zone” for two life-essential elements, phosphorus and nitrogen, to stay where life could use them. Too much or too little oxygen, and those ingredients could be lost or trapped deep inside the planet. This could reshape the search for life by showing that water alone is not enough.

Life cannot begin on a planet unless certain chemical elements are available in large enough amounts. Two of the most important are phosphorus and nitrogen...