Category Astronomy/Space

European astronomers have used the Atacama Large Millimeter Array (ALMA) and the James Webb Space Telescope (JWST) to observe a recently discovered giant disk galaxy known as ADF22.1. Results of the new observations, published April 8 on the arXiv preprint server, shed more light on the formation and evolution of this galaxy.

A unique laboratory
ADF22.1, also known as ADF22.A1, is a giant disk barred spiral galaxy residing in a protocluster known as SSA22 at a redshift of 3.09. It has an effective radius of some 22,800 light years and a stellar mass of about 100 billion solar masses...

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...