Your Celestial Companion

Astrophysicists have completed ASTRID, the largest cosmological hydrodynamic simulation ever run, tracing the universe from the cosmic dawn ($z=99$) down to the present day ($z=0$). By resolving 166 billion particles across 815 million light-years, ASTRID unveils how supermassive black holes co-evolve with galaxies and sculpt the cosmic web.

Scientists have uncovered the first robust evidence of a black hole and neutron star crashing together while orbiting in an oval path, challenging long-standing assumptions about cosmic pair formation. Most neutron star-black hole pairs are expected to adopt circular orbits long before merging, their orbits slowly rounded out by the constant emission of gravitational waves over millions of years.

Far from the warmth of any star, moons orbiting rogue gas giants might harbor oceans of liquid water—and potentially complex life—for billions of years. Liquid water is considered essential for life. Surprisingly, however, stable conditions that are conducive to life could exist far from any sun.

Astronomers have witnessed the birth of a highly magnetized, spinning neutron star, confirming it as the hidden engine behind some of the brightest exploding stars in the cosmos. Superluminous supernovae—which can be 10 or more times brighter than run-of-the-mill supernovae—have puzzled astronomers since their discovery in the early 2000s. They were thought to result from the explosion of very massive stars, perhaps 25 times the mass of our sun, but they stayed bright much l