Consistency check casts doubt on evolving dark energy

Cosmologists have long struggled to determine whether the universe's accelerating expansion is being driven by a simple cosmological constant, or whether dark energy's influence is evolving over time. In a new analysis published ...

eROSITA discovers a 'changing-look' Seyfert galaxy

Astronomers have tracked a dramatic "changing-look" active galactic nucleus (AGN) whose central supermassive black hole appeared to switch off and then rapidly reignite. The galaxy, HE 1237−2252, dimmed in X-rays by a factor ...

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