Famous oddball quasar isn't X-ray weak after all, astronomers say

Astronomers have been studying the quasar PHL 1811 for over two decades, considering it a prototype of a rare class of objects known as "intrinsically X-ray weak" quasars. These quasars were thought to produce unusually little X-ray radiation, setting them apart from other quasars. However, a recent observation by the Einstein Probe spacecraft in 2024 has shed new light on this phenomenon. The spacecraft captured a bright X-ray flare from PHL 1811, prompting a re-examination of the object's behavior.

By combining the new data with more than 20 years of archival observations, researchers were able to gain a more comprehensive understanding of PHL 1811's X-ray output. The study, published in The Astrophysical Journal on July 28, reveals that the quasar's X-ray activity is more variable than previously thought. The bright flare observed by the Einstein Probe spacecraft suggests that PHL 1811 may not be as X-ray weak as initially believed. This finding has significant implications for our understanding of quasars and their role in the universe.

The new study on PHL 1811 highlights the importance of continued observations and data analysis in refining our understanding of celestial objects. The discovery of the bright X-ray flare and the re-evaluation of PHL 1811's X-ray output demonstrate the value of long-term monitoring and the potential for unexpected findings to challenge existing theories. As research continues to uncover new insights into the behavior of quasars, our understanding of the universe will continue to evolve.