Based on observations from the Swift spacecraft, NASA has identified a new source of super bright X-rays emanating from the galaxy NGC 7090.
The object named NGC 7090 ULX3 is so bright that each of its X-rays emits a million times more radiation than our Sun at all wavelengths. General super bright X-ray (ULX) sources are known to be more powerful than any stellar process in the universe and only weaker than active galactic nuclei. Even so, their nature remains a great mystery.
Normally, each galaxy has only one ULX, but some special cases like NGC 7090 can contain more than that. This spiral galaxy 31 million light-years away from Earth is previously known to have up to two sources of super-bright X-rays, NGC 7090 ULX1 and NGC 7090 ULX2.
In a new observation from NASA’s Swift spacecraft, researchers from the UK University of Cambridge led by Dominic Walton reported discovering another ULX inside the NGC 7090 with a maximum brightness of 6 x. 10 ^ 39 erg / s (erg is a unit of measure for energy and mechanical work).
According to a report in arXiv magazine on November 17, NGC 7090 ULX3 has been operating continuously for more than 7 months. Most of the time, it had a relatively constant brightness of 0.1 x 10 ^ 39 erg / s and had only recently switched to super-bright under the Swift’s observations.
The astronomers emphasize such time-proportional change suggesting that NGC 7090 ULX3 could be a pulsar system. However, they have not detected any significant signal pulses from this source.
“We are still uncertain about the power supply for the NGC 7090 ULX3, so more observations are needed to fully understand the true nature of the system,” the team concluded.