Scientists May Have Detected the First Exoplanets in Another Galaxy,
It stands to reason that if there are exoplanets orbiting stars in our own galaxy, then there would also be exoplanets in other galaxies. However, other galaxies are too far away to detect exoplanets by any of the means we currently have. Now researchers from the University of Oklahoma claim to have spotted exoplanets in another galaxy using a technique called gravitational microlensing. These planets seem to have rather odd behavior, though.
In our galaxy, we look for exoplanets by observing the stars they orbit. We can detect small wobbles in the star as planets move around them, but this only works for larger planets. The transit method monitors stars for small dips in luminance from planets passing in front of them. This can detect smaller planets, but not all solar systems are oriented in such a way that planets pass in front of the star from our perspective. Gravitational microlensing is a completely different approach, predicted by general relativity. Just like a glass lens can magnify an object, the bending of space by gravity can amplify distant energy sources.
The lensing comes from an active galaxy with a black hole (known as a quasar) about 3.8 billion light years away. The intense gravity from the quasar bends light toward the Milky Way, bringing previously unseen objects into view. The team used the Chandra X-ray Observatory to scan the galaxy (called RXJ1131-1231, in the center of the above image), finding signals that could be planets.
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