When this happens, it's possible that not all of their central black holes will have merged yet. In one scenario, if two of these supermassive black holes undergo a merger where the production of gravitational energy is uneven, this can impart a directional kick to the post-merger product.Īn alternative road to ejection occurs if one or more galaxy mergers happen in relatively quick (in astronomical terms) succession. There are two ways this can lead to an ejection. As a result, the supermassive black holes of the pre-merger galaxies will eventually run into each other. This is inevitable due to two observations: Almost all galaxies seem to have a supermassive black hole at their core, and most galaxies are built by multiple mergers. One possible explanation for that movement is that the galaxy ejected a supermassive black hole. Putting everything together, it appears that the streak started forming about 40 million years ago, and its tip has been progressively moving away from the galaxy at about 1,600 kilometers a second since. In this case, the streak remained thin throughout its entire length.Ī look at the emission of the stars present in the streak suggests that, in general, the stars get younger as you move down the streak away from the galaxy. While the supermassive black holes at the center of galaxies can emit jets of material that long (and even longer), those jets tend to spread out as they get farther from the galaxy. The researchers estimate that the streak is about 200,000 light-years long. "Not having encountered something quite like this before in our own images or in the literature, we decided to include the feature in the observing plan for a scheduled Keck run." Advertisementīased on the redshift of light from the object, both it and the galaxy are roughly the same distance from Earth, suggesting that the two are related. You can almost hear echoes of those days in astronomers' description of seeing the smear across one of Hubble's images: "an almost-straight, thin streak was readily apparent in a visual assessment of the data quality."Ī close look revealed that the streak extended toward a somewhat odd-looking galaxy. What is that?īack in the days of film cameras, when it was sometimes possible to go months or even years between taking a photo and getting it developed, it wasn't unusual to pick up your newly developed snapshots and find yourself wondering what it was you had taken a picture of. If this is right, it will be the first instance of this behavior we've ever seen. Its liberation likely resulted from two additional supermassive black holes, all brought together by a merger of galaxies. They're still not certain, but the best explanation appears to be the wake left behind by a supermassive black hole that has been shot free of the galaxy that used to host it. So, a team of researchers decided to figure out what the long, thin smear might represent. But the streak, in this case, was in an image taken by the Hubble Space Telescope, which is not affected by the schmutz that daily life leaves on Earth-bound hardware. If you saw a similar streak in one of your photos, you'd probably take a few moments to clean off the lens. NASA, ESA, Leah Hustak reader comments 99 with
0 Comments
Leave a Reply. |