This may look like the a poor recreation of the Eye of Sauron, but it’s actually a gravitational lens of one galaxy warping the light from another.
Back in 2014, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile discovered this lensing system, dubbed SDP.81. Gravitational lenses are a prediction of Einstein’s theory of general relativity that describes gravity as a space-time continuum - light traveling through space from a distant galaxy can be “bent” if it passes too close to a massive galaxy or galaxy cluster. When this happens along our line of sight, we see the closer galaxy surrounding by false imaged of the more distant galaxy. The shape and distribution of the false images depends on the mass of the closer galaxy (or galaxies).
The blue glow in the center of the image above is a relatively close galaxy around 3.5 billion light years away (as observed by the Hubble Space Telescope). The red arcs in the image are the false images of a more distant galaxy over 12 billion light years away (as observed by ALMA). Now, new analysis of how the light from this more distant galaxy was warped to make the arcs we see has revealed that there is a dark dwarf galaxy hiding just to the lower left of the center (as marked by a small white dot). But the white dot isn’t actually there in the Hubble images, so what’s going on?
Astronomers led by Yashar Hezaveh at Stanford University deduced that something massive enough to affect the shape of the red arcs has to be there. They think it could be a small, faint, dark-matter dominated galaxy in orbit around the visible blue galaxy, which is not uncommon at all since most galaxies should be surrounded by a collection of smaller ones. The biggest problem seems to be detecting them.
As Neal Dalal, another member of the team, states in the ALMA press release:
“This discrepancy between observed satellites and predicted abundances has been a major problem in cosmology for nearly two decades, even called a ‘crisis’ by some researchers… If these dwarf objects are dominated by dark matter, this could explain the discrepancy while offering new insights into the true nature of dark matter.”
Here’s some more geek from the week:
- Scientists have figured out how monarch butterflies keep track of time and space during migrations.
- An octopus in a New Zealand aquarium made a great escape from his tank to the sea.
- Inuits used to carve portable maps of coastlines and islands out of wood.
- You may think plants are harmless, but watch these vines take over New York City. [VIDEO]
- Did you catch the hole-in-one at the Masters last weekend? BECAUSE PHYSICS. [VIDEO]
- There’s physics in the can of mixed nuts you just bought! [VIDEO]
- Want to see water + cornstarch balloons get shot at in slo-mo? Yes, yes you do. [VIDEO]
- The science behind viral sharing, aka beneficial epidemics, (or how to make Fetch happen).
- From NASA to the car industry, hydrogen leaks are never good and this tape alerts you to potential danger.
- Check out this beautiful visualization highlighting some of the best photos of objects in our Solar System.
- Japan’s sent a spacecraft to Venus that took the long way, but just sent its first amazing images.
Keep on geeking!
@Summer_Ash, In-house Astrophysicist