Faintest Galaxies Ever Seen Explain The ‘Missing Link’ In The Universe
“By warping space, the light from background objects gets magnified, revealing extraordinarily faint galaxies.
The only problem? The cluster itself is closer and overwhelmingly luminous, making it impossible to tease out the distant signals.
Until now. Thanks to a superior new technique devised by Rachael Livermore, light from the foreground cluster galaxies can be modeled and subtracted, revealing faint, distant galaxies never seen before.”
One of the biggest puzzles in science is exactly how the Universe became transparent to visible light. Neutral atoms – cosmic dust – blocks visible light, and yet before there were stars, that’s all we had. According to theory, it should be large numbers of small, faint, ultra-distant galaxies that made it transparent, but they’ve never been seen. However, thanks to the combined power of the Hubble Space Telescope, gravitational lensing and a new foreground light-removal technique, galaxies 100 times fainter thank the ones visible in the Hubble eXtreme Deep Field – the longest-exposure image ever – have now been revealed. These galaxies, seen in two Frontier Fields’ clusters so far, are the ‘missing link’ needed to explain reionization.
A mere 20,000 light-years from the Sun lies NGC 3603, a resident of the nearby Carina spiral arm of our Milky Way Galaxy. NGC 3603 is well known to astronomers as one of the Milky Way’s largest star-forming regions. The central open star cluster contains thousands of stars more massive than our Sun, stars that likely formed only one or two million years ago in a single burst of star formation. In fact, nearby NGC 3603 is thought to contain a convenient example of the massive star clusters that populate much more distant starburst galaxies.Surrounding the cluster are natal clouds of glowing interstellar gas and obscuring dust, sculpted by energetic stellar radiation and winds.
Recorded by the Hubble Space Telescope, the image spans about 17 light-years.
Image Credit: NASA, ESA, Hubble Heritage(STScI/AURA)-ESA/ Hubble Collaboration;
Acknowledgment: J. Maiz Apellaniz (Inst. Astrofisica Andalucia) et al., & Davide de Martin (skyfactory.org)
The NASA/ESA Hubble Space Telescope celebrates the holiday season with a striking image of the planetary nebula NGC 5189. The intricate structure of the stellar eruption looks like a giant and brightly coloured ribbon in space.
NASA, ESA and the Hubble Heritage Team (STScI/AURA)
(NASA) Warped Spiral Galaxy ESO 510-13 Image Credit: Hubble Heritage Team (STScI/AURA), C. Conselice (U. Wisconsin/STScI) et al., NASA
How did spiral galaxy ESO 510-13 get bent out of shape? The disks of many spirals are thin and flat, but not solid. Spiral disks are loose conglomerations of billions of stars and diffuse gas all gravitationally orbiting a galaxy center. A flat disk is thought to be created by sticky collisions of large gas clouds early in the galaxy’s formation. Warped disks are not uncommon, though, and even our own Milky Way Galaxy is thought to have a small warp. The causes of spiral warps are still being investigated, but some warps are thought to result from interactions or even collisions between galaxies. ESO 510-13, pictured above digitally sharpened, is about 150 million light years away and about 100,000 light years across.
This massive cluster of galaxies (1E 0657-558) creates gravitational lens distortions of background galaxies in a way that has been interpreted as strong evidence for the leading theory: that dark matter exists within. Different recent analyses, though, indicate that a less popular alternative – modifying gravity– could explain cluster dynamics without dark matter, and provide a more likely progenitor scenario as well. Currently, the two scientific hypotheses are competing to explain the observations: it’s invisible matter versus amended gravity. The duel is dramatic as a clear Bullet-proof example of dark matter would shatter the simplicity of modified gravity theories. For the near future, the battle over the Bullet cluster is likely to continue as new observations, computer simulations, and analyses are completed. The featured image is a Hubble/Chandra/Magellan composite with red depicting the X-rays emitted by hot gas, and blue depicting the suggested separated dark matter distribution.
Image Credit: X-ray: NASA/CXC/CfA/ M. Markevitch et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/ D.Clowe et al. Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.
Celestial bubble SNR B0509-67.5 1 is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud, a small galaxy about 160 000 light-years from Earth; NASA/ESA/Hubble heritage team STScI/AURA/ J. Hughes