Institute for Astronomy | University of Hawaii | 2018 Feb 01
[img3="The quiescent galaxy eMACSJ1341-QG-1 as seen by the Hubble Space Telescope. The yellow dotted line traces the boundaries of the galaxy's gravitationally lensed image. The inset on the upper left shows what eMACSJ1341-QG-1 would look like if we observed it directly, without the cluster lens. The dramatic amplification and distortion caused by the intervening, massive galaxy cluster (of which only a few galaxies are seen in this zoomed-in view) is apparent. Credit: Harald Ebeling, UH IfA"]http://www.ifa.hawaii.edu/info/press-re ... SJ1341.jpg[/img3][hr][/hr]Extremely distant galaxies are usually too faint to be seen, even by the largest telescopes. But nature has a solution -- gravitational lensing, predicted by Albert Einstein and observed many times by astronomers. Now, an international team of astronomers led by Harald Ebeling from the University of Hawaii has discovered one of the most extreme instances of magnification by gravitational lensing.
Using the Hubble Space Telescope (HST) to survey a sample of huge clusters of galaxies, the team found a distant galaxy, eMACSJ1341-QG-1, that is magnified 30 times thanks to the distortion of space-time created by the massive galaxy cluster dubbed eMACSJ1341.9-2441.
The underlying physical effect of gravitational lensing was first confirmed during the solar eclipse of 1919, and can dramatically magnify images of distant celestial sources, provided a sufficiently massive object lies between the background source and us, the observers.
Galaxy clusters, enormous concentrations of dark matter and hot gas surrounding hundreds or thousands of individual galaxies, all bound by the force of gravity, are valued by astronomers as powerful “gravitational lenses.” By magnifying the galaxies situated behind them, massive clusters act as natural telescopes that allow scientists to study faint and distant sources that would otherwise be beyond the reach of even the most powerful man-made telescopes.
“The very high magnification of this image provides us with a rare opportunity to investigate the stellar populations of this distant object and, ultimately, to reconstruct its undistorted shape and properties,” states team member Johan Richard of the University of Lyon, who performed the lensing calculations.
Although similarly extreme magnifications have been observed before, the discovery sets a new record for the magnification of a rare “quiescent” background galaxy -- one that, unlike our Milky Way, does not form new stars in giant clouds of cool gas. ...
Thirty-fold: Extreme Gravitational Lensing of a Quiescent Galaxy at z = 1.6 - H. Ebeling et al