Hubble reveals a distant galaxy twice through a gravitational lens
A Hubble image released by NASA on 22 October shows one distant galaxy stretched into two arcs by a foreground galaxy’s gravity. Distances differ between the two: about 4.5 billion light-years for the lens galaxy, and about 8 billion for the background source. Detailed Hubble views are helping prepare methods for the Roman Space Telescope’s wider surveys.
Science··Morning
One background galaxy appears on both sides of the lens
NASA, the US space agency, released a Hubble Space Telescope view on 22 October in which a foreground galaxy turns one more distant galaxy into two visible arcs. For the nearer elliptical galaxy, the distance is about 4.5 billion light-years. For the background galaxy, the distance is about 8 billion light-years. Its light forms a large arc on one side and a smaller, reversed counterpart on the other. A prominent barred spiral galaxy elsewhere in the frame is separate from the lens.[1]
Bent light traces the intervening galaxy’s mass
The effect is gravitational lensing: the mass of the nearer galaxy bends and magnifies light passing it. Astronomers use the shape of the distortion to constrain how much mass lies in the foreground object. Comparing that total with its visible material helps investigate the contribution of dark matter, which is inferred through its gravitational effects. The image release describes this arrangement without presenting a new numerical dark-matter mass measurement.[1]
Hubble obtains sharp views of individual objects, mainly in ultraviolet and visible wavelengths, alongside a portion of the infrared range. NASA’s Nancy Grace Roman Space Telescope is designed to observe a much larger field, primarily in infrared. Researchers are using individual Hubble lens images to build a computer model for interpreting distortions in Roman’s future images. Hubble could then inspect selected Roman discoveries more closely. The newly released view is one preparatory example in that larger collection.[1]
