File:SDP 81 (26294109950).png

English: This is the Hubble image of SDP.81 to give some context to an Einstein ring in the news lately. Near the center of the image is a large, reddish galaxy with radio contours of the Einstein ring in white. I am pretty sure I got the alignment right or I wouldn't be posting it, but if anyone sees something wrong please comment! The radio contours were obtained from Figure 4 of this paper. (I hope no one minds me using the outlines from their graphic here!)

I don't think you'd ever guess the lensing is there by looking at the Hubble data alone. It's invisible. Ok, this ESO article says the Einstein ring is "hardly visible" in the Hubble image, and it does look like a lensing arc, but at the same time those arcs don't seem to line up with the radio data from the paper. I might be in over my head here trying to figure this out and got it wrong, but I can't tell for sure!

Being such a small smudge in a very large sky, one gets the impression these astronomers have been looking far and wide for evidence of dark matter galaxies. The idea here is that the observed gravitational lensing can apparently only be explained by the presence of a clump of dark matter in the halo of SDP.81.

The usual artifacts present in the WFC3/IR channel have been made visibly unobtrusive either by filling them with an average color or, in the case of the larger one or ones overlapping a star or galaxy by conservative use of cloned data. The color saturation has been augmented so that human eyes can perceive it.

Red: hst_12194_01_wfc3_ir_f160w_sci Green: Pseudo Blue: hst_12194_01_wfc3_ir_f110w_sci

North is NOT up. It is 38° counter-clockwise from up.