Planets Detected 3.8 Billion Light Years Away

The gravitational lens RX J1131-1231 galaxy can be seen at the centre, with four lensed background quasars (University of Oklahoma)

Note: It's actually one background quasar. Gravitational lenses normally produce multiple images.

Simulated gravitational lensing (black hole passing in front of a background galaxy).

https://en.wikipedia.org/wiki/File:Black_hole_lensing_web.gif

https://en.wikipedia.org/wiki/Gravitational_lens

The planets detected are near the lensing star according to the article.

Definitely impressive!

Going back to the source,

Abstract of the original paper:

"Previously, planets have been detected only in the Milky Way galaxy. Here, we show that quasar microlensing provides a means to probe extragalactic planets in the lens galaxy, by studying the microlensing properties of emission close to the event horizon of the supermassive black hole of the background quasar, using the current generation telescopes. We show that a population of unbound planets between stars with masses ranging from Moon to Jupiter masses is needed to explain the frequent Fe Kα line energy shifts observed in the gravitationally lensed quasar RXJ 1131–1231 at a lens redshift of z = 0.295 or 3.8 billion lt-yr away. We constrain the planet mass-fraction to be larger than 0.0001 of the halo mass, which is equivalent to 2000 objects ranging from Moon to Jupiter mass per main-sequence star."

I could be wrong but I'm thinking that what they are saying is that the iron (Fe) K alpha line radiation from the quasar is modified by the bodies that make up the lensing galaxy. The modification of the Fe Kα line indicates that there are estimated to be 2000 objects for every star that are too small to be stars (i.e. they are free planets ranging from moon size to Jupiter size).

http://iopscience.iop.org/article/10.3847/2041-8213/aaa5fb/meta

FYI, here is a copy of the actual paper:

https://arxiv.org/pdf/1802.00049.pdf

This paper describes the technique...

http://cds.cern.ch/record/630210/files/0307422.pdf

Interesting, but as the average spacing of galaxies is 1 million lightyears, I'm surprised planets haven't been found in one much closer to home. Any idea why?

The galaxy has to be lensing a quasar. Not too many of those.

Thanks, I thought there must be something that only works for vey distant galaxies. I suppose all the exoplanets found so far are in the Milky Way?

I believe you are correct, until now all microlensing planet search has been within our galaxy. 19 planets have been found in this way where one star passes in front of another one. The closer star acts as a lens and if a planet is present, the light curve is modified.

https://en.wikipedia.org/wiki/List_of_exoplanets_detected_by_microlensing

PLANET DETECTION THROUGH MICROLENSING

The microlensing process in stages, from right to left. The lensing star (white) moves in front of the source star (yellow) magnifying its image and creating a microlensing event. In the fourth image from the right the planet adds its own microlensing effect, creating the two characteristic spikes in the light curve.

http://www.planetary.org/explore/space-topics/exoplanets/microlensing.html

I think were a safe distance should they launch an attack.

Until they find that worm hole that leads to this part of the universe.

I know this is a big wow for astronomy physics science techie guys but how does this get me closer to obtaining the longer lasting light bulb ?