First Planet detected in Andromeda Galaxy M31?

Quite blurry kind of detection, but possible hint of a substellar companion orbiting a star in another galaxy *emphasis mine*

http://exoplanet.eu/star.php?st=PA-99-N2

Listed in EPE amongst unconfirmed objects.

Paper here:

The anomaly in the candidate microlensing event PA-99-N2

Quote :

ABSTRACT. The light curve of PA-99-N2, one of the recently announced microlensing candidates toward M31, shows small deviations from the standard Paczyński form. We explore a number of possible explanations, including correlations with the seeing, the parallax effect, and a binary lens. We find that the observations are consistent with an unresolved red giant branch or asymptotic giant branch star in M31 being microlensed by a binary lens. We find that the best-fit binary lens mass ratio is ~1.2 × 10-2, which is one of the most extreme values found for a binary lens so far. If both the source and lens lie in the M31 disk, then the standard M31 model predicts the probable mass range of the system to be 0.02-3.6 Mso (95% confidence limit). In this scenario, the mass of the secondary component is therefore likely to be below the hydrogen-burning limit. On the other hand, if a compact halo object in M31 is lensing a disk or spheroid source, then the total lens mass is likely to lie between 0.09 and 32 Mso, which is consistent with the primary being a stellar remnant and the secondary being a low-mass star or brown dwarf. The optical depth (or, alternatively, the differential rate) along the line of sight toward the event indicates that a halo lens is more likely than a stellar lens, provided that dark compact objects comprise no less than 15% (or 5%) of halos.

We could even merge discussion in Unconfirmed Planets Thread

ZOMG!! And I was told that nobody could ever discover a plant outside the Milky Way (shame on them).

Shame indeed.

Still though, this candidate is still unconfirmed. To confirm it, we would need for it to undergo another microlensing event. Microlensing events are notoriously a one-time only event for a single object. For another event to occur, it could take a very, very long time.

I think it's safe to say that PA-99-N2 b will keep the same "unconfirmed" status as that other extragalactic planet, Q 0957+561 b. The original extrasolar visions site has a page on it here. May even be safe to go so far as to say that you might as well forget about PA-99-N2 b. I fully expect that if it is ever detected again, it will be with radial velocity of the host star, some point in the distant future with perhaps a crater-sized lunar telescope.

But that's no excuse not to throw the planet into Celestia with fictional information about the orbit and play around with speculations

Still... It cosmic to think of planets in our big sister galaxy. It makes you think, are there any Andromedans out there that look at the huge bared galaxy that we live in and say "I wonder if there is life there?"

The Q0957+561 detection was not of a single planet but implied many planets in the lens galaxy (YGKOW G1, not the quasar). Secondly it was not of a single object, but the implication of a large population of ~10^-5 solar mass objects (paper is here) and implies that the bulk of the dark matter in the galaxy is composed of rogue planets. This seems somewhat suspicious.

Oooo.... I was not aware of that. Thanks for that paper!
If rogue planets can explain the dark matter in YGKOW G1, why would this not be detected in other lensing galaxies?

As far as I am able to tell, a similar thing was proposed for the Einstein Cross lensing system. Not sure it has stood up to scrutiny though, but it's someone else's turn to trawl SIMBAD...