On July 21 at 10 am, Seti Talks will be discussing the topic of "Could Rogue Planets Harbor Life". Supposedly there are 50 billion such planets in the Milky Way. I would think that the answer was obvious: no. So what is there to discuss?
There's also the possibility that a rogue giant planet may have a moon with a subsurface ocean of liquid water due to tidal heating in an orbit close enough to its parent planet. E.g. if Jupiter was a rogue planet its moon Europa could still harbor life because of tidal heating.
Around five percent of Earth-sized ejected planets with Moon-sized natural satellites would retain their satellites after ejection. A large satellite would be a source of significant geological tidal heating26.
26. Debes, John H.; Steinn Sigurðsson (20 October 2007). "The Survival Rate of Ejected Terrestrial Planets with Moons". The Astrophysical Journal Letters. 668 (2): L167–L170. arXiv:0709.0945
In short, if a rogue planet has enough internal heat and retains enough of that internal heat by a thick atmosphere or within a miles-deep ice crust, it could be warm enough for liquid water and thus possibly for Earth-like lifeforms.
here is a link to an article on the subject:
And an advanced civlization capable of building artifical habitats on lifeless worlds or in outer space could settle a rogue planet, providing their own energy source from nuclear fusion.
The discussion will focus on
the term rogue planet is an oxymoron, as it's missing the principle defining feature of a planet.
a Jupiter-sized body without a sun will be warmer than you would have thought. And they could be even larger, up to being brown dwarfs.
moons of such a body can be heated by tidal forces, without regard to whether there's a sun or not.