If the planet is tectonically active (in other words, it has active volcanism), then I can easily see this being feasible. Extremophiles on Earth already exist in under water vents, even in the absence of light.
In fact, entire ecosystems are supported by this, when you consider all the life that exists below the light layer of the oceans.
ok forgive me for sounding like a moron when it’s early in the morning and I’m damned tired
isn’t being geologically active influenced by the gravitational pull of nearby celestial bodies though? I vaguely recall how one of Jupiter’s moons was geologically active likely because of Jupiter’s gravitational influences affecting its insides (if not Jupiter, then a moon of another gas giant in our solar system). I figure that the fact that Earth has a stable orbit helps regulate its own tectonic activity, disallowing any sharp and quick changes in said activity. I’m wondering if, in contrast, a free-flying rogue planet would be in and out of too many different gravitational fields too quickly for life to start up and be able to adapt.
On some planets (or moons), gravitational tidal forces do input a lot of energy into the planet in order to maintain or heat up its interior, which is part of the reason why moons like Enceladus and Europa have evidence of sub-surface liquid water, given that they’re so far away from the sun.
But other planets, including our own, have their own heat.
As much as 50% of the heat our planet has internally came from its formation, the continued impacts from planetary accretion led to a significant amount of energy being input into Earth. The remaining 50% of the heat of Earth comes from the decay of radioactive elements.
As a result Earth’s tectonic activity is almost exclusively powered by the energy it has stored in itself. Its orbit around the sun doesn’t significantly add any energy into that system, even the orbit of the moon doesn’t have a great deal of effect on the crust.
That all being said, rogue planets tend to not travel fast enough to encounter too many stellar mass gravitational fields. Depending on its velocity (which would really depend on what sort of star it orbited when it was created, and how far it orbited from said star), it could take millions of years between encountering any significant gravitational fields.
ohhh okay yeah I got confused between tectonic activity and just plain heat generation I guess