Uninhabitable Galaxies?

[nstahl]

I apologize if this has been covered. I looked through recent threads and didn't find it.

Today's APOD mentions

NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massive black holes near the galaxy's center.

And http://antwrp.gsfc.nasa.gov/apod/ap060415.htm says

But M81 left M82 with violent star forming regions and colliding gas clouds so energetic the galaxy glows in X-rays.

So, my question is, is it too radioactive for life as we know it throughout such galaxies?

[astroton]

nstahl,

SETI's search for ET life continues. Galaxies obviously house many billion stars. There is vast interstellar space between stars. Consider that a Sun like star with planet like Earth is part of one of the spiral arms of the galaxy. If life has evolved on such a planet, the high-energy electromagnetic waves such as Gamma & X rays, would get absorbed by the atmosphere, pausing little threat to the life.

But, there are many buts, the big but is the condition where a star such as the Sun with Earth like planet can evolve with right condition for life to evolve. (ie. less dusty environment)

[Qev]

I've also wondered if there are galaxies that are too active for our sort of life to actually evolve in them. Either starburst galaxies, with massive star-formation rates (and the rapid supernova rate this leads to), or highly active galaxies with powerful, quasar-like cores.

I think, in both cases, our sort of life could probably still exist. It all depends on where in the galaxy one is located. Being tucked away in dusty spiral arms provides decent protection from galactic core activity, and supernovae still need to be very close to do any real harm to Earth-like planets. I'm pretty certain that our own galaxy has undergone some starburst-type activity sometime in the past, and we're here, so...

I'm generally optimistic on this subject, I guess.

[harry]

hello all
Hello nstahl
Some areas of star burst galaxies are too hot and the gravitational and the extreme radiation influence may make life difficult to evolve. But each galaxy has areas of calm that will give billions of years to evolution to occur.

I agree with you qev.