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Suppose there is an object with the mass of the moon made entirely of dark matter. Suppose that somehow, it has the same mass density as the moon. By dark matter I mean matter that does not interact through the EM force, as well as the strong or weak force. Thus this object is bound entirely by the gravitational force.

Suppose this object is moving with an initial velocity, greater than the our solar system escape velocity. It's position is outside the solar system and its velocity vector direction is in the direction towards Earth.

At what point would the we be able to detect this object, with the equipment currently in operation on Earth? Is there a speed dependence on detection?

Would we be able to detect this object with gravitational wave detector?

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    $\begingroup$ Since it doesn't interact with light, it'd only be detected if it gravitationally lensed a background source (cf. this post and/or this post). You probably would be interested in MACHOs (not much on PSE about them though). $\endgroup$ – Kyle Kanos Nov 23 '15 at 18:52
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    $\begingroup$ Current theories of what dark matter might be favor choices that are unlikely to form a compact bound system at that scale. That's not definitive, of course, because we're still waiting on validation (or lack thereof) of these notion from actual detection of the constituents of the dark matter, but I thought it should be said. $\endgroup$ – dmckee --- ex-moderator kitten Nov 23 '15 at 19:07
  • $\begingroup$ @KyleKanos I'm about to edit my question, but I was also interested in how easily this object would be detected by gravitational wave detectors. $\endgroup$ – Viktor Nov 23 '15 at 19:52
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    $\begingroup$ Have we detected anything with gravitational wave detectors? $\endgroup$ – Kyle Kanos Nov 23 '15 at 20:01
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    $\begingroup$ Nothing with any confidence. $\endgroup$ – Viktor Nov 23 '15 at 20:02

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