Mass-gap extreme mass ratio inspirals

In this work, we propose a new subclass of extreme-mass-ratio-inspirals (EMRIs): mass-gap EMRIs, consisting compact object in the lower mass gap $\ensuremath{\sim}(2.5\ensuremath{-}5)\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ and massive black hole (MBH). The (MGO) may be primordial or produced from delayed supernova explosion. We calculate formation rate EMRIs both (dry) loss-cone channel (wet) active galactic nucleus disk by solving Fokker-Planck-type equations for phase-space distribution. dry channel, EMRI is strongly suppressed compared to stellar-mass holes (SBHs) as result segregation effect. wet suppression roughly equal ratio SBHs over MGOs, because migration speed an proportional its mass. find that much more promising produce observable spaceborne gravitation wave detectors. (Non)detection used distinguish different explosion mechanisms constrain abundance around MBHs.