Intermediate-mass black holes ( IMBHs : masses between 100 - 10 ^ { 6 } M _ { \odot } ) historically comprise of an elusive population compared to stellar-mass and supermassive BHs .
Recently IMBHs have started to be observed at the centers of low-mass galaxies .
We perform cosmological hydrodynamical simulations of ( 2 h ^ { -1 } ~ { } { Mpc } ) ^ { 3 } comoving boxes and investigate the growth and feedback of central IMBHs in dwarf galaxies ( DGs ) .
The earliest BHs appear at z \sim 18 - 25 , and grow thereafter by accreting gas and by merger with other BHs .
We find that , starting from 10 ^ { 2 } M _ { \odot } , it is possible to build up IMBHs of a few \times 10 ^ { 5 } -10 ^ { 6 } M _ { \odot } by z = 5 , when the BHs are seeded in halos less massive than 4 \times 10 ^ { 7 } M _ { \odot } .
The BH accretion rates increase with time , and reaches \dot { M } _ { BH } = ( 0.2 - 0.8 ) \dot { M } _ { Edd } for the massive IMBHs by z = 4 .
The star formation rate density ( SFRD ) evolution of the DGs ( stellar mass 10 ^ { 5 } -10 ^ { 8 } M _ { \odot } ) has a peak plateau between z = 4 - 6 .
Star formation is quenched between z = 9 - 4 .
The SFRD is reduced by factors up to 3 , when the BHs have grown to a few times 10 ^ { 5 } M _ { \odot } .
Even in the presence of stronger SN-driven mass ejection , the BHs continue to grow up to z \sim 6 , sustained by gas inflows driven by galaxy mergers and interactions in a cosmological environment .
Our conclusions , based on numerical simulation results , support the scenario that early feedback from IMBHs in gas-rich DGs at z = 5 - 8 can potentially solve several anomalies in the DG mass range within the concordance \Lambda CDM cosmological scenario ( 97 ) .
Our results suggest that IMBHs at DG centers grow faster than their host galaxies in the early Universe , and the resulting BH feedback turns the DGs and the BHs dormant .