Can direct collapse black holes launch gamma-ray bursts and grow to supermassive black holes?

The existence of black holes (BHs) of mass ∼109 M_⊙ at z ≳ 6 is a big puzzle in astrophysics because even optimistic estimates of the accretion time are insufficient for stellar-mass BHs of ∼10 M_⊙ to grow into such supermassive BHs. A resolution of this puzzle might be the direct collapse of supermassive stars with mass M ∼ 105 M_⊙ into massive seed BHs. We find that if a jet is launched from the accretion disk around the central BH, the jet can break out of the star because of the structure of the radiation-pressure-dominated envelope. Such ultralong gamma-ray bursts with duration of ∼10⁴ -10⁶ s and flux of 10^?11-10 ^-8erg s^-1cm ^-2 could be detectable by Swift. We estimate an event rate of ≲1 yr-1. The total explosion energy is ≳1055-1056 erg. The resulting negative feedback delays the growth of the remnant BH by about 70 Myr or evacuates the host galaxy completely.