59 research outputs found
In-in formalism on tunneling background: multi-dimensional quantum mechanics
We reformulate quantum tunneling in a multi-dimensional system where the
tunneling sector is non-linearly coupled to oscillators. The WKB wave function
is explicitly constructed under the assumption that the system was in the
ground state before tunneling. We find that the quantum state after tunneling
can be expressed in the language of the conventional in-in formalism. Some
implications of the result to cosmology are discussed.Comment: 13 pages, 3 figure
The critical radiation intensity for direct collapse black hole formation: dependence on the radiation spectral shape
It has been proposed that supermassive black holes (SMBHs) are originated
from direct-collapse black holes (DCBHs) that are formed at z gtrsim 10 in the
primordial gas in the case that H2 cooling is suppressed by strong external
radiation. In this work, we study the critical specific intensity J^crit
required for DCBH formation for various radiation spectral shapes by a series
of one-zone calculations of a collapsing primordial- gas cloud. We calculate
the critical specific intensity at the Lyman-Werner (LW) bands J^crit_LW,21 (in
units of 10^-21 erg s^-1 Hz^-1 sr^-1 cm^-2) for realistic spectra of metal-poor
galaxies. We find J^crit is not sensitive to the age or metallicity for the
constant star formation galaxies with J^crit_LW,21 = 1300-1400, while J^crit
decreases as galaxies become older or more metal-enriched for the instantaneous
starburst galaxies. However, such dependence for the instantaneous starburst
galaxies is weak for the young or extremely metal-poor galaxies: J^crit_LW,21 =
1000-1400 for the young galaxies and J^crit_LW,21 approx 1400 for the extremely
metal-poor galaxies. The typical value of J^crit for the realistic spectra is
higher than those expected in the literature, which affects the estimated DCBH
number density n_DCBH. By extrapolating the result of Dijkstra, Ferrara and
Mesinger, we obtain n_DCBH sim 10^-10 cMpc^-3 at z = 10, although there is
still large uncertainty in this estimation.Comment: 11 pages, 6 figures, submitted to MNRA
- …