29 research outputs found
On the Canonical Formalism for a Higher-Curvature Gravity
Following the method of Buchbinder and Lyahovich, we carry out a canonical
formalism for a higher-curvature gravity in which the Lagrangian density is given in terms of a function of the salar curvature as . The local Hamiltonian is obtained by a
canonical transformation which interchanges a pair of the generalized
coordinate and its canonical momentum coming from the higher derivative of the
metric.Comment: 11 pages, no figures, Latex fil
High Excitation Molecular Gas in the Galactic Center Loops; 12CO(J =2-1 and J =3-2) Observations
We have carried out 12CO(J =2-1) and 12CO(J =3-2) observations at spatial
resolutions of 1.0-3.8 pc toward the entirety of loops 1 and 2 and part of loop
3 in the Galactic center with NANTEN2 and ASTE. These new results revealed
detailed distributions of the molecular gas and the line intensity ratio of the
two transitions, R3-2/2-1. In the three loops, R3-2/2-1 is in a range from 0.1
to 2.5 with a peak at ~ 0.7 while that in the disk molecular gas is in a range
from 0.1 to 1.2 with a peak at 0.4. This supports that the loops are more
highly excited than the disk molecular gas. An LVG analysis of three
transitions, 12CO J =3-2 and 2-1 and 13CO J =2-1, toward six positions in loops
1 and 2 shows density and temperature are in a range 102.2 - 104.7 cm-3 and
15-100 K or higher, respectively. Three regions extended by 50-100 pc in the
loops tend to have higher excitation conditions as characterized by R3-2/2-1
greater than 1.2. The highest ratio of 2.5 is found in the most developed foot
points between loops 1 and 2. This is interpreted that the foot points indicate
strongly shocked conditions as inferred from their large linewidths of 50-100
km s-1, confirming the suggestion by Torii et al. (2010b). The other two
regions outside the foot points suggest that the molecular gas is heated up by
some additional heating mechanisms possibly including magnetic reconnection. A
detailed analysis of four foot points have shown a U shape, an L shape or a
mirrored-L shape in the b-v distribution. It is shown that a simple kinematical
model which incorporates global rotation and expansion of the loops is able to
explain these characteristic shapes.Comment: 59 pages, accepted to PAS
Third quantization of -type gravity
We examine the third quantization of -type gravity, based on its
effective Lagrangian in the case of a flat Friedmann-Lemaitre-Robertson-Walker
metric. Starting from the effective Lagrangian, we execute a suitable change of
variable and the second quantization, and we obtain the Wheeler-DeWitt
equation. The third quantization of this theory is considered. And the
uncertainty relation of the universe is investigated in the example of
-type gravity, where . It is shown, when the time is late
namely the scale factor of the universe is large, the spacetime does not
contradict to become classical, and, when the time is early namely the scale
factor of the universe is small, the quantum effects are dominating.Comment: 9 pages, Arbitrary constants in (4.19) are changed to arbitrary
functions of . Conclusions are not changed. References are added.
Typos are correcte
Temperature and Density in the Foot Points of the Molecular Loops in the Galactic Center; Analysis of Multi-J Transitions of 12CO(J=1-0, 3-2, 4-3, 7-6), 13CO(J=1-0) and C18O(J=1-0)
Fukui et al. (2006) discovered two molecular loops in the Galactic center and
argued that the foot points of the molecular loops, two bright spots at both
loops ends, represent the gas accumulated by the falling motion along the
loops, subsequent to magnetic flotation by the Parker instability. We have
carried out sensitive CO observations of the foot points toward l=356 deg at a
few pc resolution in the six rotational transitions of CO; 12CO(J=1-0, 3-2,
4-3, 7-6), 13CO(J=1-0) and C18O(J=1-0). The high resolution image of 12CO
(J=3-2) has revealed the detailed distribution of the high excitation gas
including U shapes, the outer boundary of which shows sharp intensity jumps
accompanying strong velocity gradients. An analysis of the multi-J CO
transitions shows that the temperature is in a range from 30-100 K and density
is around 10^3-10^4 cm^-3, confirming that the foot points have high
temperature and density although there is no prominent radiative heating source
such as high mass stars in or around the loops. We argue that the high
temperature is likely due to the shock heating under C-shock condition caused
by the magnetic flotation. We made a comparison of the gas distribution with
theoretical numerical simulations and note that the U shape is consistent with
numerical simulations. We also find that the region of highest temperature of
~100 K or higher inside the U shape corresponds to the spur having an upward
flow, additionally heated up either by magnetic reconnection or bouncing in the
interaction with the narrow neck at the bottom of the U shape. We note these
new findings further reinforce the magnetic floatation interpretation.Comment: 40 pages, 23 figures, accepted by PASJ on Vol.62 No.