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Prog. Theor. Phys. Vol. 47 No. 1 (1972) pp. 105-117

Dynamics of a Rotating Gaseous Ellipsoid in an Expanding Universe

Hidekazu Nariai and Mitsuaki Fujimoto^*

Research Institute for Theoretical Physics, Hiroshima University, Takehara, Hiroshima-ken
^*Department of Physics, Nagoya University, Nagoya

(Received July 26, 1971)

Abstract:

In order to assess the importance of the coupling of vorticity with the cosmic expansion in the process of galaxy formation, dynamical equations for a rotating gaseous ellipsoid with uniform density embedded in an expanding universe are derived on the basis of our Newtonian hydrodynamical equations rewritten so as to be useful in a rotating frame of reference relative to the cosmological one.
Numerical integrations of the equations are carried out on gaseous ellipsoids of the initial density ρ= 1.2ρ_β, 1.1ρ_β and 1.05 ρ_β, where ρ_β is the background density of the expanding universe. It is numerically shown that the ellipsoid becomes free from the expansion effects and starts to collapse when ρ/ρ_β attains the values of 5.4 to 5.6, depending on the configuration of the ellipsoid. The initial non-axisymmetric structure is amplified in the course of the gravitational collapse and finally reaches an infinitely thin elliptical disk. When the angular momentum is large, the gravitationally bound system cannot be established within 10¹⁰ years.
If the disk galaxy is formed from an initial density fluctuation with sufficient angular momentum, the initial velocities must be rather smaller than the general expanding velocity, otherwise the density fluctuation cannot rapidly become a gravitationally bound system in the plane perpendicular to the angular momentum vector. If this mechanism is correct, it would be indicative of the presence of primordial strong turbulence in the expanding universe.

URL : http://ptp.ipap.jp/link?PTP/47/105/
DOI : 10.1143/PTP.47.105

[ Full Text PDF : FREE ACCESS (770K) ] Citation: Plain Text BiBTeX EndNote(RIS) RSS

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References:

1. H. Nariai, Prog. Theor. Phys. 44 (1970), 110[PTP]; ibid. 45 (1971), 61[PTP].
2. D. Lynden-Bell, Astrophys. J. 139 (1964), 1195[CrossRef].
3. M. Fujimoto, Astrophys. J. 152 (1968), 523[CrossRef].
4. H. Nariai and Y. Ueno, Prog. Theor. Phys. 23 (1960), 305[PTP].
5. W. M. Irvine, Ann. of Phys. 32 (1965), 322[CrossRef].
6. T. Kihara, Publ. Astron. Soc. Jpn. 20 (1968), 220.
   T. Kihara and K. Sakai, Publ. Astron. Soc. Jpn. 22 (1970), 1.
7. K. Tomita, Prog. Theor. Phys. 42 (1969), 9[PTP]; ibid. 42 (1969), 978[PTP].
8. L. M. Ozernoi and A. D. Chernin, Sov. Astron. -AJ 11 (1968), 907; ibid. 12 (1969), 146.
   L. M. Ozernoi and G .V. Chibisov, Astrophys. Lett. 7 (1971), 201; Sov. Astron. -AJ 14 (1971), 615.
   H. Sato, T. Matsuda and H. Takeda, Prog. Theor. Phys. 43 (1970), 1115[PTP].
   K. Tomita, H. Nariai, H. Sato, T. Matsuda and H. Takeda, Prog. Theor. Phys. 43 (1970), 1511[PTP].

Citing Article(s) :

1. Progress of Theoretical Physics Vol. 47 No. 3 (1972) pp. 832-844 :

   Hydrodynamical Equations for a Collapsing Object with Spherical Symmetry in Terms of the Scalar-Tensor Theory of Gravity

   Hidekazu Nariai

2. Progress of Theoretical Physics Vol. 49 No. 4 (1973) pp. 1195-1204 :

   Hydrodynamic Calculations of Spherical Gravitational Collapse in the Scalar-Tensor Theory of Gravity

   Takuya Matsuda and Hidekazu Nariai

3. Progress of Theoretical Physics Vol. 50 No. 2 (1973) pp. 472-487 :

   On the Generatin of Sound from the Primordial Turbulence in an Expanding Universe

   Hidekazu Nariai

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