80 citations · 440 across the 45 of their papers we have counts for
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Scaling Relations for Collision-less Dark Matter Turbulence
Akika Nakamichi, Masahiro Morikawa
Many scaling relations are observed for self-gravitating systems in the universe. We explore the consistent understanding of them from a simple principle based on the proposal that…
Gravitational Fugacity as the seed of self-organized violent relaxaton process toward Local Virial relation
Yasuhide Sota, Osamu Iguchi, Tohru Tashiro +1
We propose the self-organized relaxation process which drives a collisionless self-gravitating system (SGS) to the equilibrium state satisfying local virial (LV) relation. During t…
Cosmic structures via Bose Einstein condensation and its collapse
Takeshi Fukuyama, Masahiro Morikawa, Takayuki Tatekawa
We develop our novel model of cosmology based on the Bose-Einstein condensation. This model unifies the Dark Energy and the Dark Matter, and predicts multiple collapse of condensat…
An Interpretation of Flat Density Cores of Clusters of Galaxies by Degeneracy Pressure of Fermionic Dark Matter: A Case Study of Abell 1689
Tadashi Nakajima, Masahiro Morikawa
Flat density cores have been obtained for a limited number of clusters of galaxies by strong gravitational lensing. This paper explores the possibility that the degeneracy pressure…
Local virial relation for self-gravitating system
Osamu Iguchi, Yasuhide Sota, Akika Nakamichi +1
We demonstrate that the quasi-equilibrium state in self-gravitating -body system after cold collapse are uniquely characterized by the local virial relation using numerical simu…
Why is the Zel'dovich Approximation so Accurate?
A. Yoshisato, M. Morikawa, N. Gouda +1
Why does the Zel'dovich approximation (ZA) work well to describe gravitational collapse in the universe? This problem is examined by focusing on its dependence on the dimensionalit…
Relativistic Gross-Pitaevskii equation and the cosmological Bose Einstein Condensation
Takeshi Fukuyama, Masahiro Morikawa
We do not know 96% of the total matter in the universe at present. In this paper, a cosmological model is proposed in which Dark Energy (DE) is identified as Bose-Einstein Condensa…
Local virial relation and velocity anisotropy for collisionless self-gravitating systems
Y. Sota, O. Iguchi, M. Morikawa +1
The collisionless quasi-equilibrium state realized after the cold collapse of self-gravitating systems has two remarkable characters. One of them is the linear temperature-mass (TM…
Fully Degenerate Self-Gravitating Fermionic Dark Matter: Implications to the Density Profile of the Cluster of Galaxies A1689, and the Mass Hierarchy of Black Holes
Tadashi Nakajima, Masahiro Morikawa
Equilibrium configurations of weakly interacting fully degenerate fermionic dark matter are considered at various scales in the Universe. We treat the general situations for the gr…
Universal Non-Gaussian Velocity Distribution in Violent Gravitational Processes
O. Iguchi, Y. Sota, T. Tatekawa +2
We study the velocity distribution in spherical collapses and cluster-pair collisions by use of N-body simulations. Reflecting the violent gravitational processes, the velocity dis…
Bose Einstein Condensation as Dark Energy and Dark Matter
Masako Nishiyama, Masa-aki Morita, Masahiro Morikawa
We study a cosmological model in which the boson dark matter gradually condensates into dark energy. Negative pressure associated with the condensate yields the accelerated expansi…
Linear Temperature-Mass relation and Local virial relation: Two hypotheses for self-gravitating systems
Y. Sota, O. Iguchi, M. Morikawa +1
We propose two hypotheses which characterize the quasi-equilibrium state that realizes after a cold collapse of self-gravitating system. The first hypothesis is the linear temperat…
Is Galaxy Distribution Non-extensive and Non-Gaussian?
Akika Nakamichi, Masahiro Morikawa
Self gravitating systems (SGS) in the Universe are generally thought to be non-extensive, and often show long-tails in various distribution functions. In principle, these non-Boltz…
Negative skewness of radial pairwise velocity in the quasi-nonlinear regime: Zel'dovich approximation
A. Yoshisato, M. Morikawa, H. Mouri
According to N-body numerical simulations, the radial pairwise velocities of galaxies have negative skewness in the quasi-nonlinear regime. To understand its origin, we calculate t…
On the Power Spectrum Density of Gamma Ray Bursts
Motoko Suzuki, Masahiro Morikawa, Izumi Joichi
Gamma ray bursts (GRBs) are known to have short-time variability and power-law behavior with the index -1.67 in the power spectrum density. Reanalyzing the expanded data, we have f…
Origin of scaling structure and non-gaussian velocity distribution in self-gravitating ring model
Yasuhide Sota, Osamu Iguchi, Masahiro Morikawa +2
Fractal structures and non-Gaussian velocity distributions are characteristic properties commonly observed in virialized self-gravitating systems such as galaxies or interstellar m…
Galaxy Distributions and Tsallis Statistical Mechanics
Akika Nakamichi, Izumi Joichi, Osamu Iguchi +1
Large-scale astrophysical systems are non-extensive due to their long-range force of gravity. Here we show an approach toward the statistical mechanics of such self-gravitating sys…
Statistical Mechanics of Self--Gravitating System : Cluster Expansion Method
Osamu Iguchi, Tomomi Kurokawa, Masahiro Morikawa +4
We study statistical mechanics of the self--gravitating system applying the cluster expansion method developed in solid state physics. By summing infinite series of diagrams, we de…
Beyond Zel'dovich-Type Approximations in Gravitational Instability Theory --- Padé Prescription in Spheroidal Collapse ---
Takahiko Matsubara, Ayako Yoshisato, Masahiro Morikawa
Among several analytic approximations for the growth of density fluctuations in the expanding Universe, Zel'dovich approximation in Lagrangian coordinate scheme is known to be unus…
Accuracy of Nonlinear Approximations in Spheroidal Collapse --- Why are Zel'dovich-type approximations so good? ---
Ayako Yoshisato, Takahiko Matsubara, Masahiro Morikawa
Among various analytic approximations for the growth of density fluctuations in the expanding Universe, Zel'dovich approximation and its extensions in Lagrangian scheme are known t…
Late-Time Mild Inflation --- a possible solution of dilemma: cosmic age and the Hubble parameter ---
Takeshi Fukuyama, Mikiko Hatakeyama, Masae Miyoshi +2
We explore the cosmological model in which a late-time mild inflation is realized after the star formation epoch. Non-vanishing curvature coupling of a classical boson field yields…
Dynamics of Subcritical Bubbles in First Order Phase Transition
Tetsuya Shiromizu, Masahiro Morikawa, Jun'ichi Yokoyama
We derivate the Langevin and the Fokker-Planck equations for the radius of -symmetric subcritical bubbles as a phenomenological model to treat thermal fluctuation. The effect…