ランダウ共鳴が 与えるダークマターハロー密度 構造への影響. ○扇谷 豪 森 正夫 ( 筑波大 ). Contents. Introduction The Core-Cusp problem ( GO & Mori; arXiv1206.5412) Change of galactic potential Analytical model Results of simulations Summary & Discussion. Ishiyama et al. (2012). What is the Core - Cusp Problem ?.
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○扇谷 豪 森 正夫
Mass-density profile of DM halo
Observation vs Theory (CDM)
Constant : Core
log(ρ) [ 1010M☉kpc-3]
Divergent : Cusp
-1 0 1
van Eymerenet al. (2009)
See also Burkert (1995)
Navarro et al.(1997)
GO & Mori (2011)
Motivation: understand the mechanism for cusp flattening
1) Gas heating by supernovae
2) Gas expansion
3) Energy loss by radiative cooling
4) Contraction towards the center
5) Ignition of star formation again
Repetition of these processes
Change of potential ⇒ DM halo is affected gravitationally
⇒ Cusp to Core transition?
(A: strength, k: wavenumber, Ω: frequency)
Linearized continuity eq. and Euler eq.
Resonance occurs when the condition is satisfied
⇒efficient energy transfer
Gauss’s hyper-geometric function
DMhalo (N-body system):
NFWmodel(Navarro et al. 1997)
Baryon (external potential):
Property of DM halo
Oscillation period of the external force, T
T = 1,3,5,10 (0.2kpc)
The cusp-core transition and the resultant core scale depends on the oscillation period of the external potential, T.
Prediction of Core Scale
・Oscillation period T
Density profiles of DM halos
after several oscillation periods
Fourier spectrum of radial velocity
Peaks appear when ω=2π/T .
Each position of the peaks matches the core scale.
ω=nΩ→ Spectrum with peak (Resonance)
n=1 for T=1
n=1 for T=1
dynamical time oscillation period
McQuinn et al. (2010)
at core scale
(Oh et al. 2011)
Regarding as an oscillatory SFH,
T ~ 100Myr