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29 lines
692 B
Python
29 lines
692 B
Python
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import numpy as np
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G = 42.981 #everything here is in Gadget-units
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def v_halo_from_mass(m_halo:int, L_box: float, N_res:int, m_particle:float):
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m_box = N_res**3 * m_particle
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rho_mean = m_box / (L_box ** 3)
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rho_halo = 200 * rho_mean
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r_halo = (3 * m_halo / (4 * np.pi * rho_halo)) ** (1/3)
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v_halo = np.sqrt(G * m_halo / r_halo)
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return v_halo
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v_result = v_halo_from_mass(m_halo=0.000067742, L_box=30.0, N_res=128, m_particle=0.1107263)
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print(v_result)
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# #Results:
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# 11.75 for 0.067742 * 10^10 / h
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# 6.21 for 0.01 ...
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# 2.88 for 0.001 ...
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# 1.17 for 0.000067742 ... (i.e. 10^6 M_sun halos, i.e. three orders of magnitude smaller than the 10^9 we started with)
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