late_type_lognormal_size¶
- skypy.galaxies.morphology.late_type_lognormal_size(magnitude, alpha, beta, gamma, M0, sigma1, sigma2, size=None)[source] [edit on github]¶
Lognormal size distribution for late-type galaxies.
This function provides a lognormal distribution for the physical size of late-type galaxies, described by equations 12, 15 and 16 in [1].
- Parameters:
- magnitudefloat or array_like.
Galaxy magnitude at which evaluate the lognormal distribution.
- alpha, beta, gamma, M0: float
Model parameters describing the mean size of galaxies in [kpc]. (Equation 15).
- sigma1, sigma2: float
Parameters describing the standard deviation of the lognormal distribution for the physical radius of galaxies. (Equation 16).
- sizeint or tuple of ints, optional.
Output shape. If the given shape is, e.g., (m, n, k), then m * n * k samples are drawn. If size is None (default), a single value is returned if mean and sigma are both scalars. Otherwise, np.broadcast(mean, sigma).size samples are drawn.
- Returns:
- physical_sizenumpy.ndarray or astropy.Quantity
Physical distance for a given galaxy with a given magnitude, in [kpc]. If size is None and magnitude is a scalar, a single sample is returned. If size is ns, different from None, and magnitude is scalar, shape is (ns,). If magnitude has shape (nm,) and size=None, shape is (nm,).
References
[1]S. Shen, H.J. Mo, S.D.M. White, M.R. Blanton, G. Kauffmann, W. Voges, J. Brinkmann, I. Csabai, Mon. Not. Roy. Astron. Soc. 343, 978 (2003).