def __init__(self, n=1., Ie=1., I0=None, Re=1., rsamp=None, **kwargs) :
""" Parameters of the Sersic law: n, Ie, Re
n is adimensional and can be anything from 0 to infinity
It usually has values between 1 and 8 for real galaxies
Re in parsec
Ie in Lsun.pc-2 the surface brightness at 1 Re
or
I0 in Lsun.pc-2 the central surface brightness
bn is adimensional and derived from n
Other Parameters:
rhoL is in Lsun.pc-3
Ltot in Lsun
rho_average is also in Lsun/pc3
"""
self.n = nfloat(n)
self.Re = Re
self.bn = self.get_bn()
if I0 is None :
self.Ie = Ie
self.get_I0()
else :
self.I0 = I0
self.get_Ie()
## Compute the total 1D luminosity
self.get_Ltot()
## Compute some input numbers for the Prugniel-Simien function
if 'pPS97' in kwargs :
self.pPS97 = kwargs.pop('pPS97')
else :
self.pPS97 = 1.0 - 0.6097 / self.n + 0.05463 / (self.n * self.n)
self.rho0PS97 = self.I0 * self.bn**(self.n * (1. - self.pPS97)) \
* gamma(2. * self.n) / (2. * self.Re * gamma(self.n * (3. - self.pPS97)))
self.r, self.rre, self.Nr = self.get_radii(rsamp)
## We derive the projected Sersic profile (direct evaluation)
self.rhop = self.get_Sersic(self.r)
## we then derive the spatial luminosity profile from Simonneau et al
self.rhoL = self.get_rhoSersic(self.r)
## we then derive the spatial luminosity profile from Abel deprojection
self.rhoAbel = self.get_rhoAbel(self.r)
self.rhoPS97 = self.get_rhoPS97(self.r)
self.Mint = self.get_MintSersic(self.r)
self.MintPS97 = self.get_MintPS97(self.r)
self.MintAbel = self.get_MintAbel(self.r)
def get_bn(self, n=None) :
"""
Return the value of b_n, corresponding to a Sersic n index
b_n can be derived in two ways:
* a linear function of n using coefficients present in self._coef_bn_n
* a fraction representation using coefficients present in self._coef_bn_invn
The first function is used for n < 0.36, the second one for all other values of n
"""
if n is None : n = self.n
else :
n = nfloat(n)
self.n = n
if (n > 0.36) :
bn_poly = np.poly1d(self._coef_bn_invn)
return (2.0 * n + bn_poly(1. / n))
else :
bn_poly = np.poly1d(self._coef_bn_n)
return (bn_poly(n))
from pygme.utils.iodata import get_package_data
__version__ = '1.1.2 (August 21, 2013)'
#__version__ = '1.1.2 (August 14, 2013)'
#__version__ = '1.1.1 (August 30, 2012)'
#__version__ = '1.1.0 (March 3, 2012)'
## Version 1.1.3 : Fixing some docstrings
## Version 1.1.2 : Fixing bug in Integrated Luminosity
## Version 1.1.0 : small fix on the get_I0 function
######################################################################
## Some useful values
######################################################################
Ggrav = 0.0043225524 # value from Remco in (km/s)2. Msun-1 . pc
facPC = nfloat(pi / 0.648)
######################################################################
## Tabulated function to get deprojected Sersic ######################
## Derive the h1/2/3 functions
######################################################################
def hfunc_Abel(n) :
"""
Provides the parameters for an Abel integration of a Sersic function
It returns a set of factors which depends on the input Sersic n
"""
X = get_package_data("Abel_param.dat", asfile=False)
ndata = X[:,0]
nudata = X[:,1]
kdata = X[:,2]
a0data = X[:,3]