A few calculations for FRB 171020 [v3]



In [1]:

    
# imports
import numpy as np

from astropy import units as u
from astropy.cosmology import Planck15
from astropy import constants

from ne2001 import density
from ne2001.density import NEobject

from pyigm.cgm.models import ModifiedNFW, MB04, YF17

Coords



In [2]:

    
FRB_l = 36.4
FRB_b = -53.6

$\rm DM_{\rm disk}$

ne2001



In [3]:

    
ne = density.ElectronDensity()#**PARAMS)



In [4]:

    
DM_disk = ne.DM(FRB_l, FRB_b, 100.)
DM_disk









    Out[4]:





$37.420666 \; \mathrm{\frac{pc}{cm^{3}}}$

$\rm DM_{\rm halo}$

Halo properties



In [5]:

    
Mhalo = np.log10(1.5e12)
f_hot = 0.75  # Allows for disk + ISM
c = 7.7

Simple Model



In [6]:

    
# MB
mb04 = MB04(log_Mhalo=Mhalo, f_hot=f_hot, c=c)
DM_halo = mb04.Ne_Rperp(8*u.kpc)  # This is approximate.  Should do proper l,b but may make little difference
DM_halo/2  # Only get 1/2 for our Galaxy









    



rhoV normalized to 0.00017228356281820233 1 / cm3 to give M_b=240000000000.00006 solMass






    Out[6]:





$66.099776 \; \mathrm{\frac{pc}{cm^{3}}}$

Better model



In [7]:

    
params = dict(F=1., e_density=1.)
model_ne = NEobject(mb04.ne, **params)



In [8]:

    
DM_halo2 = model_ne.DM(FRB_l, FRB_b, mb04.r200.to('kpc').value)
DM_halo2









    Out[8]:





$69.066446 \; \mathrm{\frac{pc}{cm^{3}}}$

Inner 10kpc



In [9]:

    
DM_halo2_10 = model_ne.DM(FRB_l, FRB_b, 10.)
DM_halo2_10









    Out[9]:





$7.9316968 \; \mathrm{\frac{pc}{cm^{3}}}$

$\rm DM_{\rm host}$ -- This is Halo gas only



In [10]:

    
Mhost = np.log10(1e10)
f_hot_host = 0.5  # Allows for 50% blow-out
c = 7.7



In [11]:

    
mb04_host = MB04(log_Mhalo=Mhost, f_hot=f_hot_host, c=c)
DM_host = mb04_host.Ne_Rperp(1*u.kpc)
DM_host/2  # Only get 1/2









    



rhoV normalized to 7.048521943833164e-05 1 / cm3 to give M_b=1600000000.0 solMass






    Out[11]:





$9.769291 \; \mathrm{\frac{pc}{cm^{3}}}$

D$_{\rm IGM}$

Mean density



In [12]:

    
rhob = Planck15.Ob0 * Planck15.critical_density0
rhob









    Out[12]:





$4.1890501 \times 10^{-31} \; \mathrm{\frac{g}{cm^{3}}}$



In [17]:

    
n_b = rhob / 1.3 / constants.m_p
n_b.decompose().cgs









    Out[17]:





$1.926524 \times 10^{-7} \; \mathrm{\frac{1}{cm^{3}}}$

Scale down by baryons in stars, compact objects



In [23]:

    
neff_b = n_b * 0.7 # Approximate

Do it



In [19]:

    
DM_IGM = 50 * u.pc / u.cm**3



In [24]:

    
D_IGM = DM_IGM / neff_b
D_IGM.to('Mpc')









    Out[24]:





$370.76399 \; \mathrm{Mpc}$



In [ ]: