nbanik / baryonic-effects-on-pal5 Goto Github PK

explore effect of the bar on GD-1 and obtain the power spectrum which has presumably very low power.

Hi Nil,

Looking through your code again, I think I've found an issue with how the stripped (x,v) is computed using the perturbed progenitor, in this line:

_vxvv is in cylindrical coordinates, but vector addition in cylindrical coordinates is not just a simple component-wise addition. Easiest way to do this is probably to extract the rectangular coordinates, as

unp_orb=numpy.array([o.x(ts[-1]),o.y(ts[-1]),o.z(ts[-1]),-o.vx(ts[-1]),-o.vy(ts[-1]),-o.vz(ts[-1])])
pal5_orb_bar= numpy.array([pal5_bar.x(ts[-1]),pal5_bar.y(ts[-1]),pal5_bar.z(ts[-1]),-pal5_bar.vx(ts[-1]),-pal5_bar.vy(ts[-1]),-pal5_bar.vz(ts[-1])])
pal5_orb_nobar= numpy.array([pal5_nobar.x(ts[-1]),pal5_nobar.y(ts[-1]),pal5_nobar.z(ts[-1]),-pal5_nobar.vx(ts[-1]),-pal5_nobar.vy(ts[-1]),-pal5_nobar.vz(ts[-1])])

(note that I do the velocity fliiping explicitly here), then

pert_orb= unp_orb - pal5_orb_nobar + pal5_orb_bar

and then convert this cartesian coordinate set to cylindrical

pert_orb_RpZ= bovy_coords.rect_to_cyl(pert_orb[0],pert_orb[1],pert_orb[2])
pert_orb_vRpZ= bovy_coords.rect_to_cyl_vec(pert_orb[3],pert_orb[4],pert_orb[5]),pert_orb[0],pert_orb[1],pert_orb[2])
pert_orb=Orbit([pert_orb_RpZ[0],pert_orb_vRpZ[0],pert_orb_vRpZ[1],pert_orb_RpZ[2],pert_orb_vRpZ[2],pert_orb_RpZ[1]])

Please check this code before implementing it, because I've only written it, not tested it...

Compute how much the power spectrum of the perturbed Pal 5 will change if we include the effect of the bar on the Pal 5 progenitor.

Add time switch to turn the bar on/off during the evolution of the stream.

Explore the effects of varying Mbar = 5x10^9 and 2x10^10 Msun and add the results.

To simulate the growth of the bar over time, wrap it in Dehnen smoothing wrapper.