Error on quasi universal fit parameters

[lshetusuleiman]

Dear developpers,
In Spacetime.py, a quasi universal relation on the dimensionless mass quadrupole uses fits established in Algendy & Morsink 2014.
However, it seems that the hard coded value of beta1 is not the one reported in Table 1 (page 4) of Algendy & Morsink 2014, see copy of this table:

It should be (according to the paper) 0.4454 and it is coded 0.4554.

xpsi/xpsi/Spacetime.py

Line 202 in a3fd654

return temp + 0.4554 * 4.0 * self.epsilon * self.zeta / 3.0

This is in lines ~ 190 of Spacetime.py. Can you confirm that this is a typo ?

Also in the same function, does someone knows why there is no minus sign in front of the 0.11, value for the a2 parameter ?

xpsi/xpsi/Spacetime.py

Line 200 in a3fd654

temp = self.epsilon * 0.11 / (self.zeta * self.zeta)

And finally, I am a bit puzzled by this line

xpsi/xpsi/Spacetime.py

Line 201 in a3fd654

temp -= self.a * self.a / (self.r_g * self.r_g)

that I cannot seem to find in the paper of Algendy & Morsink. Would you happend to know what it does ?

Kind regards,
Lami Suleiman.

[thjsal]

Well noticed! I think those seem indeed typos. Luckily, I think we are usually not using this function q() (to be confirmed though). Anyway, makes sense to fix it (or remove if not needed at all). And I am not sure about the puzzling line. Should look more into that.

[thjsal]

The actual oblateness relations we use are linked in this issue:

#359

[thjsal]

Okay, I checked that this function is never called in the GitHub fast-example and thus very likely not in any of our other analyses so far.

[sguillot]

I think it should be fixed anyway - we don't use it, but other users might.

The fix to line 200 and 202 are trivial, but I do not understand where line 201 of spacetime.py comes from. Any ideas?