Added a maximum threshold of 1000 km/s for Disberg & Mandel (2025) LOGNORMAL kicks, matching paper

[ilyamandel]

No description provided.

[jeffriley]

Approved with a couple of questions:

(i) on line 3911 you have the comment

"makes it possible to adjust if p_Rand is too low, to avoid getting stuck"

but on line 3914 you reduce rand. Does the comment correctly/completely capture what you mean?

(ii) should the threshold value of 1000.0 be a constant defined in constants.h (named something like DISBERG_MANDEL_MAX_KICK)? Then the 1001.0 in line 3910 can just be (e.g.) DISBERG_MANDEL_MAX_KICK + 1.0.

EDIT: also, rand = 0.99 * rand; can just be rand *= 0.99; (more succinct, and not too obscure...)

[pauldisberg]

I ran COMPAS v03.20.06 with ./COMPAS -n 100000 --mode SSE --kick-magnitude-distribution LOGNORMAL. From the results I selected the NS-forming SNe with SN_Type==1 and in the attached figure I plot a CDF of the values of "Applied_Kick_Magnitude" (which is exactly equal to "Drawn_Kick_Magnitude").

For v<900 km/s it exactly follows our log-normal distribution, if it is not normalized between 0 and 1000 km/s. Between 900 and 1000 km/s, there is a clear feature in the COMPAS results that makes them deviate from the log-normal and make the total distribution normalized for v<1000 km/s. Could it be that the threshold of 1000 km/s is currently causing all kicks with v>1000 km/s to be projected on the region between 900 and 1000 km/s? That is, in the PDF there is a clear peak between at v>900 km/s, so I believe something is not going right with the normalization. (This feature is, e.g., not present in the figure @SimonStevenson made in #1404.)

[pauldisberg]

Figure made with the updated v3.20.06 (similarly to the one described above, but with -n 10000 and both the LOGNORMAL and the MAXWELLIAN distributions). Looks as intended, approved.

[ilyamandel]

Thank you, @pauldisberg and @jeffriley .

I was also taking advantage of this PR to do a bit of work on the Matlab post-processing, which doesn't need to be reviewed. Done with that for the day, so merging in.