Sign error in MarginalM1PowerlawPopulation rvs
alpha_m
should be negated before being passed to powerlaw_rvs
in https://git.ligo.org/daniel.wysocki/bayesian-parametric-population-models/-/blob/b91120c12d6198dd266e8d3c073568f76bdac872/src/pop_models/astro_models/building_blocks/powerlaw.py#L784