GW190521 may be an intermediate mass ratio inspiral

Understand

GW190521 is the first confident observation of a binary black hole merger with total mass $M > 100\,\mathrm{M}_{\odot}$.

• Given the lack of observational constraints at these masses, we analyze GW190521 considering two different priors for the binary's masses: uniform in mass ratio and source-frame total mass, and uniform in source-frame component masses.
• For the uniform in mass-ratio prior, we find that the component masses are $m_1^{\mathrm{src}} = 168_{-61}^{+15}\,\mathrm{M}_{\odot}$ and $m_2^{\mathrm{src}} = 16_{-3}^{+33}\,\mathrm{M}_{\odot}$.
• The uniform in component-mass prior yields a bimodal posterior distribution.