Asymmetry Made Audible: Mode Content of the Unequal-Mass Merger GW190412 and What Its Ringdown Can Separate

GW190412, with a mass ratio near four to one, was the first merger in which higher angular modes were clearly present in the signal. Asymmetry excites modes that equal-mass mergers suppress, so this paper computes the expected ringdown mode content of its remnant, in particular the relative excitation of the 330 mode against the fundamental, and asks whether that content makes the event a better or worse spectroscopy target than an equal-mass event of the same loudness. The progenitor mass ratio is 3.75 and the symmetric mass ratio is 0.166, well below the equal-mass value of 0.25. The remnant, at 37 source-frame solar masses (42.6 in the detector frame) and spin 0.43, rings fundamentally at 340.8 Hz with a 2.41 ms damping time, and its 330 mode sits at 544.6 Hz, a separation of 203.8 Hz. The adopted excitation scaling gives a 330-to-220 amplitude ratio of 0.39 for this system against 0.28 at equal mass, an enhancement factor of 1.40 bought by the asymmetry. At mass ratio 3.75 the 330 excitation rises to 0.39 of the fundamental, an enhancement of 1.40 over equal mass, with the two modes at 340.8 Hz and 544.6 Hz in a remnant of 37 solar masses. This study is computed from stated assumptions and published catalogue values; it is simulated, not measured.