N V Krishnendu, Tamara Evstafyeva, Aditya Vijaykumar, William E East, Rimo Das, Sayantani Datta, Nils Siemonsen, Nami Uchikata, Poulami Dutta Roy, Anuradha Gupta, Ish Gupta, Syed U Naqvi, Manuel Piarulli, Muhammed Saleem, Elise M Sänger, Pratyusava Baral, Sajad A Bhat, Thomas A Callister, Mattia Emma, Carl-Johan Haster
Several theoretical proposals describe horizonless compact objects that can mimic black holes in their gravitational wave signatures; however, their spin-induced quadrupole moments (SIQMs) may reveal their distinct nature. Using the tight bounds on the SIQM of GW241011, we place constraints on the nature of its primary. Across exotic compact object models considered in this Letter, we find that rotating boson stars with quartic self-interactions cannot explain the nature of the primary, whereas models of sufficiently large compactness, C≳0.24, may still be viable contenders.