2025ApJ...993..215W

As gravitational wave (GW) astronomy has entered an era of routine detections, it becomes increasingly important to precisely measure the physical parameters of individual events and infer population properties. Eccentricity is a key observable, suggesting that binaries form in a dense stellar environment through dynamical encounters. This work performs the first matched-filtering search for GWs from eccentric binary black holes (BBHs) covering the mass range [5, 200] M_⊙and eccentricity at 20 Hz up to 0.5 with a newly developed effective-one-body waveform model. Throughout the third observation run of LIGO, Virgo, and KAGRA, we identify 28 BBH events with a false alarm rate (FAR) below once per 100 yr, all of which were previously reported in the third Gravitational-wave Transient Catalog and fourth Open Gravitational-wave Catalog. Additional candidates with FARs between once per 1 and 100 yr are also reported. We perform an injection campaign to characterize the sensitive volume time of our search pipeline. Assuming that none of the eccentric BBH events were missed by previous searches, our results provide constraints on the event rate of eccentric BBHs in the mass range [5, 30] M_⊙. For a 30-30 M_⊙ BBH with eccentricity 0.5, the event rate is limited to less than 0.06 Gpc^–3 yr^–1; this marks a 1 order of magnitude improvement for sensitive volume compared with the previous search with a minimally modeled algorithm without using templates.