http://arxiv.org/abs/2212.00807

Binary systems are ubiquitous and their formation requires two-body interaction and dissipation. In gaseous media, interactions between two initially unbound objects could result in gas-assisted binary formation, induced by a loss of kinetic energy to the ambient gas medium. Here we use analytic tools to derive the criteria for gas-assisted binary capture through gas dynamical friction dissipation. We validate them with few-body simulations and explore this process in different gas-rich environments, including gas-embedded stars in star forming regions (SFR), gas-enriched globular clusters, AGN disks and gaseous protoplanetary disks. We find that gas-assisted binary capture could be highly efficient in SFRs, potentially providing the main channel for the formation of stellar binaries. It could also operate under certain conditions in gas-enriched globular clusters. AGN disks could also provide a fertile ground for gas-assisted binary capture and in particular the formation of black-hole and other compact object binaries and the production of gravitational-wave (GW) and other high-energy transients, under the assumption of very thin AGN disks. Large scale gaseous disks might be too thick to enable gas-assisted binary capture and previous estimates of the production of GW-sources could be significantly overestimated, and in any case, sensitive to the specific condition and structure of the disks. In protoplanetary disks, however, while gas-assisted binary capture can produce binary KBOs, dynamical friction by small planetsimals is likely to be more efficient. Overall, we show that gas-assisted binary formation is robust and can contribute significantly to the binary formation rate in many environments. In fact, the gas-assisted binary capture rates are sufficiently high such that they will lead to multicaptures, and the formation of higher multiplicity systems.

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M. Rozner, A. Generozov and H. Perets
Mon, 5 Dec 22
42/63

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