Over the past 8 years, Advanced LIGO and Advanced Virgo have detected about 90 gravitational-wave (GW) events, all of them produced by the coalescence of a compact binary system (CBC). In addition to CBCs, new types of GW signals are expected to be observed in the near future, as the sensitivity and observing time of GW detectors increase. Among them, we refer to long-duration transients as GW signals whose duration in the frequency band of the detectors ranges from few seconds to hours. Such signals could be produced by a variety of sources, including newly-born neutron stars, isolated magnetars, or accretion disks around black holes. Because the emission processes at play are not well enough modeled, their detection must rely on search algorithms that make few assumption on the nature of the signal, which gives rise to specific data analysis challenges.

In this seminar I will give an overview of potential sources of long-duration GWs, and explain the data analysis techniques employed to search for these signals in GW detectors' data. I will depict the current status of these searches in the LIGO-Virgo-KAGRA collaboration, as well as detection prospects with 3rd generation detectors such as Einstein Telescope. Finally I will highlight the need for further development in data analysis methods, especially for parameter estimation, that will be required to infer the maximal amount of information on the source once a signal is detected.