Multi-messenger emission from astrophysical sources hidden in γ-rays

Over the last decade, choked jets have attracted particular attention as potential sources of high-energy cosmic neutrinos. Testing this hypothesis is challenging because of the missing gamma-ray counterpart; hence the identification of other electromagnetic signatures is crucial. Extended H envelopes surrounding collapsing massive stars might choke launched jets. In addition, the same progenitors are expected to produce a shock breakout signal in the ultraviolet (UV) and optical lasting several days. Early UV radiation, in particular, will carry important information about the presence and nature of choked jets. While UV observations of core-collapse supernovae have so far been limited, the full potential of observations in this spectral band will soon be transformed by the ULTRASAT satellite mission with its unprecedented field of view. Here, we investigate the detection prospects of choked jet progenitors by ULTRASAT, in relation to their visibility in the optical band by the currently operating telescope ZTF. We find that ULTRASAT will double the volume of sky currently visible by ZTF for the same emitting sources, enlarging the sample of observed Type II supernovae by ∼ 60%. For optimised multi-messenger detections, the delay between neutrinos produced at the shock breakout (during the jet propagation inside the stellar envelope) and ULTRASAT observations should be of ∼4(5) days, with subsequent follow-up by instruments like ZTF about one week after.