Jets in hydrogen-poor superluminous supernovae: constraints from a comprehensive analysis of radio observations

The energy source powering the extreme optical luminosity of hydrogen-stripped superluminous supernovae(SLSNe-I) is not known, but recent studies have highlighted the case for a central engine. Radio and/or X-ray observations are best placed to track the fastest ejecta and probe the presence of outflows from a central engine. We compile all the published radio observations of SLSNe-I to date and present three new observations of two new SLSNe-I. None were detected. Through modeling the radio emission, we constrain the subparsec environments and possible outflows in SLSNe-I. In this sample, we rule out on-axis collimated relativistic jets of the kind detected ingamma-ray bursts (GRBs). We constrain off-axis jets with opening angles of 5° (30°) to energies ofEk 4 10 erg < ´ 50 (Ek 10 erg < 50 ) in environments shaped by progenitors with mass-loss rates ofM M 10 yr < - - 4 1 ˙ (M M 10 yr < - - 5 1 ˙ ) for all off-axis angles, assuming fiducial values e = 0.1 andB = 0.01. The deepest limits rule out emission of the kind seen in faint uncollimated GRBs (with theexception of GRB 060218) and from relativistic SNe. Finally, for the closest SLSN-I, SN 2017egm, we constrain the energy of an uncollimated nonrelativistic outflow like those observed in normal SNe to Ek 10  48 erg.