We present ZTF18aaqjovh ( SN 2018bvw ) , a high-velocity ( “ broad-lined ” ) stripped-envelope ( Type Ic ) supernova ( Ic-BL SN ) discovered in the Zwicky Transient Facility one-day cadence survey .
The shape of the optical light curve and the evolution of the photospheric velocity are most similar to that of the Type Ic-BL SN 1998bw , which was associated with a low-luminosity gamma-ray burst ( LLGRB ) .
However , the radio luminosity of ZTF18aaqjovh is almost two orders of magnitude fainter than that of SN 1998bw at the same velocity phase , and is more similar to that of the Type Ic-BL SN iPTF17cw .
No X-ray emission was detected , setting a limit that is fainter than the X-ray emission from LLGRB-SNe 1998bw , 2010bh , and 2006aj but consistent with the X-ray emission from radio-loud SN 2009bb .
From our radio observations we estimate a shock velocity of v = 0.06 –0.4 c and a mass-loss rate of \dot { M } = 0.1 –3 \times 10 ^ { -4 } ( v _ { \mathrm { wind } } / 1000 \mbox { $ km$ } \mbox { $ s ^ { -1 } $ } ) % \mbox { $ M _ { \odot } $ } \mbox { $ yr ^ { -1 } $ } .
A search of high-energy catalogs reveals no compelling GRB counterpart to ZTF18aaqjovh .
The lack of detection by the interplanetary network sets a limit on the prompt GRB luminosity of L _ { \gamma, \mathrm { iso } } \approx 1.6 \times 10 ^ { 48 } \mbox { $ erg$ } \mbox { $ s% ^ { -1 } $ } , ruling out a classical GRB but not an LLGRB .
ZTF18aaqjovh shares a number of features in common with engine-driven explosions : the high photospheric velocity ( SN 1998bw ) , the associated radio emission ( SN 2006aj , iPTF17cw ) , and the optical light curve ( SN 1998bw ) .
However , the velocity of the radio-emitting ejecta is similar to that seen in interacting SNe with no evidence for an engine .
Therefore , ZTF18aaqjovh represents another transition event between GRB-SNe and “ ordinary ” Ic-BL SNe .