We present extensive multiwavelength ( radio to X-ray ) observations of the Type Ib/c SN 2013ge from - 13 to + 457 days relative to maximum light , including a series of optical spectra and Swift UV-optical photometry beginning 2 - 4 days post-explosion .
This data set makes SN 2013ge one of the best observed normal Type Ib/c SN at early times—when the light curve is particularly sensitive to the progenitor configuration and mixing of radioactive elements—and reveals two distinct light curve components in the UV bands .
The first component rises over 4 - 5 days and is visible for the first week post-explosion .
Spectra of the first component have blue continua and show a plethora of moderately high-velocity ( \sim 15,000 km s ^ { -1 } ) but narrow ( \sim 3500 km s ^ { -1 } ) spectroscopic features , indicating that the line-forming region is restricted .
The explosion parameters estimated for the bulk explosion ( M _ { ej } \sim 2 - 3 M _ { \odot } ; E _ { K } \sim 1 - 2 \times 10 ^ { 51 } erg ) are standard for Type Ib/c SN , and there is evidence for weak He features at early times—in an object which would have otherwise been classified as Type Ic .
In addition , SN 2013ge exploded in a low metallicity environment ( \sim 0.5 Z _ { \odot } ) and we have obtained some of the deepest radio and X-ray limits for a Type Ib/c SN to date , which constrain the progenitor mass-loss rate to be \dot { M } < 4 \times 10 ^ { -6 } M _ { \odot } yr ^ { -1 } .
We are left with two distinct progenitor scenarios for SN 2013ge , depending on our interpretation of the early emission .
If the first component is cooling envelope emission , then the progenitor of SN 2013ge either possessed an extended ( \gtrsim 30 R _ { \odot } ) envelope or ejected a portion of its envelope in the final \lesssim 1 year before core-collapse .
Alternatively , if the first component is due to outwardly mixed ^ { 56 } Ni , then our observations are consistent with the asymmetric ejection of a distinct clump of nickel-rich material at high velocities .
Current models for the collision of a SN shock with a binary companion can not reproduce both the timescale and luminosity of the early emission in SN 2013ge .
Finally , the spectra of the first component of SN 2013ge are similar to those of the rapidly-declining SN 2002bj .