Results from a Systematic Survey of X-Ray Emission from Hydrogen-poor Superluminous SNe

Abstract

We present the results from a sensitive X-ray survey of 26 nearby hydrogen-poor superluminous supernovae (SLSNe-I) with Swift, Chandra, and XMM. This data set constrains the SLSN evolution from a few days until ∼2000 days after explosion, reaching a luminosity limit L x ∼10 40 erg s −1 and revealing the presence of significant X-ray emission possibly associated with PTF 12dam. No SLSN-I is detected above L 10 erg s-, suggesting that the luminous X-ray emission L x ∼10 45 erg s −1 associated with SCP 60F6 is not common among SLSNe-I. We constrain the presence of off-axis gamma-ray burst (GRB) jets, ionization breakouts from magnetar engines and the density in the sub-parsec environments of SLSNe-I through inverse Compton emission. The deepest limits rule out the weakest uncollimated GRB outflows, suggesting that if the similarity of SLSNe-I with GRB/SNe extends to their fastest ejecta, then SLSNe-I are either powered by energetic jets pointed far away from our line of sight (θ>30°), or harbor failed jets that do not successfully break through the stellar envelope. Furthermore, if a magnetar central engine is responsible for the exceptional luminosity of SLSNe-I, our X-ray analysis favors large magnetic fields B 2 10 14 >´G and ejecta masses M M 3 ej > ☉ , in agreement with optical/UV studies. Finally, we constrain the pre-explosion mass-loss rate of stellar progenitors of SLSNe-I. For PTF 12dam we infer M M 2 10 yr 5 1 <´--☉, suggesting that the SN shock interaction with an extended circumstellar medium is unlikely to supply the main source of energy powering the optical transient and that some SLSN-I progenitors end their lives as compact stars surrounded by a low-density medium similar to long GRBs and type Ib/c SNe.

SN 2010kd: Photometric and Spectroscopic Analysis of a Slow-decaying Superluminous Supernova

“…We converted unabsorbed flux into the luminosity using luminosity-distance information. We found that the unabsorbed flux and X-ray luminosity of each Obs Id are typically similar to those estimated by Levan et al (2013) and Margutti et al (2018).…”

“…Along with the best-fit bolometric light-curve, the limiting X-ray luminosity ( 0.8 × 10 42 erg s −1 ) calculated using the stacked images obtained from Swift-XRT is also plotted (upper-left panel of Figure 2, black arrow); data reduction is discussed in Appendix .1.3. SN 2010kd is not visible in X-rays even near peak optical brightness, as seen in other XRT-observed SLSNe I except for PTF12dam (which was detected; Margutti et al 2018).…”

Constraints on the Environment and Energetics of the Broad-line Ic SN2014ad from Deep Radio and X-Ray Observations

“…Our limits also point to very low density environments, consistent with previous findings that BL-Ic SNe favor low-density media (e.g., see Fig. 5 from Margutti et al 2018), as was also the case for SN 2002ap (Berger et al 2002) and SN 2010ay (Sanders et al 2012).…”

Observational properties of extreme supernovae

“…Only two SLSNe I, out of roughly 30, show an X-ray signature: the Fast SCP06F6 (Lx ~ 10 45 erg s -1 ) [80] and the Slow PTF12dam (Lx ~ 10 40 erg s -1 ) [81]. The fact that the majority of the X-ray limits lie at 10 40 < Lx (erg s -1 ) < 10 45 [52,80,81] suggests that the X-ray emission associated with SCP06F6 is not common among SLSNe I [81]. The SLSNe I X-ray limits would point toward a magnetar magnetic field and ejecta masses similar to what is derived from light-curve models (3 M ≲ M ≲ 30 M) [ 22, 29, 43, 53, 55, 61, 83], and would disfavour CSM interaction as the main source of energy powering the light-curve [52,81].…”