A Search for Relativistic Ejecta in a Sample of ZTF Broad-lined Type Ic Supernovae

Abstract

The dividing line between gamma-ray bursts (GRBs) and ordinary stripped-envelope core-collapse supernovae (SNe) is yet to be fully understood. Observationally mapping the variety of ejecta outcomes (ultrarelativistic, mildly relativistic, or nonrelativistic) in SNe of Type Ic with broad lines (Ic-BL) can provide a key test to stellar explosion models. However, this requires large samples of the rare SN Ic-BL events with follow-up observations in the radio, where fast ejecta can be probed largely free of geometry and viewing angle effects. Here, we present the results of a radio (and X-ray) follow-up campaign of 16 SNe Ic-BL detected by the Zwicky Transient Facility (ZTF). Our radio campaign resulted in four counterpart detections and 12 deep upper limits. None of the events in our sample is as relativistic as SN 1998bw and we constrain the fraction of SN 1998bw-like explosions to <19% (3σ Gaussian equivalent), a factor of ≈2 smaller than previously established. We exclude relativistic ejecta with radio luminosity densities in between ≈5 × 1027 erg s−1 Hz−1 and ≈1029 erg s−1 Hz−1 at t ≳ 20 days since explosion for ≈60% of the events in our sample. This shows that SNe Ic-BL similar to the GRB-associated SNe 1998bw, 2003lw, and 2010bh, or to the relativistic SNe 2009bb and iPTF17cw, are rare. Our results also exclude an association of the SNe Ic-BL in our sample with largely off-axis GRBs with energies E ≳ 1050 erg. The parameter space of SN 2006aj-like events (faint and fast-peaking radio emission) is, on the other hand, left largely unconstrained, and systematically exploring it represents a promising line of future research.

Collapsars as Sites of r-process Nucleosynthesis: Systematic Photometric Near-infrared Follow-up of Type Ic-BL Supernovae

“…Our literature sample is described in Section 5. Some of these candidates are part of a companion study (Corsi et al 2023) focusing on the radio properties of SNe Ic-BL; the full ZTF sample of SNe Ic-BL will be presented in G. P. Srinivasaragavan et al (in preparation). For all Swift X-Ray Telescope (XRT) fluxes reported from the companion study, we assume a spectral model of a power-law spectrum with the photon index of Γ = 2 corrected for Galactic absorption only.…”

“…All Swift fluxes have an energy range of 0.3-10 keV. For a more thorough discussion of whether the reported X-ray and radio emission correspond to transient or host-only emission, see Sections 3.4 and 3.5 of Corsi et al (2023).…”

HAFFET: Hybrid Analytic Flux FittEr for Transients

“…As shown, the bolometric correction approach using only two bands provides quite similar bolometric luminosities to those from the blackbody or spectra integration. We estimated the luminosities for ZTF SNe Ic-BL in Corsi et al (2023) and in Anand et al (2023), and for comparison we also test the methods on a few famous SNe, e.g., SN 1998bw, and found consistent results between the different methods. Therefore, we set the Lyman bolometric correction method as the default approach for stripped-envelope SNe and SNe II in HAFFET, and provide functions to convert BVR to gr in case an object is observed in Johnson filters.…”

“…That paper (S. Yang et al 2023, in preparation) contains an analysis of the objects that are used here to demonstrate the capabilities of HAFFET, and is hereafter referred to as Paper I. We have also estimated the luminosities for ZTF SNe Ic-BL using HAFFET in Corsi et al (2023), Srinivasaragavan et al (2023), and Anand et al (2023).…”

Characterizing the Ordinary Broad-line Type Ic SN 2023pel from the Energetic GRB 230812B

“…Finally, we use the associated g − r and g − i colors at every epoch to generate rand i-band LCs. After applying the correct distance modulus and k-corrections to these LCs, we compare them to our observed SN flux using Markov Chain Monte Carlo (MCMC) techniques with the Python package EMCEE (Foreman-Mackey et al 2013) to fit for the nickel mass and the photon diffusion timescale, which have uniform priors corresponding to values derived in the literature (Corsi et al 2016;Taddia et al 2019;Corsi et al 2023). We note that this method (though using an SN 1998bw-like LC instead) was also used to estimate the nickel mass of SN 2022xiw, the SN associated with GRB 221009A, in Srinivasaragavan et al (2023).…”