No Arabic abstract
Many young, massive stars are found in close binaries. Using population synthesis simulations we predict the likelihood of a companion star being present when these massive stars end their lives as core-collapse supernovae (SNe). We focus on stripped-envelope SNe, whose progenitors have lost their outer hydrogen and possibly helium layers before explosion. We use these results to interpret new Hubble Space Telescope observations of the site of the broad-lined Type Ic SN 2002ap, 14 years post-explosion. For a subsolar metallicity consistent with SN 2002ap, we expect a main-sequence companion present in about two thirds of all stripped-envelope SNe and a compact companion (likely a stripped helium star or a white dwarf/neutron star/black hole) in about 5% of cases. About a quarter of progenitors are single at explosion (originating from initially single stars, mergers or disrupted systems). All the latter scenarios require a massive progenitor, inconsistent with earlier studies of SN 2002ap. Our new, deeper upper limits exclude the presence of a main-sequence companion star $>8$-$10$ Msun, ruling out about 40% of all stripped-envelope SN channels. The most likely scenario for SN 2002ap includes nonconservative binary interaction of a primary star initially $lesssim 23$ Msun. Although unlikely ($<$1% of the scenarios), we also discuss the possibility of an exotic reverse merger channel for broad-lined Type Ic events. Finally, we explore how our results depend on the metallicity and the model assumptions and discuss how additional searches for companions can constrain the physics that governs the evolution of SN progenitors.
We present the first systematic investigation of spectral properties of 17 Type Ic Supernovae (SNe Ic), 10 broad-lined SNe Ic (SNe Ic-bl) without observed Gamma-Ray Bursts (GRBs) and 11 SNe Ic-bl with GRBs (SN-GRBs) as a function of time in order to probe their explosion conditions and progenitors. We analyze a total of 407 spectra, which were drawn from published spectra of individual SNe as well as from the densely time-sampled spectra data of Modjaz et al. (2014). In order to quantify the diversity of the SN spectra as a function of SN subtype, we construct average spectra of SNe Ic, SNe Ic-bl without GRBs and SNe Ic-bl with GRBs. We find that SN 1994I is not a typical SN Ic, in contrast to common belief, while the spectra of SN 1998bw/GRB 980425 are representative of mean spectra of SNe Ic-bl. We measure the ejecta absorption and width velocities using a new method described here and find that SNe Ic-bl with GRBs, on average, have quantifiably higher absorption velocities, as well as broader line widths than SNe without observed GRBs. In addition, we search for correlations between SN-GRB spectral properties and the energies of their accompanying GRBs. Finally, we show that the absence of clear He lines in optical spectra of SNe Ic-bl, and in particular of SN-GRBs, is not due to them being too smeared out due to the high velocities present in the ejecta. This implies that the progenitor stars of SN-GRBs are probably He-free, in addition to being H-free, which puts strong constraints on the stellar evolutionary paths needed to produce such SN-GRB progenitors at the observed low metallicities.
We present the photometric and spectroscopic studies of a Type Ib SN 2015ap and a Type Ic SN 2016P. SN 2015ap is one of the bright (M$_{V}$ = $-$18.04 mag) Type Ib while SN 2016P lies at an average value among the Type Ic SNe (M$_{V}$ = $-$17.53 mag). Bolometric light curve modelling of SNe 2015ap and 2016P indicates that both the SNe are powered by $^{56}$Ni + magnetar model with $^{56}$Ni masses of 0.01 M$_{odot}$ and 0.002 M$_{odot}$, ejecta masses of 3.75 M$_{odot}$ and 4.66 M$_{odot}$, spin period P$_{0}$ of 25.8 ms and 36.5 ms and magnetic field B$_{p}$ of 28.39 $times$ 10$^{14}$ Gauss and 35.3 $times$ 10$^{14}$ Gauss respectively. The early spectra of SN 2015ap shows prominent lines of He with a W feature due to Fe complexes while other lines of Mg II, Na I and Si II are present in both SNe 2015ap and 2016P. Nebular phase [O I] profile indicates an asymmetric profile in SN 2015ap. The [O I]/[Ca II] ratio and nebular spectral modelling of SN 2015ap hints towards a progenitor mass between 12 $-$ 20 M$_{odot}$.
The results of a world-wide coordinated observational campaign on the broad-lined Type Ic SN 2003jd are presented. In total, 74 photometric data points and 26 spectra were collected using 11 different telescopes. SN 2003jd is one of the most luminous SN Ic ever observed. A comparison with other Type Ic supernovae (SNe Ic) confirms that SN 2003jd represents an intermediate case between broad-line events (2002ap, 2006aj), and highly energetic SNe (1997ef, 1998bw, 2003dh, 2003lw), with an ejected mass of M_{ej} = 3.0 +/- 1 Mo and a kinetic energy of E_{k}(tot) = 7_{-2}^{+3} 10^{51} erg. SN 2003jd is similar to SN 1998bw in terms of overall luminosity, but it is closer to SNe 2006aj and 2002ap in terms of light-curve shape and spectral evolution. The comparison with other SNe Ic, suggests that the V-band light curves of SNe Ic can be partially homogenized by introducing a time stretch factor. Finally, due to the similarity of SN 2003jd to the SN 2006aj/XRF 060218 event, we discuss the possible connection of SN 2003jd with a GRB.
Unlike the ordinary supernovae (SNe) some of which are hydrogen and helium deficient (called Type Ic SNe), broad-lined Type Ic SNe (SNe Ic-bl) are very energetic events, and all SNe coincident with bona fide long duration gamma-ray bursts (LGRBs) are of Type Ic-bl. Understanding the progenitors and the mechanism driving SN Ic-bl explosions vs those of their SNe Ic cousins is key to understanding the SN-GRB relationship and jet production in massive stars. Here we present the largest set of host-galaxy spectra of 28 SNe Ic and 14 SN Ic-bl, all discovered before 2013 by the same untargeted survey, namely the Palomar Transient Factory (PTF). We carefully measure their gas-phase metallicities, stellar masses (M*s) and star-formation rates (SFRs) by taking into account recent progress in the metallicity field and propagating uncertainties correctly. We further re-analyze the hosts of 10 literature SN-GRBs using the same methods and compare them to our PTF SN hosts with the goal of constraining their progenitors from their local environments by conducting a thorough statistical comparison, including upper limits. We find that the metallicities, SFRs and M*s of our PTF SN Ic-bl hosts are statistically comparable to those of SN-GRBs, but significantly lower than those of the PTF SNe Ic. The mass-metallicity relations as defined by the SNe Ic-bl and SN-GRBs are not significantly different from the same relations as defined by the SDSS galaxies, in contrast to claims by earlier works. Our findings point towards low metallicity as a crucial ingredient for SN Ic-bl and SN-GRB production since we are able to break the degeneracy between high SFR and low metallicity. We suggest that the PTF SNe Ic-bl may have produced jets that were choked inside the star or were able break out of the star as unseen low-luminosity or off-axis GRBs.
SN 2017ein is a narrow-lined Type Ic SN that was found to share a location with a point-like source in the face on spiral galaxy NGC 3938 in pre-supernova images, making SN 2017ein the first credible detection of a Type Ic progenitor. Results in the literature suggest this point-like source is likely a massive progenitor of 60-80 M$_{odot}$, depending on if the source is a binary, a single star, or a compact cluster. Using new photometric and spectral data collected for 200 days, including several nebular spectra, we generate a consistent model covering the photospheric and nebular phase using a Monte Carlo radiation transport code. Photospheric phase modelling finds an ejected mass 1.2-2.0 M$_{odot}$ with an $E_mathrm{k}$ of $sim(0.9 pm0.2)times 10^{51}$ erg, with approximately 1 M$_{odot}$ of material below 5000 km s$^{-1}$ found from the nebular spectra. Both photospheric and nebular phase modelling suggests a $^{56}$Ni mass of 0.08-0.1 M$_{odot}$. Modelling the [OI] emission feature in the nebular spectra suggests the innermost ejecta is asymmetric. The modelling results favour a low mass progenitor of to 16-20 M$_{odot}$, which is in disagreement with the pre-supernova derived high mass progenitor. This contradiction is likely due to the pre-supernova source not representing the actual progenitor.