Abstract:Nine Type Ia supernovae (SNe Ia) with preexisting Hubble Space Telescope (HST) data on their host galaxies have been close enough (within 25 Mpc) to search for a progenitor (Supplementary Table 1). No progenitor system has been found; only upper limits have been possible 31,8,9,10 . Limits range from M g = −3.9 mag in the case of SN 2004W to M I = −8.3 mag for SN 2003cg 31 . These limits provided only poor constraints; in the case of SN 2006dd and SN 2006mr in NGC 1316, they ruled out normal stars with initia… Show more
“…Therefore, analyzing pre-explosion images at the SN position provides a direct way to put constraints on the nature of the progenitor companion star (e.g., McCully et al 2014;Foley et al 2014). However, no progenitors of normal SNe Ia have yet been directly observed, even for the relatively nearby events, SN 2011fe (Li et al 2011) and SN 2014J (Kelly et al 2014), although the probable progenitor system of a SN Iax SN 2012Z (i.e., SN 2012Z-S1) has been recently discovered .…”
Section: The Pre-explosion Progenitormentioning
confidence: 99%
“…This has been suggested to be evidence that supports the SD scenario because such CSM is generally expected to exist around SN Ia progenitor as the result of mass transfer from the companion star, as well as from WD winds. On the other hand, there is some evidence in favour of the DD scenario, e.g., the nondetection of pre-explosion companion stars in normal SNe Ia (Li et al 2011;Bloom et al 2012), the absence of H/He features in the nebular spectra of SNe Ia (Leonard 2007;Lundqvist et al 2013Lundqvist et al , 2015Shappee, Kochanek & Stanek 2013;Maguire et al 2016), the lack of radio and X-ray emission around peak brightness (Bloom et al 2012;Brown et al 2012;Chomiuk et al 2012;Horesh et al 2012;Margutti et al 2014), and the absence of a sur-viving companion star in SN Ia remnants (Kerzendorf et al 2009;Schaefer & Pagnotta 2012).…”
The nature of the progenitors of Type Ia supernovae (SNe Ia) is not yet fully understood. In the single-degenerate (SD) scenario, the collision of the SN ejecta with its companion star is expected to produce detectable ultraviolet (UV) emission in the first few days after the SN explosion within certain viewing angles. It was recently found that the B − V colour of the nearby SN Ia SN 2012cg at about sixteen days before the maximum B-band brightness was about 0.2 mag bluer than those of other normal SNe Ia, which was reported as the first evidence for excess blue light from the interaction of normal SN Ia ejecta with its companion star. In this work, we compare current observations for SN 2012cg from its pre-explosion phase to the late-time nebular phase with theoretical predictions from binary evolution and population synthesis calculations for a variety of popular progenitor scenarios. We find that a main-sequence donor or a carbon-oxygen white dwarf donor binary system is more likely to be the progenitor of SN 2012cg. However, both scenarios also predict properties which are in contradiction to the observed features of this system. Taking both theoretical and observational uncertainties into account, we suggest that it might be too early to conclude that SN 2012cg was produced from an explosion of a Chandrasekhar-mass white dwarf in the SD scenario. Future observations and improved detailed theoretical modelling are still required to place a more stringent constraint on the progenitor of SN 2012cg.
“…Therefore, analyzing pre-explosion images at the SN position provides a direct way to put constraints on the nature of the progenitor companion star (e.g., McCully et al 2014;Foley et al 2014). However, no progenitors of normal SNe Ia have yet been directly observed, even for the relatively nearby events, SN 2011fe (Li et al 2011) and SN 2014J (Kelly et al 2014), although the probable progenitor system of a SN Iax SN 2012Z (i.e., SN 2012Z-S1) has been recently discovered .…”
Section: The Pre-explosion Progenitormentioning
confidence: 99%
“…This has been suggested to be evidence that supports the SD scenario because such CSM is generally expected to exist around SN Ia progenitor as the result of mass transfer from the companion star, as well as from WD winds. On the other hand, there is some evidence in favour of the DD scenario, e.g., the nondetection of pre-explosion companion stars in normal SNe Ia (Li et al 2011;Bloom et al 2012), the absence of H/He features in the nebular spectra of SNe Ia (Leonard 2007;Lundqvist et al 2013Lundqvist et al , 2015Shappee, Kochanek & Stanek 2013;Maguire et al 2016), the lack of radio and X-ray emission around peak brightness (Bloom et al 2012;Brown et al 2012;Chomiuk et al 2012;Horesh et al 2012;Margutti et al 2014), and the absence of a sur-viving companion star in SN Ia remnants (Kerzendorf et al 2009;Schaefer & Pagnotta 2012).…”
The nature of the progenitors of Type Ia supernovae (SNe Ia) is not yet fully understood. In the single-degenerate (SD) scenario, the collision of the SN ejecta with its companion star is expected to produce detectable ultraviolet (UV) emission in the first few days after the SN explosion within certain viewing angles. It was recently found that the B − V colour of the nearby SN Ia SN 2012cg at about sixteen days before the maximum B-band brightness was about 0.2 mag bluer than those of other normal SNe Ia, which was reported as the first evidence for excess blue light from the interaction of normal SN Ia ejecta with its companion star. In this work, we compare current observations for SN 2012cg from its pre-explosion phase to the late-time nebular phase with theoretical predictions from binary evolution and population synthesis calculations for a variety of popular progenitor scenarios. We find that a main-sequence donor or a carbon-oxygen white dwarf donor binary system is more likely to be the progenitor of SN 2012cg. However, both scenarios also predict properties which are in contradiction to the observed features of this system. Taking both theoretical and observational uncertainties into account, we suggest that it might be too early to conclude that SN 2012cg was produced from an explosion of a Chandrasekhar-mass white dwarf in the SD scenario. Future observations and improved detailed theoretical modelling are still required to place a more stringent constraint on the progenitor of SN 2012cg.
“…However, several studies argue against the possibility of giant companions. For example, using preexplosion archival Hubble Space Telescope (HST) images Li et al (2011) ruled out a luminous giant or supergiant as the companion to SN2011fe, although a sub-giant companion could not be excluded by the data.…”
Context. The progenitors of Type Ia supernovae are usually assumed to be either a single white dwarf accreting from a non-degenerate companion (the single-degenerate channel) or the result of two merging white dwarfs (the double degenerate channel). However, no consensus currently exists as to which progenitor scenario is the correct one, or whether the observed Type Ia supernovae rate is produced by a combination of both channels. Unlike a double degenerate progenitor, a single-degenerate progenitor is expected to emit supersoft X-rays for a prolonged period of time (∼1 Myr) as a result of the burning of accreted matter on the surface of the white dwarf. An argument against the single-degenerate channel as a significant producer of Type Ia supernovae has been the lack of observed supersoft X-ray sources and the lower-than-expected integrated soft X-ray flux from elliptical galaxies. Aims. We wish to determine whether it is possible to obscure the supersoft X-ray emission from a nuclear-burning white dwarf in an accreting single-degenerate binary system. In the case of obscured systems we wish to determine their general observational characteristics. Methods. We examine the emergent X-ray emission from a canonical supersoft X-ray system surrounded by a spherically symmetric configuration of material, assuming a black-body spectrum with T bb = 50 eV and L = 10 38 erg s −1 . The circumbinary material is assumed to be of solar chemical abundances, and we leave the mechanism behind the mass-loss into the circumbinary region unspecified. Results. We find that relatively low circumstellar mass-loss rates,Ṁ = 10 −9 −10 −8 M yr −1 , at binary separations of ∼1 AU or less, will cause significant attenuation of the X-rays from the supersoft X-ray source. These circumstellar mass-loss rates are sufficient to make a canonical supersoft X-ray source in typical external galaxies unobservable in Chandra. Conclusions. If steadily accreting, nuclear-burning white dwarfs are canonical supersoft X-ray sources our analysis suggests that they can be obscured by relatively modest circumbinary mass-loss rates. This may explain the discrepancy of supersoft sources relative to the Type Ia supernova rate inferred from observations if the single-degenerate progenitor scenario contributes significantly to the Type Ia supernova rate. Recycled emissions from obscured systems may be visible in wavebands other than X-rays. It may also explain the lack of observed supersoft sources in symbiotic binary systems.
“…The closeness of SN2011fe has made it possible to obtain the tightest constraints on the supernova and its progenitor system to date in a variety of observational windows. Red giant and helium star companions, symbiotic systems, systems at the origin of optically thick winds or containing recurrent novae are excluded for SN2011fe (Li et al 2011a;Bloom et al 2012;Brown et al 2012;Chomiuk et al 2012), leaving only either DD or a few cases of SD as possible progenitor systems of this supernova.…”
Context. SN2011fe was detected by the Palomar Transient Factory in M101 on August 24, 2011, a few hours after the explosion. From the early optical spectra it was immediately realized that it was a Type Ia supernova, thus making this event the brightest one discovered in the past twenty years. Aims. The distance of the event offered the rare opportunity of performing a detailed observation with the instruments onboard INTEGRAL to detect the γ-ray emission expected from the decay chains of 56 Ni. The observations were performed in two runs, one before and around the optical maximum, aimed to detect the early emission from the decay of 56 Ni, and another after this maximum aimed to detect the emission of 56 Co. Methods. The observations performed with the instruments onboard INTEGRAL (SPI, IBIS/ISGRI, JEMX, and OMC) were analyzed and compared with the existing models of γ-ray emission from this kind of supernova. In this paper, the analysis of the γ-ray emission has been restricted to the first epoch. Results. SPI and IBIS/ISGRI only provide upper limits to the expected emission due to the decay of 56 Ni. These upper limits on the gamma-ray flux are 7.1 × 10 −5 ph/s/cm 2 for the 158 keV line and 2.3 × 10 −4 ph/s/cm 2 for the 812 keV line. These bounds allow rejecting at the 2σ level explosions involving a massive white dwarf, ∼1 M in the sub-Chandrasekhar scenario and specifically all models that would have substantial amounts of radioactive 56 Ni in the outer layers of the exploding star responsible for the SN2011fe event. The optical light curve obtained with the OMC camera also suggests that SN2011fe was the outcome of the explosion of a CO white dwarf, possibly through the delayed detonation mode, although other ones are possible, of a CO that synthesized ∼0.55 M of 56 Ni. For this specific model, INTEGRAL would have only been able to detect this early γ-ray emission if the supernova had occurred at a distance < ∼ 2 Mpc. Conclusions. The detection of the early γ-ray emission of 56 Ni is difficult, and it can only be achieved with INTEGRAL if the distance of the event is close enough. The exact distance depends on the specific SNIa subtype. The broadness and rapid rise of the lines are probably at the origin of this difficulty.
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