SN 1993J Research Articles

The radial distribution of radio emission from SN 1993J: Magnetic field amplification due to the Rayleigh-Taylor instability

The radial distribution of radio emission from SN 1993J: Magnetic field amplification due to the Rayleigh-Taylor instability

Testing a stochastic acceleration model of pulsar wind nebulae: early evolution of a wind nebula associated with SN 1986J

ABSTRACT Over 3000 pulsars have been discovered, but none have been confirmed to be younger than a few hundred years. Observing a pulsar after a supernova explosion will help us understand the properties of newborn ones, including their capability to produce gamma-ray bursts and fast radio bursts. Here, the possible youngest pulsar wind nebula (PWN) at the centre of the SN 1986J remnant is studied. We demonstrate that the 5 GHz flux of ‘PWN 1986J’, increasing with time, is consistent with a stochastic acceleration model of PWNe developed to explain the flat radio spectrum of the Crab Nebula. We obtain an acceleration time-scale of electrons/positrons and a decay time-scale of the turbulence responsible for the stochastic acceleration as about 10 yr and 70 yr, respectively. Our findings suggest that efficient stochastic acceleration and rising radio/submm light curves are characteristic signatures of the youngest PWNe. Follow-up ALMA observations of decades-old supernovae within a few tens of Mpc, including SN 1986J, are encouraged to reveal the origin of the flat radio spectrum of PWNe.

Millimeter Observations of the Type II SN 2023ixf: Constraints on the Proximate Circumstellar Medium

We present 1.3 mm (230 GHz) observations of the recent and nearby Type II supernova, SN 2023ixf, obtained with the Submillimeter Array (SMA) at 2.6–18.6 days after explosion. The observations were obtained as part the SMA Large Program, POETS (Pursuit of Extragalactic Transients with the SMA). We do not detect any emission at the location of SN 2023ixf, with the deepest limits of L ν (230 GHz) ≲ 8.6 × 1025 erg s−1 Hz−1 at 2.7 and 7.7 days, and L ν (230 GHz) ≲ 3.4 × 1025 erg s−1 Hz−1 at 18.6 days. These limits are about a factor of 2 times dimmer than the millimeter emission from SN 2011dh (IIb), about 1 order of magnitude dimmer compared to SN 1993J (IIb) and SN 2018ivc (IIL), and about 30 times dimmer than the most luminous nonrelativistic SNe in the millimeter band (Type IIb/Ib/Ic). Using these limits in the context of analytical models that include synchrotron self-absorption and free–free absorption, we place constraints on the proximate circumstellar medium around the progenitor star, to a scale of ∼2 × 1015 cm, excluding the range M ⊙ yr−1 (for a wind velocity, v w = 115 km s−1, and ejecta velocity, v ej ∼ (1 − 2) × 104 km s−1). These results are consistent with an inference of the mass-loss rate based on optical spectroscopy (∼2 × 10−2 M ⊙ yr−1 for v w = 115 km s−1), but are in tension with the inference from hard X-rays (∼7 × 10−4 M ⊙ yr−1 for v w = 115 km s−1). This tension may be alleviated by a nonhomogeneous and confined CSM, consistent with results from high-resolution optical spectroscopy.

A Multiwavelength View of the Rapidly Evolving SN 2018ivc: An Analog of SN IIb 1993J but Powered Primarily by Circumstellar Interaction

SN 2018ivc is an unusual Type II supernova (SN II). It is a variant of SNe IIL, which might represent a transitional case between SNe IIP with a massive H-rich envelope and SNe IIb with only a small amount of the H-rich envelope. However, SN 2018ivc shows an optical light-curve evolution more complicated than that of canonical SNe IIL. In this paper, we present the results of prompt follow-up observations of SN 2018ivc with the Atacama Large Millimeter/submillimeter Array. Its synchrotron emission is similar to that of SN IIb 1993J, suggesting that it is intrinsically an SN IIb–like explosion of an He star with a modest (∼0.5–1M ⊙) extended H-rich envelope. Its radio, optical, and X-ray light curves are explained primarily by the interaction between the SN ejecta and the circumstellar material (CSM); we thus suggest that it is a rare example (and the first involving the “canonical” SN IIb ejecta) for which the multiwavelength emission is powered mainly by the SN–CSM interaction. The inner CSM density, reflecting the progenitor activity in the final decade, is comparable to that of SN IIb 2013cu, which shows a flash spectral feature. The outer CSM density, and therefore the mass-loss rate in the final ∼200 yr, is higher than that of SN 1993J by a factor of ∼5. We suggest that SN 2018ivc represents a missing link between SNe IIP and SNe IIb/Ib/Ic in the binary evolution scenario.

The late-time light curves of Type Ia supernovae: confronting models with observations

ABSTRACT Type Ia supernovae (SNe Ia) play a crucial role as standardizable candles in measurements of the Hubble constant and dark energy. Increasing evidence points towards multiple possible explosion channels as the origin of normal SNe Ia, with possible systematic effects on the determination of cosmological parameters. We present, for the first time, a comprehensive comparison of publicly available SN Ia model nucleosynthetic data with observations of late-time light curve observations of SN Ia events. These models span a wide range of white dwarf (WD) progenitor masses, metallicities, explosion channels, and numerical methodologies. We focus on the influence of 57Ni and its isobaric decay product 57Co in powering the late-time (t > 1000 d) light curves of SNe Ia. 57Ni and 57Co are neutron-rich relative to the more abundant radioisotope 56Ni, and are consequently a sensitive probe of neutronization at the higher densities of near-Chandrashekhar (near-MCh) progenitor WDs. We demonstrate that observations of one SN Ia event, SN 2015F is only consistent with a sub-Chandrasekhar (sub-MCh) WD progenitor. Observations of four other events (SN 2011fe, SN 2012cg, SN 2014J, and SN2013aa) are consistent with both near-MCh and sub-MCh progenitors. Continued observations of late-time light curves of nearby SNe Ia will provide crucial information on the nature of the SN Ia progenitors.

The Effects of Circumstellar Dust Scattering on the Light Curves and Polarizations of Type Ia Supernovae* *Supported by the National Natural Science Foundation of China.

Observational signatures of the circumstellar material (CSM) around Type Ia supernovae (SNe Ia) provide a unique perspective on their progenitor systems. The pre-supernova evolution of the SN progenitors may naturally eject CSM in most of the popular scenarios of SN Ia explosions. In this study, we investigate the influence of dust scattering on the light curves and polarizations of SNe Ia. A Monte Carlo method is constructed to numerically solve the process of radiative transfer through the CSM. Three types of geometric distributions of the CSM are considered: spherical shell, axisymmetric disk, and axisymmetric shell. We show that both the distance of the dust from the SN and the geometric distribution of the dust affect the light curve and color evolutions of SN. We found that the geometric location of the hypothetical circumstellar dust may not be reliably constrained based on photometric data alone, even for the best observed cases such as SN 2006X and SN 2014J, due to the degeneracy of CSM parameters. Our model results show that a time sequence of broadband polarimetry with appropriate time coverage from a month to about one year after explosion can provide unambiguous limits on the presence of circumstellar dust around SNe Ia.

Deriving Thermonuclear Supernova Properties from Gamma-Ray Line Measurements

We illustrate methods for deriving properties of thermonuclear, or Type Ia, supernovae, including synthesized 56Ni mass, total ejecta mass, ejecta kinetic energy, and 56Ni distribution in velocity, from gamma-ray line observations. We simulate data from a small number of published SNe Ia models for a simple gamma-ray instrument, and measure their underlying properties from straightforward analyses. Assuming spherical symmetry and homologous expansion, we calculate exact line profiles for all 56Co and 56Ni lines at all times, requiring only the variation of mass density and 56Ni mass fraction with expansion velocity as input. By parameterizing these quantities, we iterate the parameters to fit the simulated data. We fit the full profiles of multiple lines, or we integrate over the lines and fit line fluxes only versus time. Line profile fits are more robust, but in either case, we can recover accurately the values of the aforementioned properties of the models simulated, given sufficient signal to noise in the lines. A future gamma-ray mission with line sensitivity approaching 10−6 photons cm−2 s−1 would measure these properties for many SNe Ia, and with unprecedented precision and accuracy for a few per year. Our analyses applied to the reported 56Co lines from SN 2014J favor a low 56Ni mass and low ejecta mass, relative to other estimates.

Evolution Toward the Observational Features of a Stripped Envelope Type IIb Supernova in a Binary System

Type IIb supernovae (SNe IIb) that have a thin layer of hydrogen left in their outer envelope have been believed to belong to core collapse supernovae. Mass transfer via Roche lobe overflow can significantly change the nucleosynthesis and surface chemical elements of the progenitors of SNe IIb. We aim to explore what conditions a close binary can meet with the observational features of SNe IIb. We find that an observed low mass SN IIb cannot be produced by a low mass isolated star with M < 20 M ⊙ due to the existence of a thick hydrogen envelope regardless of rotation. Binaries dominate as progenitors in the mass interval (i.e., M < 20 M ⊙) considered in this paper. The 16 M ⊙ primary with a 14 M ⊙ companion in a binary system with ∼10 days < P orb < 720 days can reproduce observational features of SNe IIb (i.e., T eff, , M He, M H, etc.). With the decrease of the hydrogen-rich envelope mass, the radius of the progenitor shrinks. The associated types of SN IIb progenitors from RSGs and YSGs to BSGs are closely related to the amount of hydrogen left in the envelopes. Rotation can bring the production of the CNO reaction to the stellar surface at an early phase, which would explain the nitrogen-rich circumstellar material of SN 1993J and can also explain the large He/H ratio of supernova ejecta. Rotation can increase the corresponding region of the orbital period which can produce an SN IIb.

The Late-Time Light Curves of Type Ia Supernovae: Confronting Models with Observations

Type Ia supernovae (SNe Ia) play a crucial role as standardizable candles in measurements of the Hubble constant and dark energy. Increasing evidence points towards multiple possible explosion channels as the origin of normal SNe Ia, with possible systematic effects on the determination of cosmological parameters. We present, for the first time, a comprehensive comparison of publicly-available SN Ia model nucleosynthetic data with observations of late-time light curve observations of SN Ia events. These models span a wide range of white dwarf (WD) progenitor masses, metallicities, explosion channels, and numerical methodologies. We focus on the influence of $^{57}$Ni and its isobaric decay product $^{57}$Co in powering the late-time ($t > 1000$ d) light curves of SNe Ia. $^{57}$Ni and $^{57}$Co are neutron-rich relative to the more abundant radioisotope $^{56}$Ni, and are consequently a sensitive probe of neutronization at the higher densities of near-Chandrashekhar (near-$M_{\rm Ch}$) progenitor WDs. We demonstrate that observations of one SN Ia event, SN 2015F is only consistent with a sub-$M_{\rm Ch}$ WD progenitor. Observations of four other events (SN 2011fe, SN 2012cg, SN 2014J, SN2013aa) are consistent with both near-$M_{\rm Ch}$ and sub-$M_{\rm Ch}$ progenitors. Continued observations of late-time light curves of nearby SNe Ia will provide crucial information on the nature of the SN Ia progenitors.

Rescued from oblivion: detailed analysis of archival Spitzer data of SN 1993J

ABSTRACT We present an extensive analysis of the late-time mid-infrared (mid-IR) evolution of the Type IIb SN 1993J from 10–26 yr post-explosion based on archival – mostly previously unpublished – photometric data from the Spitzer Space Telescope in conjunction with an archival InfraRed Spectrograph spectrum. SN 1993J is one of the best-studied supernovae (SNe) with an extensive decade-long multiwavelength data set published in various papers; however, its detailed late-time mid-IR analysis is still missing from the literature. Mid-IR data follow not just the continuously cooling SN ejecta but also late-time dust-formation and circumstellar-interaction processes. We provide evidence that the observed late-time mid-IR excess of SN 1993J can be described by the presence of two-component local dust with a dust mass of ∼(3.5–6.0) × 10−3 M⊙ in the case of a partly silicate-based dust composition. The source of these components could be either newly formed dust grains or heating of pre-existing dust via ongoing circumstellar matter interaction also detected at other wavelengths. If it is newly formed, the dust is assumed to be located both in the unshocked inner ejecta and in the outer cold dense shell, just as in the Cassiopeia A remnant and also assumed in other dust-forming SNe a few years after explosion.

SN 2013ai: A Link between Hydrogen-rich and Hydrogen-poor Core-collapse Supernovae

Abstract We present a study of the optical and near-infrared (NIR) spectra of SN 2013ai along with its light curves. These data range from discovery until 380 days after explosion. SN 2013ai is a fast declining Type II supernova (SN II) with an unusually long rise time, 18.9 ± 2.7 days in the V-band, and a bright V-band peak absolute magnitude of −18.7 ± 0.06 mag. The spectra are dominated by hydrogen features in the optical and NIR. The spectral features of SN 2013ai are unique in their expansion velocities, which, when compared to large samples of SNe II, are more than 1,000 km s−1 faster at 50 days past explosion. In addition, the long rise time of the light curve more closely resembles SNe IIb rather than SNe II. If SN 2013ai is coeval with a nearby compact cluster, we infer a progenitor zero-age main-sequence mass of ∼17 M ⊙. After performing light-curve modeling, we find that SN 2013ai could be the result of the explosion of a star with little hydrogen mass, a large amount of synthesized 56Ni, 0.3–0.4 M ⊙, and an explosion energy of 2.5–3.0 × 1051 erg. The density structure and expansion velocities of SN 2013ai are similar to those of the prototypical SN IIb, SN 1993J. However, SN 2013ai shows no strong helium features in the optical, likely due to the presence of a dense core that prevents the majority of γ-rays from escaping to excite helium. Our analysis suggests that SN 2013ai could be a link between SNe II and stripped-envelope SNe.

Exploration of Aspherical Ejecta Properties in Type Ia Supernovae: Progenitor Dependence and Applications to Progenitor Classification

Abstract Several explosions of type Ia supernovae (SNe Ia) have been found to exhibit deviations from spherical symmetry upon closer inspection. Examples are the gamma-ray lines from SN 2014J as measured by INTEGRAL/SPI and morphology information from radioactive isotopes in older remnants such as Tycho. A systematic study of the effects of parameters such as ignition geometry and burning morphology in SNe Ia is still missing. We use a two-dimensional hydrodynamics code with postprocessing nucleosynthesis and simulate the double detonations in a sub-Chandrasekhar-mass carbon–oxygen white dwarf starting from the nuclear runaway in the accumulated He envelope toward disruption of the white dwarf. We explore potential variety through four triggering scenarios that sample main asymmetry drivers. We further investigate their global effects on the aspherical structure of the ejecta based on individual elements. We apply the results to the well-observed SN 2014J and other recently observed SN remnants in order to illustrate how these new observational data, together with other observed quantities, help to constrain the explosion and progenitors of SNe Ia.

Relativistic Motion with Viscosity. I Newton’s Law of Resistance

The equation of motion for a relativistic neutral particle that moves in a medium characterized by a friction proportional to the square of the velocity is analyzed. The relativistic trajectory is derived in a numerical way and in the form of a Taylor series. The astrophysical applications cover the trajectory of SN 1993J and the light curve of gamma ray bursts.

Synthesis of radioactive elements in novae and supernovae and their use as a diagnostic tool

Novae and supernovae play a key role in many fields of Astrophysics and Cosmology. Despite their importance, an accurate description of which objects explode and why and how they explode is still lacking. One of the main characteristics of such explosions is that they are the main suppliers of newly synthesized chemical elements in the Galaxy. Since some of these isotopes are radioactive, it is possible to use the corresponding gamma-rays as a diagnostic tool of the explosion thanks to their independence on the thermal state of the debris. The drawback is the poor sensitivity of detectors in the MeV energy domain. As a consequence, the radioactive lines have only been detected in one core collapse supernova (SN 1987A), one Type Ia supernova (SN 2014J), and one supernova remnant (Cas A). Nevertheless these observations have provided and are providing important information about the explosion mechanisms. Unfortunately, novae are still eluding detection. These results emphasize the necessity to place as soon as possible a new instrument in orbit with enough sensitivity to noticeably enlarge the sample of detected events.

Supernova Interaction with a Dense Detached Shell in SN 2001em

Abstract We carry out a comprehensive analysis of supernova SN 2001em covering a period of 19 yr since discovery. SN 2001em is the oldest supernova known to have undergone a metamorphosis from a stripped envelope to an interacting supernova. An early spectrum indicates it exploded as a Type Ib supernova. Later, the ejecta caught up with a dense circumstellar H-shell, ejected a few thousand years before the explosion, triggering interaction between the supernova ejecta and the dense shell, producing radio, X-ray, and Hα emission. We use archival data with the Very Large Array in radio bands and with Chandra, XMM-Newton, and Swift-XRT in X-ray bands, along with published Hα measurements. We combine these data with our low radio frequency observations with the Giant Metrewave Radio Telescope at two epochs covering three frequencies. While the observations missed the phase when the shock entered the dense shell, the X-rays indicate that the shock came out of the dense shell at around 1750 days. The data suggest a forward shock origin of the X-ray emission. Radio data show a spectral inversion at late epochs ( days) at around 3 GHz, which mimics the properties of the central absorbed component seen in SN 1986J. A possible explanation for this component is that the progenitor of SN 2001em was a massive binary system that had undergone a period of common-envelope evolution. The hydrogen envelope from the SN 2001em progenitor may have been lost as a result of binary interaction.

Would SN1993J Have Been Detected by Next-generation Cerenkov Instruments?

Abstract Already in the first days after the explosion of a supernova, the strong shock expanding forward into the dense wind of the progenitor star can theoretically accelerate particles up to the ∼PeV (=1015 eV) range. These accelerated particles, interacting with the dense wind material, should lead to the production of gamma-rays in the 1–100 TeV range, through pion production. However, no supernova has yet been detected by current Cerenkov instruments, and the question of the detectability of extragalactic supernovae in nearby galaxies (within a few Mpc) by next generation instruments is still open. The detection in the TeV range is especially hindered by the two-photon annihilation process, in which high-energy gamma-rays interact with soft photons from the photosphere to produce electron/positron pairs, thereby degrading the gamma-ray signal from the system. We calculate the temporal evolution of the expected gamma-ray attenuation in the well-studied type IIb SN 1993J, accounting for both temporal and geometrical effects.

Time-dependent high-energy gamma-ray signal from accelerated particles in core-collapse supernovae: the case of SN 1993J

ABSTRACT Some core-collapse supernovae are likely to be efficient cosmic ray accelerators up to the PeV range, and therefore, to potentially play an important role in the overall Galactic cosmic ray population. The TeV gamma-ray domain can be used to study particle acceleration in the multi-TeV and PeV range. This motivates the study of the detectability of such supernovae by current and future gamma-ray facilities. The gamma-ray emission of core-collapse supernovae strongly depends on the level of the two-photon annihilation process: high-energy gamma-ray photons emitted at the expanding shock wave following the supernova explosion can interact with soft photons from the supernova photosphere through the pair production channel, thereby strongly suppressing the flux of gamma-rays leaving the system. In the case of SN 1993J, whose photospheric and shock-related parameters are well measured, we calculate the temporal evolution of the expected gamma-ray attenuation by accounting for the temporal and geometrical effects. We find the attenuation to be of about 10 orders of magnitude in the first few days after the supernova explosion. The probability of detection of a supernova similar to SN 1993J with the Cherenkov Telescope Array is highest if observations are performed either earlier than 1 d, or later than 10 d after the explosion, when the gamma-ray attenuation decreases to about two orders of magnitude.

The intermediate nebular phase of SN 2014J: onset of clumping as the source of recombination

ABSTRACT At the age of about 1 yr, the spectra of most Type Ia supernovae (SNe Ia) are dominated by strong forbidden nebular emission lines of Fe ii and Fe iii. Later observations (at about 2 yr) of the nearby SN 2011fe showed an unexpected shift of ionization to Fe i and Fe ii. Spectra of the very nearby SN Ia 2014J at an intermediate phase (1–1.5 yr) that are presented here show a progressive decline of Fe iii emission, while Fe i is not yet strong. The decrease in ionization can be explained if the degree of clumping in the ejecta increases significantly at ∼1.5 yr, at least in the Fe-dominated zone. Models suggest that clumps remain coherent after about one year, behaving like shrapnel. The high density in the clumps, combined with the decreasing heating rate, would then cause recombination. These data may witness the phase of transition from relatively smooth ejecta to the very clumpy morphology that is typical of SN remnants. The origin of the increased clumping may be the development of local magnetic fields.

The shape of SN 1993J re-analysed

ABSTRACT SN 1993J is one of the best-studied Type IIb supernovae. Spectropolarimetric data analyses were published over two decades ago at a time when the field of supernova spectropolarimetry was in its infancy. Here, we present a new analysis of the spectropolarimetric data of SN 1993J and an improved estimate of its interstellar polarization (ISP) as well as a critical review of ISP removal techniques employed in the field. The polarization of SN 1993J is found to show significant alignment on the q − u plane, suggesting the presence of a dominant axis and therefore of continuum polarization. We also see strong line polarization features, including H β, He i λ5876, H α, He i λ6678, He i λ7065, and high velocity (HV) components of He i λ5876 and H α. SN 1993J is therefore the second example of a stripped-envelope supernova, alongside iPTF13bvn, with prominent HV helium polarization features, and the first to show a likely HV H α contribution. Overall, we determine that the observed features can be interpreted as the superposition of anisotropically distributed line forming regions over ellipsoidal ejecta. We cannot exclude the possibility of an off-axis energy source within the ejecta. These data demonstrate the rich structures that are inaccessible if solely considering the flux spectra but can be probed by spectropolarimetric observations. In future studies, the new ISP corrected data can be used in conjunction with 3D radiative transfer models to better map the geometry of the ejecta of SN 1993J.

Explosive Nucleosynthesis in Sub-Chandrasekhar-mass White Dwarf Models for Type Ia Supernovae: Dependence on Model Parameters

Abstract Recent observations of Type Ia supernovae (SNe Ia) have shown diversified properties of the explosion strength, light curves, and chemical composition. To investigate possible origins of such diversities in SNe Ia, we have presented multidimensional hydrodynamical studies of explosions and associated nucleosynthesis in near-Chandrasekhar-mass carbon–oxygen (CO) white dwarfs (WDs) for a wide range of parameters. In the present paper, we extend our wide parameter survey of models to the explosions of sub-Chandrasekhar-mass CO WDs. We take the double-detonation model for the explosion mechanism. The model parameters of the survey include a metallicity of Z = 0–5 Z ⊙, a CO WD mass of M = 0.90–1.20 M ⊙, and a He envelope mass of M He = 0.05–0.20 M ⊙. We also study how the initial He detonation configuration, such as spherical, bubble, and ring shapes, triggers the C detonation. For these parameters, we derive the minimum He envelope mass necessary to trigger the C detonation. We then examine how the explosion dynamics and associated nucleosynthesis depend on these parameters, and we compare our results with the previous representative models. We compare our nucleosynthesis yields with the unusual abundance patterns of Fe-peak elements and isotopes observed in SNe Ia SN 2011fe, SN 2012cg, and SN 2014J, as well as SN Ia remnant 3C 397, to provide constraints on their progenitors and environments. We provide the nucleosynthesis yields table of the sub-Chandrasekhar-mass explosions, to discuss their roles in the galactic chemical evolution and archaeology.