Presupernova Wind Research Articles

Uncommon SN 2020jfo: ordinary explosion of 8 M⊙ red supergiant with dense wind

ABSTRACT We present the hydrodynamic model of Type IIP SN 2020jfo with the unusually short (∼60 d) light-curve plateau. The model suggests the explosion of ≈8 M⊙ red supergiant that ejected ≈6 M⊙ with the energy of ≈0.8 × 1051 erg. The pre-supernova wind density turns out highest among known SNe IIP. Yet the pre-supernova was not embedded into a very dense confined circumstellar shell that is a feature of some Type IIP supernovae, so the circumstellar interaction in close environment does not contribute noticeably to the initial (∼10 d) bolometric luminosity. Despite uncommon appearance SN 2020jfo turns out similar to SN 1970G in the V-band light curve, photospheric velocities, and, possibly, luminosity as well.

Can pre-supernova winds from massive stars enrich the interstellar medium with nitrogen at high redshift?

AbstractUnderstanding the nucleosynthetic origin of nitrogen and the evolution of the N/O ratio in the interstellar medium is crucial for a comprehensive picture of galaxy chemical evolution at high-redshift because most observational metallicity (O/H) estimates are implicitly dependent on the N/O ratio. The observed N/O at high-redshift shows an overall constancy with O/H, albeit with a large scatter. We show that these heretofore unexplained features can be explained by the pre-supernova wind yields from rotating massive stars (M≳10M⊙,ν/νcrit≳0.4). Our models naturally produce the observed N/O plateau, as well as the scatter at low O/H. We find the scatter to arise from varying star formation efficiency. However, the models that have supernovae dominated yields produce a poor fit to the observed N/O at low O/H. This peculiar abundance pattern at low O/H suggests that dwarf galaxies are most likely to be devoid of SNe yields and are primarily enriched by pre-supernova wind abundances.

New expansion rate measurements of the Crab nebula in radio and optical

We present new radio measurements of the expansion rate of the Crab nebula's synchrotron nebula over a ~30-yr period. We find a convergence date for the radio synchrotron nebula of CE 1255 +- 27. We also re-evaluated the expansion rate of the optical line emitting filaments, and we show that the traditional estimates of their convergence dates are slightly biased. Using an un-biased Bayesian analysis, we find a convergence date for the filaments of CE 1091 +- 34 (~40 yr earlier than previous estimates). Our results show that both the synchrotron nebula and the optical line-emitting filaments have been accelerated since the explosion in CE 1054, but that the synchrotron nebula has been relatively strongly accelerated, while the optical filaments have been only slightly accelerated. The finding that the synchrotron emission expands more rapidly than the filaments supports the picture that the latter are the result of the Rayleigh-Taylor instability at the interface between the pulsar-wind nebula and the surrounding freely-expanding supernova ejecta, and rules out models where the pulsar wind bubble is interacting directly with the pre-supernova wind of the Crab's progenitor.

On the cosmic ray spectrum from type II supernovae expanding in their red giant presupernova wind

While from the energetic point of view supernova remnants are viable sources of Galactic cosmic rays (CRs), the issue of whether they can accelerate protons up to a few PeV remains unsolved. Here we discuss particle acceleration at the forward shock of supernovae, and discuss the possibility that the current of escaping particles may excite a non-resonant instability that in turn leads to the formation of resonant modes that confine particles close to the shock, thereby increasing the maximum energy. This mechanism is at work throughout the expansion of the supernova explosion, from the ejecta dominated (ED) phase to the Sedov–Taylor (ST) phase. The transition from one stage to the other reflects in a break in the spectrum of injected particles. Because of their higher explosion rate, we focus our work on type II SNe expanding in the slow, dense wind, produced by the red super-giant progenitor stars. When the explosion occurs in such winds, the transition between the ED and the ST phase is likely to take place within a few tens of years. The highest energies are reached at even earlier times, when, however, a small fraction of the mass of ejecta has been processed. As a result, the spectrum of accelerated particles shows a break in the slope, at an energy that is the maximum energy (EM) achieved at the beginning of the ST phase. Above this characteristic energy, the spectrum becomes steeper but remains a power law rather than developing an exponential cutoff. An exponential cut is eventually present at much higher energies but it does not have a phenomenological relevance. We show that for parameters typical of type II supernovae, EM for protons can easily reach values in the PeV range, confirming that type II SNRs are the best candidate sources for CRs at the knee.From the point of view of implications of this scenario on the measured particle spectra, we have tried to fit KASCADE-Grande, ARGO -YBJ and YAC1-Tibet Array data with our model but we could not find any combination of the parameters that could explain all data sets. Indeed the recent measurement of the proton and helium spectra in the knee region, with the ARGO-YBJ and YAC1-Tibet Array, has made the situation very confused. These measurements suggest that the knee in the light component is at ∼650TeV, appreciably below the knee in the overall spectrum. On one hand this finding would resolve the problem of reaching very high energies in supernovae, but on the other it would open a critical issue in the transition region between Galactic and extragalactic CRs.

On the cosmic ray spectrum from type II Supernovae expanding in their red giant presupernova wind

While from the energetic point of view SNRs are viable sources of Galactic CRs, the issue of whether they can accelerate protons up to PeV remains unsolved. Here we discuss particle acceleration at the forward shock of SN and discuss the possibility that the escaping particle current may excite a non-resonant instability that in turn leads to the formation of resonant modes confining particles close to the shock and increasing the maximum energy. This mechanism works throughout the expansion of the SN explosion, from the ejecta dominated (ED) to the Sedov-Taylor (ST) phase. Because of their higher explosion rate,we focus on type II SNae expanding in the slow, dense red supergiant wind. When the explosion occurs in such winds, the transition between the ED and the ST phase is likely to take place within a few tens of years. As a result, the spectrum of accelerated particles shows a break in the slope, at the maximum energy (E M ) achieved at the beginning of the ST phase. Above this energy, the spectrum becomes steeper but remains a power law than developing an exponential cutoff. We show that for type II SNae typical parameters, proton E M can easily reach PeV energies, confirming that type II SNRs are the best candidate sources for CRs at the knee. We have tried to fit KASCADE-Grande, ARGO -YBJ and YAC1-Tibet Array data with our model but we could not find any parameter combination that could explain all data sets. Indeed the recent measurement of the proton and helium spectra in the knee region, with the ARGO-YBJ and YAC1-Tibet Array, has made the situation very confused. These measurements suggest that the knee in the light component is at 650 TeV, appreciably below the overall spectrum knee. This finding would resolve the problem of reaching very high energies in SNae, but, on the other hand, it would open a critical issue in the transition region between Galactic and extragalactic CRs.

TYPE IIb SUPERNOVAE WITH COMPACT AND EXTENDED PROGENITORS

The classic example of a Type IIb supernova is SN 1993J, which had a cool extended progenitor surrounded by a dense wind. There is evidence for another category of Type IIb supernova which has a more compact progenitor with a lower density, probably fast, wind. Distinguishing features of the compact category are: weak optical emission from the shock heated envelope at early times; nonexistent or very weak H emission in the late nebular phase; rapidly evolving radio emission; rapid expansion of the radio shell; and expected nonthermal as opposed to thermal X-ray emission. Type IIb supernovae that have one or more of these features include SNe 1996cb, 2001ig, 2003bg, 2008ax, and 2008bo. All of these with sufficient radio data (the last four) show evidence for presupernova wind variability. We estimate a progenitor envelope radius ~1e11 cm for SN 2008ax, a value consistent with a compact Wolf-Rayet progenitor. Supernovae in the SN 1993J extended category include SN 2001gd and probably the Cas A supernova. We suggest that the compact Type IIb events be designated Type cIIb and the extended ones Type eIIb. The H envelope mass dividing these categories is ~0.1 Msun.

Radio monitoring of NGC 7469: late-time radio evolution of SN 2000ft and the circumnuclear starburst in NGC 7469

We present the results of an eight-year long monitoring of the radio emission from the Luminous Infrared Galaxy (LIRG) NGC 7469, using 8.4 GHz Very Large Array (VLA) observations at 0.3'' resolution. Our monitoring shows that the late time evolution of the radio supernova SN 2000ft follows a decline very similar to that displayed at earlier times of its optically thin phase. The late time radio emission of SN 2000ft is therefore still being powered by its interaction with the presupernova stellar wind, and not with the interstellar medium (ISM). Indeed, the ram pressure of the presupernova wind is \rho_w v_w^2 \approx 7.6E-9 dyn/cm^2, at a supernova age of approximately 2127 days, which is significantly larger than the expected pressure of the ISM around SN 2000ft. At this age, the SN shock has reached a distance r_{sh \approx 0.06 pc, and our observations are probing the interaction of the SN with dense material that was ejected by the presupernova star about 5820 years prior to its explosion. From our VLA monitoring, we estimate that the swept-up mass by the supernova shock after about six years of expansion is \approx 0.29 M_sun, assuming an average expansion speed of the supernova of 10000 km/s. We also searched for recently exploded core-collapse supernovae in our VLA images. Apart from SN 2000ft (S_\nu \approx 1760 microJy at its peak, corresponding to 1.1E28 erg/s/Hz, we found no evidence for any other radio supernova (RSN) more luminous than \approx 6.0E26 erg/s/Hz, which suggests that no other Type IIn SN has exploded since 2000 in the circumnuclear starburst of NGC 7469.

Three‐dimensional Model of Broadband Emission from Supernova Remnants Undergoing Nonlinear Diffusive Shock Acceleration

We present a three-dimensional model of supernova remnants (SNRs) in which the hydrodynamical evolution of the remnant is modeled consistently with nonlinear diffusive shock acceleration occurring at the outer blast wave. The model includes particle escape and diffusion outside of the forward shock and particle interactions with arbitrary distributions of external ambient material, such as molecular clouds. We include synchrotron emission and cooling, bremsstrahlung radiation, neutral pion production, and inverse Compton (IC) and Coulomb energy loss. Broadband spectra have been calculated for typical parameters, including dense regions of gas external to a 1000 yr old SNR. In this paper, we describe the details of our model, but do not attempt a detailed fit to any specific remnant. We also do not include magnetic field amplification (MFA), even though this effect may be important in some young remnants. Our aim is to develop a flexible platform that can be generalized to include effects such as MFA, and that can be easily adapted to various SNR environments, including Type Ia SNRs, which explode in a constant-density medium, and Type II SNRs, which explode in a presupernova wind. When applied to a specific SNR, our model will predict cosmic-ray spectra and multiwavelength morphology in projected images for instruments with varying spatial and spectral resolutions. We show examples of these spectra and images and emphasize the importance of measurements in the hard X-ray, GeV, and TeV gamma-ray bands for investigating key ingredients in the acceleration mechanism, and for deducing whether or not TeV emission is produced by IC from electrons or pion decay from protons.

Supernova Reverse Shocks: SiC Growth and Isotopic Composition

We present new mechanisms by which the isotopic compositions of X-type grains of presolar SiC are altered by reverse shocks in Type II supernovae. We address three epochs of reverse shocks: pressure wave from the H envelope near t = 106 s, reverse shock from the presupernova wind near 108-109 s, and reverse shock from the interstellar medium near 1010 s. Using one-dimensional hydrodynamics we show that the first creates a dense shell of Si and C atoms near 106 s in which the SiC surely condenses. The second reverse shock causes precondensed grains to move rapidly forward through decelerated gas of different isotopic composition, during which implantation, sputtering, and further condensation occur simultaneously. The third reverse shock causes only further ion implantation and sputtering, which may affect trace element isotopic compositions. Using a 25 M☉ supernova model we propose solutions to the following unsolved questions: Where does SiC condense? Why does SiC condense in preference to graphite? Why is condensed SiC 28Si-rich? Why is O-richness no obstacle to SiC condensation? How many atoms of each isotope are impacted by a grain that condenses at time t0 at radial coordinate r0? These many considerations are put forward as a road map for interpreting SiC X grains found in meteorites and their meaning for supernova physics.

Cassiopeia A and Its Clumpy Presupernova Wind

The observed shock wave positions and expansion in Cas A can be interpreted in a model of supernova interaction with a freely expanding stellar wind with a mass loss rate of ~3e-5 Msun/yr for a wind velocity of 10 km/s. The wind was probably still being lost at the time of the supernova, which may have been of Type IIn or IIb. The wind may play a role in the formation of very fast knots observed in Cas A. In this model, the quasi-stationary flocculi (QSFs) represent clumps in the wind, with a density contrast of several 1000 compared to the smooth wind. The outer, unshocked clumpy wind is photoionized by radiation from the supernova, and is observed as a patchy HII region around Cas A. This gas has a lower density than the QSFs and is heated by nonradiative shocks driven by the blast wave. Denser clumps have recombined and are observed as HI compact absorption features towards Cas A.

X‐Ray, Optical, and Radio Observations of the Type II Supernovae 1999em and 1998S

Observations of the Type II-P (plateau) supernova SN 1999em and Type IIn (narrow emission line) SN 1998S have enabled estimation of the profile of the SN ejecta, the structure of the circumstellar medium (CSM) established by the pre-SN stellar wind, and the nature of the shock interaction. SN 1999em is the first Type II-P detected at both X-ray and radio wavelengths. It is the least radio luminous and one of the least X-ray luminous SNe ever detected (except for the unusual and very close SN 1987A). The Chandra X-ray data indicate nonradiative interaction of SN ejecta with a power-law density profile (ρ ∝ r-n, with n ~ 7) for a pre-SN wind with a low mass-loss rate of ~2 × 10-6 M☉ yr-1 for a wind velocity of 10 km s-1, in agreement with radio mass-loss rate estimates. The Chandra data show an unexpected, temporary rise in the 0.4-2.0 keV X-ray flux at ~100 days after explosion. SN 1998S, at an age of more than 3 yr, is still bright in X-rays and is increasing in flux density at centimeter radio wavelengths. Spectral fits to the Chandra data show that many heavy elements (Ne, Al, Si, S, Ar, and Fe) are overabundant with respect to solar values. We compare the observed elemental abundances and abundance ratios to theoretical calculations and find that our data are consistent with a progenitor mass of approximately 15-20 M☉ if the heavy-element ejecta are radially mixed out to a high velocity. If the X-ray emission is from the reverse shock wave region, the supernova density profile must be moderately flat at a velocity ~104 km s-1, the shock front is nonradiative at the time of the observations, and the mass-loss rate is (1-2) × 10-4 M☉ yr-1 for a presupernova wind velocity of 10 km s-1. This result is also supported by modeling of the radio emission, which implies that SN 1998S is surrounded by a clumpy or filamentary CSM established by a high mass-loss rate, ~2 × 10-4 M☉ yr-1, from the presupernova star.

The Imprint of Presupernova Evolution on Supernova Remnants

The evolution of Type Ia supernova binary system progenitors is highly uncertain. Several evolutionary models predict that the accretion of mass onto the white dwarf is accompanied by mass ejection from the binary in the form of a powerful wind, but very few observations have been made during the initial phase of formation of supernova remnants, when the interaction of supernova ejecta with presupernova wind could be tested. Here we present hydrodynamical simulations of supernova ejecta interaction with an ambient medium modified by presupernova wind. The structure of the ambient medium when the supernova explodes is very sensitive to the details of wind history, and the evolution of the supernova remnant can be affected during several thousand years. We have found that the forward shock expansion parameter is a good tool for discriminating between several wind models. The evolution of the supernova remnant in the presence of an ambient medium modified by interaction with presupernova wind cannot be described by a similarity solution. We also rule out simple models based on a circumstellar medium that merges smoothly with a uniform density ambient medium.

On Flamsteed's supernova Cas A

The Galactic supernova remnant Cas A is believed to be the result of a recent (∼ 300 yrs) and nearby (D ∼ 3 kpc) explosion of a massive star. The discovery of gamma-ray line emission due to radioactive 44Ti with COMPTEL supports the massive star origin of Cas A. However, the ejection of 44Ti should be accompanied by large amounts of 56Ni and 57Ni, which would have made this a very bright supernova. No 17th century sightings of this event exist, with the notable exception of the ∼ 6th mag star 3 Cas reported by Sir John Flamsteed. This mystery may be solved by assuming that the supernova was enshrouded by a dusty envelope, perhaps provided by a pre-supernova wind. X-ray observations with ROSAT provide evidence for this scenario through the simultaneous analysis of absorption along the line of sight and the extended X-ray scattering halo around Cas A. The supernova shock destroyed the dust, reducing the line-of-sight opacity to a value consistent with a 3 kpc path through an average ISM. ROSAT detects the evaporated dust as excess absorption.

Supernovae in dense winds

An overview of the optical effects caused by a supernova explosion in a dense circumstellar wind is presented. Some unclear points and difficulties of the conventional models are pointed out and additional processes suggested, namely, thermal conductivity between the shocked wind and fragmented shocked ejecta, interaction of the wind with a relativistic precursor, and emission from accelerated fragments of shocked wind clouds. A simple model is proposed for cloud formation in the pre-supernova wind.

The interaction of Crab-like supernova remnants with their surroundings

The interaction of a bubble of relativistic fluid created by pulsar energy input with an ambient meium is studied by means of self-similar solutions. Three possible ambient media are considered: a stationary, uniform medium; a medium created by a slow, steady presupernova wind; and a uniformly expanding medium created by a supernova explosion. The three situations lead to shells of shocked gas with different thicknesses and internal structures. The third case leads to a cooler shell than the other two. The models are applied to the Crab nebula. Current observations do not distinguish betwen the various models, but X-ray, radio, and ooptical observations are proposed which will be helpful in resolving this problem. The solution will indicate whether SN 1054 was an anomalously low-energy event.

Radio and X-ray Emission from Newly Born Remnants

Radio and X-ray observations of SN 1979c and SN 1980k offer a unique opportunity of monitoring the transition from supernovae to remnants. By means of the two-frequency radio light curves, we test the hypothesis that these objects are surrounded by circumstellar matter, originated in a pre supernova wind, and derive the relevant parameters. Then we use the absorption-corrected light curves to test the various proposed models. SN 1980 k appears to be powered by a canonical shock, while SN 1979c is a good plerion candidate. An optical pulsar could still be detected at its location.