arXiv subjects

Noam Soker

Publications and source records attributed to Noam Soker.

At least 19 recordsLinked to original sources

arXiv2026

One Precessing Jet Pair, Diverse Core-Collapse Supernova Remnant Morphologies

We produce a diverse set of observed core-collapse supernova (CCSN)-type morphologies using a precessing pair of opposite jets within the jittering-jets explosion mechanism (JJEM) framework. We conduct a three-dimensional hydrodynamical simulation of a precessing pair of jets that explode a massive star, and find that a single precessing pair of opposite jets can generate S-shaped structures, pipe-spout-blowout features as observed in the Cygnus Loop, multiple apparent pairs of opposite protrusions similar to some morphological features in S147, and H-shaped structures with a prominent bar, similar to the one observed in the 3C 397 remnant. At small scales, the jets form clumps and filaments, resulting from instabilities and vortices that the jets induce in the ejecta as they interact with the stellar material. We did not aim the simulation to reproduce any particular CCSN remnant, but rather to explore the resulting morphological features. Our finding of simulated features similar to observed ones supports the role of jets in exploding CCSNe and, in turn, supports the claim that the JJEM is the primary explosion mechanism of CCSNe.

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arXiv2026

Stellar black hole binaries from two common envelope evolution phases in triple stellar systems

We propose a triple-star evolutionary channel involving two common envelope evolution (CEE) phases to form close binary black hole (BBH) systems with an average positive effective inspiral spin $χ_{\rm eff}$ and a tail of systems having $χ_{\rm eff}<0$, as observed by gravitational wave detectors. $χ_{\rm eff}$ is the mass-weighted spin of the two merging BHs, and a positive (negative) value indicates an effective spin along (opposite) the orbital angular momentum. The first BH progenitor engulfs a low-mass star during the post-main-sequence evolution. The tertiary star spirals in and spins up the core, which forms the first BH at the first core-collapse supernova (CCSN) explosion. Its spin is along the orbital angular momentum of the inner binary, which can be highly inclined to the outer binary angular momentum. The secondary star later engulfs the BH in a second CEE phase and explodes as a CCSN to form the second BH with a spin that is more aligned with the orbital angular momentum of the two BHs. We use empirically calibrated initial distributions of triple-star systems consisting of two massive stars and impose a hierarchical stability criterion. We compare the predicted ratio of merging BBHs to CCSN explosion rates and find it is up to a factor of 2 larger than the observed rate. This channel can significantly contribute to the population of observed merging BBHs and can explain their qualitative spin distribution.

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arXiv2026

Long-lived intermittent accretion disks in the jittering jets explosion mechanism (JJEM) of core-collapse supernovae

Motivated by observations of core-collapse supernova (CCSN) remnants that suggest cases where one to three energetic pairs of jets dominate the CCSN remnant morphology and, hence, the CCSN explosion energy, I examine the formation of long-lived intermittent accretion disks that launch such pairs of energetic jets in the framework of the jittering-jets explosion mechanism (JJEM). In the JJEM, pairs of jets explode all CCSNe. In most CCSNe, stochastic angular momentum fluctuations in the convective zones of the pre-collapse core seed instabilities above the newly born neutron star that lead to the formation of intermittent accretion disks. These disks launch several to about twenty pairs of jets that explode the star. CCSNRs with signatures of 1-3 very energetic pairs of jets require long-lived, intermittent accretion disks. I quantitatively show that viscosity-driven angular momentum transport in the disk can prolong its lifetime even when material with zero angular momentum continues to feed the disk. Other effects that I do not study here can also prolong the disk lifetime somewhat: jets might prevent matter from accreting from the polar direction, and angular momentum fluctuations can, in some cases, add up to a positive angular momentum. The viscosity mechanism I study here, along with these other effects, can prolong the lifetime of 1-3 intermittent accretion disks (or none), which then launch energetic jet pairs. This study adds to the wide variety of morphologies that the JJEM can explain, somewhat supporting the claim that the JJEM is the primary explosion mechanism of CCSNe.

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arXiv2026

Supernova 1987A was a "failed supernova" twenty thousand years before its jet-driven explosion

I show that the progenitor of supernova (SN) 1987A faded substantially and became red for hundreds of years to observers in and near the plane of the equatorial ring, because the equatorial ring, which was formed by a binary interaction between the SN 1987A progenitor and a main-sequence companion that ejected material about 20,000 years before the explosion, obscured the progenitor. For a few hundred years, the luminosity for such hypothetical observers was mainly light scattered by the two outer rings, which amounted to ~5% of the progenitor luminosity. In present terms, this event would have been classified as a "failed supernova" by these observers, although there was no core collapse, no black hole formation, and nothing failed. Rather, this event was a type II ILOT (intermediate-luminosity optical transient), in which equatorial ejecta temporarily obscured the central source. After a few hundred years, the outer rings became transparent, the inner ring became more transparent, and the SN 1987A progenitor brightened over a few thousand years to its normal luminosity for equatorial observers. This finding strengthens the claim that "failed supernova" candidates are likely to be type II ILOTs. Although the binary interaction also spun up the core, the bipolar morphology of SN 1987A (its Keyhole) is misaligned with the triple-ring system. I use the jittering jets explosion mechanism (JJEM) to speculate on a scenario that might explain this misalignment. This study adds small but unique support to the claim that the JJEM is the primary explosion mechanism of CCSNe.

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arXiv2026

Supernova remnant 0509-67.5 is consistent with an explosion inside an old planetary nebula (SNIP)

I critically examine claims in the paper arXiv:2608.11978 that the double-detonation (DDet) scenario explains the type Ia supernova (SN Ia) remnant (SNR Ia) SNR 0509-67.5, and find the arguments supporting the DDet scenario weak; hence, I reiterate my claim that the core-degenerate (CD) scenario, where a lonely white dwarf (WD), which is the merger product of a lower-mass WD and the core of an asymptotic giant branch star, exploded inside an old planetary nebula, i.e., an SNIP, best explains SNR 0509-67.5. I find that the flat edge of the SNR in the north-northeast, which in the DDet scenario is due to a shadow by the companion to the WD that exploded, is not unique in this SNR, and that the circumstellar matter, i.e., an old planetary nebula, shaped this edge, as well as other structures on the edge of this SNR. I emphasize that analyses of SNRs Ia and SNe Ia at late stages must consider the claim that most normal SNe Ia are SNIPs, implying that old planetary nebulae can heavily shape their morphologies. The bulk velocity inferred from an iron emission line in SNR 0509-67.5, which the DDet explosion attributes to the orbital motion of the exploding WD around its companion, can be an outcome of the explosion of a near-Chandrasekhar lonely WD; an off-center delayed-detonation transition explosion can form asymmetrical nucleosynthesis, while leading to a bulk motion of nickel that decays to iron. I repeat my claim that the CD scenario of a SNIP is the most likely scenario for SNR 0509-67.5.

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arXiv2026

The failed failed-supernova scenario of M31-2014-DS1

I examine a recently proposed failed-supernova scenario for the fading of the yellow supergiant event M31-2014-DS1, and find that it requires unlikely fine-tuned parameters to work, if at all. In the failed-supernova scenario, most of the yellow supergiant collapsed to form a black hole. Due to the energy carried by neutrinos from the cooling, collapsing core, gravity decreases, leading to the ejection of a small fraction of the outer envelope, some of which remains bound. The fallback accreted gas possesses large angular-momentum fluctuations due to the pre-collapse envelope convection. The fallback material forms intermittent accretion disks around the black hole that launch jets (or disk wind), which unbind most of the bound material. The failed-supernova scenario for M31-2014-DS1 requires that only <1% of the bound material be accreted by the black hole, but the jets do not shut down the backflow for over 10 years. I find this fine-tuned requirement unlikely. I also find that, due to the rapid radiative cooling of the outflow interaction zone with the outer gas, the expected radiation is about an order of magnitude or more above the observed value. These, as well as earlier challenges raised against the failed-supernova scenario, make the alternative type II intermediate-luminosity optical transient scenario, in which fading is due to dust ejection in a violent binary interaction, more likely. The fading event M31-2014-DS1 does not support the failed-supernova scenario predicted by the neutrino-driven explosion mechanism of core-collapse supernovae.

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arXiv2026

Simulating the convection in red super-giant stars: wobbling jets in common envelope evolution

We use our newly constructed three-dimensional red supergiant (RSG) stellar model, which also mimics nuclear energy production and photospheric emission, to calculate the stochastic component of the angular momentum of the mass that a companion spiraling within the RSG's envelope accretes during common envelope evolution (CEE). The accreted mass has a fixed-direction angular-momentum component arising from the density gradient in the RSG envelope and orbital motion. The angular momentum component with a stochastically varying direction results from vigorous envelope convection. We do not include the companion's influence on the RSG envelope during the CEE and consider an undisturbed, non-rotating RSG stellar model. We find that the fluctuating angular momentum amplitude can be several times the fixed-axis angular momentum. The total specific angular momentum of the accreted mass easily forms intermittent accretion disks around neutron stars and black holes, but it is only marginally sufficient, or not at all, to form accretion disks around main-sequence stellar companions. The intermittent accretion disks we expect to form will launch wobbling jets with varying axes. We discuss aspects of wobbling jets in the CEE and the grazing envelope evolution (GEE), which might precede the CEE or replace it altogether. Studies have claimed that jets are a crucial ingredient in many cases of CEE, and the standard CEE should include jets that the companion launches, before (like the GEE), during, and/or at the exit from the CEE. Our study supports this claim and emphasizes the importance of wobbling jets.

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arXiv2026

Identifying a circum-jet southern ring counterpart to the northern jet of the Crab Nebula

I analyze images of the Crab Nebula core-collapse supernova (CCSN) remnant in light of recent three-dimensional hydrodynamical simulations of the jittering-jets explosion mechanism (JJEM) and identify a southern ring opposite to the northern jet, which I attribute to a counterjet. The Crab Nebula is known for its point-symmetric morphology of seven pairs of bays and a pair of two filaments, but no pairs of two jets or their direct outcomes, like ears and rings, have been identified. I identify a ring in visible and infrared images of the Crab Nebula opposite to the prominent northern jet. Recent hydrodynamical simulations of the JJEM show that jets that explode CCSNe can form such circum-jet rings. I, therefore, attribute the shaping of the southern ring to a southern jet, a counter jet to the northern jet, both of which participated in the explosion of the Crab Nebula in the framework of the JJEM.

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arXiv2026

JWST observations support the jittering-jets explosion mechanism (JJEM) for the core-collapse supernova remnant SNR 0540-69.3

We examine published JWST observations of the core-collapse supernova (CCSN) remnant SNR 0540-69.3 and identify a point-symmetric morphology in its inner ejecta. Within the framework of the jittering jets explosion mechanism (JJEM), we interpret this morphology as evidence that the ejecta were shaped by two, and likely three or more, pairs of jets during the explosion process. Both visual inspection and a recently developed quantitative symmetry-identification method for astrophysical imaging reveal an approximate rotational symmetry between the northeastern redshifted ejecta and the southwestern blueshifted ejecta. Each side contains clumps (knots) surrounding a previously identified cavity, with the best quantitative correspondence obtained for a rotation of 189°. We further identify a symmetry center that is offset from the current pulsar position, strengthening an earlier claim for a pulsar kick. We interpret the pair of cavities and their surrounding clumpy structures as having been shaped by multiple jet-launching episodes. In addition, we identify a pair of opposing nozzles at a large angle to the cavities, which we attribute to another jet pair. Guided by the similarities to point-symmetric planetary nebulae shaped by jets and by recent three-dimensional hydrodynamical simulations of the JJEM, we conclude that the inner ejecta were shaped by at least three jet pairs launched by the neutron star after it acquired its kick velocity, consistent with the JJEM.

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arXiv2026

Simulating observed point-symmetric core-collapse supernova morphologies with the jittering jets explosion mechanism

We conduct two three-dimensional hydrodynamic simulations of the jittering-jets explosion mechanism (JJEM) of core-collapse supernova (CCSN), launching three pairs of inclined opposite jets into the core of an enveloped-stripped stellar model, and reproduce some morphological features of observed CCSN remnants (CCSNRs) that a single pair of jets or instabilities alone cannot reproduce. We launch the three pairs of jets within about a second, and follow the ejecta for more than 10 seconds until after shock breakout. Our main findings are: (1) Although the jets are choked deep inside the star, they manage to form a pronounced multipolar (point-symmetric) morphology. (2) Instabilities and vortices resulting from the jet-star interaction form small clumps and narrow filaments, some of which form point-symmetric morphology, resembling some observed CCSNRs. (3) The most energetic jet of one simulation forms a large low-density blowout ahead of the ejecta, with filaments dragging behind it, resembling the blowout of the Cygnus Loop. (4) The inner ejecta presents two symmetry axes along two of the three jet axes: one of a pair of rings and one of a pair of nozzles, resembling the structure of the point-symmetric SNR J0450.4-7050. (5) The three pairs of jets compress two dense blocks between their axes. The blocks exhibit a Doppler-shift bipolar outflow highly inclined to the morphological axes along the jet axes. The inclined Doppler-bipolar outflow and morphology axis resembles the CCSNRe W49B and SNR G292.0+1.8. Our study supports the claim that the JJEM is the primary explosion mechanism of CCSNe.

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arXiv2026

Building three-dimensional giant stellar models for common envelope simulations

We build a three-dimensional (3D) red supergiant (RSG) stellar model for common envelope evolution (CEE) simulations by transporting a 1D stellar model to a 3D numerical grid, mimicking core nuclear power by depositing energy to an inner shell, and mimicking stellar emission by cooling grid cells with densities below the photospheric density. We do not relax the model; rather, we let it perform its natural pulsation. We find that when we mimic photospheric emission by cooling low-density grid cells, the oscillations slowly decay on a time scale much longer than in the absence of photospheric cooling. When we mimic both nuclear energy production, by depositing the stellar luminosity in an inner shell above the inert core of the stellar model, and the photospheric cooling, the oscillations do not decay and their amplitude slowly increases with time. The main pulsational period is about 1 year, comparable to the stellar dynamical time, suggesting a fundamental radial pulsation mode. The non-spherical structure of the stellar model and rapid low-amplitude temporal variations in the average stellar radius testify to the presence of non-radial oscillation modes on top of the fundamental radial mode. We also obtain vigorous convection, as RSG stars have. We conclude that the best way of preparing a giant star to simulate CEE and grazing-envelope evolution is to deposit energy with the stellar luminosity in an inner shell, and to cool the outer low-density numerical shell. There is no need to relax the model.

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arXiv2026

Reproducing morphological features in the supernova remnant G11.2-0.3 by simulating jittering jets

We hydrodynamically simulate a core-collapse supernova (CCSN) explosion by launching three pairs of jets in the framework of the jittering-jets explosion mechanism (JJEM), and reproduce a morphology of two opposite circum-jet rings and a bar of dense gas perpendicular to the rings' axis, resembling these morphological features in the CCSN remnant SNR G11.2-0.3. The first pair of wide jets is very energetic; it triggers the explosion and inflates two bubbles that compress the material in an expanding shell. The bubbles also compress material in a plane perpendicular to the jet axis. The second pair of wide jets removes material from this plane, beside along a bar that is on an axis perpendicular to the two pairs' axes. The jets of the third pair, now of narrow jets, penetrate the expanding shell and compress material to their sides to form two opposite rings. These morphological features are qualitatively similar to those observed in the point-symmetric CCSN remnant G11.2-0.3. As competing theoretical CCSN explosion mechanisms cannot explain point-symmetric CCSN remnants, our study provides some support for the claim that the JJEM is the primary explosion mechanism of CCSNe.

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arXiv2026

Type Ia supernovae interacting with a close circumstellar material (SNe Ia-CSM) are SNe Ia inside planetary nebulae (SNIPs)

I show that a newly estimated fraction of normal type Ia supernovae (SNe Ia) that interact within about 100 days of explosion with circumstellar material (CSM), called SNe Ia-CSM, is compatible with a recently estimated fraction of normal SNe Ia that interact with an old planetary nebula, hence, supporting the core-degenerate (CD) scenario for normal SNe Ia. According to the CD scenario, a white dwarf (WD) merges with the core of an asymptotic giant branch star at the end of common envelope evolution (CEE) and forms a massive WD remnant close to the Chandrasekhar mass. The CEE ejects a planetary nebula that the WD remnant ionizes. Most explosions occur within a merger-to-explosion delay (MED) time of less than a million years, before the planetary nebula material disperses to the interstellar medium, leading to a SN Ia inside a planetary nebula (SNIP). I discuss two plausible MED time distributions and show that the newly determined SNe Ia-CSM fraction of all normal SNe Ia, ~0.04%, is compatible with the SNIP fraction of ~80%. Therefore, although the fraction of SNe Ia-CSM is very small, it does not require a rare evolutionary pathway. I argue that SNe Ia-CSM follow the same scenario that accounts for 70%-90% of all normal SNe Ia, namely, the CD scenario.

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arXiv2026

The jet-shaped pipe morphology in planetary nebulae and core-collapse supernova remnants

We compare images of core-collapse supernova (CCSN) remnants (CCSNRs) and jet-shaped planetary nebulae (PNe) that have a narrow, faint zone extending from side to side, termed a pipe, with a hydrodynamical numerical simulation exploding a massive star with three pairs of jets in the framework of the jittering jets explosion mechanism (JJEM), and conclude that jets shaped the pipes in these CCSNRs and PNe. We present two jet-shaped PNe with a pipe and three PNe with two opposite narrow jet-shaped lobes, and argue that in some cases the two opposite narrow lobes might merge to form one long, faint zone extending from side to side of the PN, namely, a pipe. From the qualitative similarity of the pipe morphology of the two CCSNRs we analyze with the pipe of the PNe, we suggest that jets also shaped the pipe of these CCSNRs. We strengthen this conclusion with a three-dimensional hydrodynamic simulation that reproduces two opposite narrow lobes, similar to those observed in PNe with lobes. These lobes can merge later to form a pipe. This paper is another in a series that strengthen the case for the JJEM as the primary explosion mechanism of CCSNe by comparing CCSNR morphologies with those of jet-shaped PNe.

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arXiv2026

JWST observations of a planetary nebula support jet-driven explosion of core-collapse supernova remnant RCW 103

We show that the morphology of the core-collapse supernova (CCSN) remnant RCW 103 is very similar to the morphology of the brightest regions in the recently released JWST IR images of the jet-shaped planetary nebula (PN) PMR 1, and conclude that two energetic pairs of jets shaped RCW 103, compatible with the jittering-jets explosion mechanism (JJEM). The PN PMR 1 IR image exhibits two opposite, large, and prominent ears with a narrow, faint region connecting them through the center, a pipe. Observations and simulations have shown that a pair of jets inflates such a pair of ears in PNe. The brightest regions of PN PMR 1 form two clumpy sectors, each shaped like a wide pizza slice, with a faint region between them; the CCSN remnant RCW 103 has a very similar morphology. We identify two shells in the X-ray image of RCW 103 and suggest that two close pairs of energetic jets shaped this CCSN remnant. We find only traces of two of the four expected ears in RCW 103. The ears in RCW 103 were already dispersed and are very faint. Deeper X-ray observations might detect them. Such energetically misaligned pairs of jets are compatible with the JJEM, which predicts that a few to about 20 pairs of jets are responsible for most CCSN explosions.

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arXiv2026

Jittering jets promote dust formation in core-collapse supernovae

I find that the dust morphologies in some core-collapse supernova (CCSN) remnants (CCSNRs) possess jet-shaped morphologies, and propose that the properties of the jets that explode the CCSNe and their interaction with the core and envelope (if it exists) are among the factors that determine the amount of dust formed and its morphology. I find that some of the dust-rich structures in the CCSNRs Cassiopeia A and the Crab Nebula are distributed in point-symmetric morphologies, and that the dust in SN 1987A follows the bipolar morphology of the inner ejecta. Earlier studies attributed these morphologies in CCSNRs to jet shaping within the jittering jets explosion mechanism (JJEM). These dust morphologies suggest, within the framework of the JJEM, that exploding jets enhance dust formation in CCSNRs. This study contributes to the diversity of processes in which CCSN exploding jets are involved and to establishing the JJEM as the primary explosion mechanism of CCSNe.

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arXiv2026

The early r-process nucleosynthesis scenarios

I compare seven actively studied r-process nucleosynthesis scenarios against observed properties of r-process elements in the early Universe, and conclude that the most likely scenario to contribute to the site of elements below the third r-process peak is the magnetorotational r-process scenario, and that of the third peak is the common envelope jets supernova (CEJSN) r-process scenario. The collapsar and CEJSN r-process scenario might also contribute to the lighter r-process elements, and the binary neutron star (NS-NS) merger r-process scenario might contribute to the third r-process peak. The magnetar, the wind from the newly born NS, and the accretion-induced collapse of a white dwarf r-process scenarios fall short in explaining observations. They might exist, but cannot be major contributors to the r-process in the early Universe. To constrain r-process scenarios in the early Universe, I require that they explain the large scatter in the r-process abundances of very metal-poor stars, account for the correlation between light r-process nucleosynthesis and iron production, and the lack of correlation between the third peak r-process production and iron production, as inferred from very metal-poor stars. I discuss the diversity of the CEJSN r-process scenario and encourage extending its exploration.

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arXiv2026

Simulating the jittering-jets explosion mechanism: circum-jet rings account for observed core-collapse supernova remnant morphologies

We conduct three-dimensional hydrodynamical simulations of core-collapse supernova (CCSN) explosion driven by jets in the framework of the jittering jets explosion mechanism (JJEM), and obtain a pair of opposite circum-jet rings similar to those observed in some CCSN remnants (CCSNRs). We launch two pairs of jets along the same axis, the first of two opposite wide jets, and the second of narrow jets. The wide jets compress the core of a stripped-envelope stellar model to form a dense, fast-expanding shell. The narrow jets catch up with the dense shell, penetrate it, and compress the gas to the sides, forming the two opposite rings. At high inclination angles of the jets' axis to the line of sight, the projection of each ring on the plane of the sky forms two bright zones, where the rings cross the plane of the sky. This morphology explains that of SNR G46.8-0.3. At intermediate inclination angles, the rings are fully visible as two opposite bright elliptical rims. Our simulations explain the two prominent rings on the outer shell of CCSNR G11.2-0.3. Our results strengthen the claim that the JJEM is the primary explosion mechanism of CCSNe.

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