arXiv subjects

Dmitry Shishkin

Publications and source records attributed to Dmitry Shishkin.

15 recordsLinked to original sources

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{\deg}. 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

The precessing jet axis of the supernova remnant 3C 397

We identify an S-shaped morphological feature in the enigmatic supernova remnant (SNR) 3C 397, which we attribute to the shaping by a precessing pair of jets during the explosion. We identify an S-shaped, faint region composed of two bubbles, located to the north and south of the center, between two X-ray-bright sides. We attribute the S-shape to a pair of precessing jets that were part of the explosion process. The identification of a main jet axis in SNR 3C 397 increases its similarity to the enigmatic SNR W49B. We discuss two possible scenarios for SNR 3C 397 and W49B. (1) The thermonuclear common-envelope-jet supernova scenario, which was suggested before for W49B, where a neutron star destroys a white dwarf and accretes part of the white dwarf's material via an accretion disk that undergoes a thermonuclear outburst and launches the jets. (2) The collapse-induced thermonuclear jet-driven explosion, which is a core-collapse supernova driven by jets, as in the majority of, or even all, core-collapse supernovae, and in addition, there is a thermonuclear outburst of a rare helium-oxygen mixed layer in the core, which is triggered by the core collapse. Our study emphasizes the primary role of jets even in the enigmatic SNR 3C 397.

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arXiv2026

Quantifying Symmetry: Transformation Information for Planetary Nebulae and Supernova Remnants

We present a quantitative symmetry-identification pipeline for astrophysical images based on Transformation Information (TI), an information measure of self-similarity under geometric transformations. TI is expressed as a Kullback-Leibler (cross-entropy) divergence between an image and its rotated or reflected counterpart on the overlapping domain. By scanning rotation angles and reflection axes, we obtain TI curves whose local minima identify symmetry operations. We validate the method on a wind-rose pattern and then apply it to planetary nebulae, where the recovered axes trace bipolar and multipolar lobes consistent with morphology-based classifications. Applying TI to supernova remnants yields estimate axes associated with protrusions, rims, and substructure. To emphasize global morphology, we introduce a thresholded two-level variant that compares binary silhouettes and can reveal outline-driven symmetries. Finally, we quantify symmetry using a minima prominence-to-width score and show that this compact descriptor separates Type Ia and core-collapse remnants into distinct populations for an X-ray sample. TI provides a non-parametric, reproducible framework for symmetry identification, classification and population studies.

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arXiv2025

Jittering jets in stripped-envelope core-collapse supernovae

Using the one-dimensional stellar evolution code MESA, we find that all our models in the initial mass range of 12-40 Mo, regardless of whether they have hydrogen-rich, hydrogen-stripped, or helium+hydrogen-stripped envelopes, have at least one significant strong convective zone in the inner core, which can facilitate the jittering-jets explosion mechanism (JJEM). We focus on stripped-envelope CCSN progenitors that earlier studies of the JJEM did not study, and examine the angular momentum parameter j=rVconv, where r is the radius of the layer and Vconv is the convective velocity according to the mixing length theory. In all models, there is at least one prominent convective zone with j>2e15 cm^2/s inside the mass coordinate that is the maximum baryonic mass of a neutron star (NS), m=2.65 Mo. According to the JJEM, convection in these zones seeds instabilities above the newly born NS, leading to the formation of intermittent accretion disks that launch pairs of jittering jets, which in turn explode the star. Our finding is encouraging for the JJEM, although it does not show that the intermittent accretion disks indeed form. We strengthen the claim that, according to the JJEM, there are no failed CCSNe and that all massive stars explode. In demonstrating the robust convection in the inner core of stripped-envelope CCSN progenitors, we add to the establishment of the JJEM as the primary explosion mechanism of CCSNe.

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arXiv2025

Natal kick by early-asymmetrical pairs of jets to the neutron star of supernova remnant S147

We analyze the bipolar morphology of the jet-shaped core-collapse supernova (CCSN) remnant (CCSNR) S147 and its neutron star (NS) kick velocity, and suggest that two pairs of unequal, opposite jets contributed to the NS kick velocity. This kick by early asymmetrical pairs (kick-BEAP) of jets mechanism operates within the framework of the jittering jets explosion mechanism (JJEM). We examine the prominent pair of large ears and, based on their flat structure rather than the more common conical structure of ears, conclude that two pairs of jets close in angle inflated the two opposite ears. We connect two opposite X-ray bright zones by an additional axis to create the full point-symmetric morphology of CCSNR S147. We propose that the two unequal jets that formed the X-ray bright zones imparted the first kick-BEAP, while the two pairs of jets that formed the ears imparted the second kick-BEAP. The two kick velocities are of about equal magnitude of ~450 km/s, which implies very energetic jets. Such jets can excite gravitational waves that present detectors can detect from the Galaxy and the Magellanic Clouds. We use the morphology we identify to estimate the CCSNR age at 23,000 yr. Our results strengthen the JJEM.

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arXiv2025

The main jet axis of the W49B supernova remnant

We identify an axis connecting two opposite `ears' in the supernova remnant W49B and morphological signatures of three arcs around this axis that we claim are sections of full circum-jet rings. Based on recent identifications of morphological signatures of jets in core-collapse supernovae (CCSNe), including ejecta-rich axes, we reexamine images of W49B and identify a heavy element-rich protrusion (ear) as a jet-inflated structure. We identify the opposite ear and a clump at its tip as the signature of the opposite jets. The line connecting the two clumps at the tips of the two opposite ears forms the main jet axis of W49B. We compare the three arcs around the main jet axis in W49B to the circum-jet rings of the jets in the Cygnus A galaxy and deduce that these arcs are sections of full circum-jet rings in W49B. In W49B, the jets are long gone, as in some planetary nebulae with circum-jet rings. Identifying the main jet axis is incompatible with a type Ia supernova. It leaves two possibilities: that jets exploded W49B as a CCSN, i.e. the jittering jets explosion mechanism where the pair of jets we identify is one of many that exploded the star, or that the explosion was a common envelope jet supernova with a thermonuclear outburst, i.e., both the pair of jets and thermonuclear outburst exploded the core of a red supergiant star as a pre-existing neutron star tidally destroyed it.

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arXiv2024

Et tu, Brute?: The Crab Nebula also exploded by jittering jets

We identify a point-symmetrical morphology comprised of seven pairs of opposite bays in the core-collapse supernova (CCSN) remnant Crab Nebula, which is consistent with the jittering jets explosion mechanism (JJEM) of CCSNe. We use a recently published infrared image of the Crab Nebula and apply image analysis to fit seven pairs of bays in the Crab, each pair of two bays and a symmetry axis connecting them. The seven symmetry axes intersect close to the explosion site, forming a point-symmetrical structure. We explain the bays as clumps that move slower than the low-density ejecta that the pulsar accelerated. Jittering jets that exploded the Crab formed the clumps during the explosion process. This shows that jittering jets explode even very low-energy CCSNe, as the Crab is, adding to the solidification of the JJEM as the primary explosion mechanism of CCSNe.

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arXiv2024

The Puppis A supernova remnant: an early jet-driven neutron star kick followed by jittering jets

We identify a point-symmetric morphology of three pairs of ears/clumps in the core-collapse supernova remnant (CCSNR) Puppis A, supporting the jittering jets explosion mechanism (JJEM). In the JJEM, the three pairs of jets that shaped the three pairs of ears/clumps in Puppis A are part of a large, about 10 to 30 pairs of jets that exploded Puppis A. Some similarities in morphological features between CCSNR Puppis A and three multipolar planetary nebulae considered to have been shaped by jets solidify the claim for shaping by jets. Puppis A has a prominent dipole structure, where one side is bright with a well-defined boundary, while the other is faint and defused. The neutron star (NS) has a natal kick velocity in the opposite direction to the denser part of the dipole structure. We propose a new mechanism in the frame of the JJEM that imparts a natal kick to the NS, the kick-by-early asymmetrical pair (kick-BEAP) mechanism. At the early phase of the explosion process, the NS launches a pair of jets where one jet is much more energetic than the counter jet. The more energetic jet compresses a dense side to the CCSNR, and, by momentum conservation, the NS recoils in the opposite direction. Our study supports the JJEM as the primary explosion mechanism of core-collapse supernovae and enriches this explosion mechanism by introducing the novel kick-BEAP mechanism.

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arXiv2024

The vela supernova remnant: The unique morphological features of jittering jets

We identify an S-shaped main-jet axis in the Vela core-collapse supernova (CCSN) remnant (CCSNR) that we attribute to a pair of precessing jets, one of the tens of pairs of jets that exploded the progenitor of Vela according to the jittering jets explosion mechanism (JJEM). A main-jet axis is a symmetry axis across the CCSNR and through the center. We identify the S-shaped main-jet axis by the high abundance of ejecta elements, oxygen, neon, and magnesium. We bring the number of identified pairs of clumps and ears in Vela to seven, two pairs shaped by the pair of precessing jets that formed the main-jet axis. The pairs and the main-jet axis form the point-symmetric wind-rose structure of Vela. The other five pairs of clumps/ears do not have signatures near the center, only on two opposite sides of the CCSNR. We discuss different possible jet-less shaping mechanisms to form such a point-symmetric morphology and dismiss these processes because they cannot explain the point-symmetric morphology of Vela, the S-shaped high ejecta abundance pattern, and the enormous energy to shape the S-shaped structure. Our findings strongly support the JJEM and further severely challenge the neutrino-driven explosion mechanism.

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arXiv2024

Identifying jittering-jet-shaped ejecta in the Cygnus Loop supernova remnant

Analyzing images of the Cygnus Loop, a core-collapse supernova (CCSN) remnant, in different emission bands, we identify a point-symmetrical morphology composed of three symmetry axes that we attribute to shaping by three pairs of jets. The main jet axis has an elongated S shape, appearing as a faint narrow zone in visible and UV. We term it the S-shaped hose, and the structure of three symmetry lines, the point-symmetric wind rose. The two other lines connect a protrusion (an ear or a bulge) with a hole on the opposite side of the center (a nozzle or a cavity), structures that we identify in the X-ray, UV, visible, IR, and/or radio images. There is a well-known blowout at the southern end of the S-shaped hose, and we identify a possible opposite blowout at the northern end of the S-shaped hose. The point-symmetrical morphology of the Cygnus Loop is according to the expectation of the jittering jets explosion mechanism (JJEM) of CCSNe, where several to few tens of pairs of jets with stochastically varying directions explode the star. The three pairs of jets that shaped the wind-rose structure of the Cygnus Loop are the last energetic pairs of this series of jets. Our study further supports the JJEM as the main explosion mechanism of CCSNe.

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arXiv2024

The jittering jets explosion mechanism (JJEM) in electron capture supernovae

We conduct one-dimensional stellar-evolution simulations of stars with zero age main sequence masses of $M_{ZAMS} = 8.8-9.45 M_\odot$ towards core collapse by electron capture, and find that the convective zone of the pre-collapse core can supply the required stochastic angular momentum fluctuations to set a jet-driven electron capture supernova (ECSN) explosion in the frame of the jittering jets explosion mechanism (JJEM). By our assumed criteria of a minimum convective specific angular momentum and an accreted mass during jet-launching of $M_{acc} \simeq 0.001-0.01 M_\odot$, the layer in the convective zone that when accreted launches the exploding jittering jets resides in the helium-rich zone. Depending on the model, this exploding layer is accreted at about a minute to a few hours after core collapse occurs, much shorter than the time the exploding shock crosses the star. The final (gravitational) mass of the neutron star (NS) remnant is in the range of $M_{NS} =1.25-1.43 M_\odot$.

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arXiv2023

The implications of large binding energies of massive stripped core collapse supernova progenitors on the explosion mechanism

We examine the binding energies of massive stripped-envelope core collapse supernova (SECCSN) progenitors with the stellar evolution code MESA, and find that the jittering jets explosion mechanism is preferred for explosions where carbon-oxygen cores with masses of $>20 M_\odot$ collapse to leave a neutron star (NS) remnant. We calculate the binding energy at core collapse under the assumption that the remnant is a NS. Namely, stellar gas above mass coordinate of $~1.5-2.5 M_\odot$ is ejected in the explosion. We find that the typical binding energy of the ejecta of stripped-envelope progenitors with carbon-oxygen core masses of $M_{CO} > 20 M_\odot$ is $E_{bind}>2 \times 10^{51} erg$. We claim that jets are most likely to explode such cores as jet-driven explosion mechanisms can supply high energies to the explosion. We apply our results to SN 2020qlb, which is a SECCSN with a claimed core mass of $~30-50 M_\odot$, and conclude that the jittering jets explosion mechanism best accounts for such an explosion that leaves a NS.

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arXiv2022

Remnant masses of core collapse supernovae in the jittering jets explosion mechanism

We conduct one dimensional (1D) stellar evolution simulations of non-rotating stars with initial masses in the range of $11-48 M_\odot$ to the time of core collapse and, using a criterion on the specific angular momentum fluctuations in the inner convective zones, estimate the masses of the neutron star (NS) remnants according to the jittering jets explosion mechanism. From the 1D simulations we find that several convective zones with specific angular momentum fluctuations of $j_{conv} > 2.5 \times 10^{15} cm^2 s^{-1}$ develop near the edge of the iron core in all models. For this condition for explosion we find the NS remnant masses to be in the range of $1.3 -1.8 M_\odot$, while if we require twice as large values, i.e., $j_{conv} > 5 \times 10^{15} cm^2 s^{-1}$, we find the NS remnant masses to be in the range of $1.4 - 2.8 M_\odot$ (the upper values here might form black holes). Note that in general the formation of black holes in the jittering jets explosion mechanism requires a rapidly rotating pre-collapse core, while we simulate non-rotating stars.

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arXiv2021

Supplying angular momentum to the jittering jets explosion mechanism using inner convection layers

We conduct one-dimensional stellar evolution simulations in the mass range $13-20 M_{\odot}$ to late core collapse times and find that an inner vigorous convective zone with large specific angular momentum fluctuations appears at the edge of the iron core during the collapse. The compression of this zone during the collapse increases the luminosity there and the convective velocities, such that the specific angular momentum fluctuations are of the order of j_{conv}~5x10^15cm^2/sec. If we consider that three-dimensional simulations show convective velocities that are three to four times larger than what the mixing length theory gives, and that the spiral standing accretion shock instability in the post-shock region of the stalled shock at a radius of ~100km amplify perturbations, we conclude that the fluctuations that develop during core collapse are likely to lead to stochastic (intermittent) accretion disks around the newly born neutron star. In reaching this conclusion we also make two basic assumptions with uncertainties that we discuss. Such intermittent disks can launch jets that explode the star in the frame of the jittering jets explosion mechanism.

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arXiv2020

Eccentric grazing envelope evolution towards type IIb supernova progenitors

We simulate the evolution of eccentric binary systems in the frame of the grazing envelope evolution (GEE) channel for the formation of Type IIb supernovae (SNe IIb), and find that extra mass removal by jets increases the parameter space for the formation of SNe IIb in this channel. To explore the role of eccentricity and the extra mass removal by jets we use the stellar evolutionary code MESA binary. The initial primary and secondary masses are M1i=15Mo and M2i=2.5Mo. We examine initial semi-major axes of 600-1000Ro, and eccentricities of e=0-0.9. Both Roche lobe overflow (RLOF) and mass removal by jets, followed by a wind, leave a hydrogen mass in the exploding star of M(H,f)=0.05Mo, compatible with a SN IIb progenitor. When the initial orbit is not circular the final orbit might have a very high eccentricity. In many cases, with and without the extra mass removal by jets, the system can enter a common envelope evolution (CEE) phase, and then gets out from it. For some ranges of eccentricities the jets are more efficient in preventing the CEE. Despite the large uncertainties, extra mass removal by jets substantially increases the likelihood of the system to get out from a CEE. This strengthens earlier conclusions for circular orbits. In some cases RLOF alone, without mass removal by jets, can form SN IIb progenitors. We estimate that the extra mass removal by jets in the GEE channel increases the number of progenitors relative to that by RLOF alone by about a factor of two.

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