We identify a pointsymmetric morphology of three pairs of earsclumps in the corecollapse supernova CCSN 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 earsclumps 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 welldefined boundary while the other is faint and defused. The neutron star NS remnant of Puppis A has a proper velocity its 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 kickbyearly asymmetrical pair kickBEAP 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 CCSNe and enriches this explosion mechanism by introducing the novel kickBEAP mechanism.
['Astrophysics - High Energy Astrophysical Phenomena']
The Puppis A supernova remnant an early jetdriven neutron star kick followed by jittering jets
{'The Puppis A supernova remnant: an early jet-driven neutron star kick followed by jittering jets': 'Ealeal Bear, 1 Dmitry Shishkin, 1 and Noam Soker 1  \n1 Department of Physics, Technion, Haifa, 3200003, Israel; ealeal44@technion.ac.il; s.dmitry@campus.technion.ac.il; soker@physics.technion.ac.il  \n(Dated: July 2024)', 'ABSTRACT': 'We identify a point-symmetric morphology of three pairs of ears/clumps in the core-collapse supernova (CCSN) 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) remnant of Puppis A has a proper velocity, its 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 CCSNe and enriches this explosion mechanism by introducing the novel kick-BEAP mechanism.  \nKeywords: supernovae: general - stars: jets - ISM: supernova remnants - stars: massive', '1. INTRODUCTION': "In the jittering jets explosion mechanism (JJEM; Papish & Soker 2011) of core-collapse supernovae (CCSNe), pairs of opposite jets with stochastically (fully or partially) varying directions explode the star. The newly born neutron star (NS; and the black hole, in cases where the NS collapses into a black hole) launches several to few tens of pairs of jets on a time scale of ≈ 0 . 5 -10 s (e.g., Soker 2024a) as it accretes mass from the collapsing core via intermittent accretion disks (later pairs of jets are possible). In the present study, we will propose that the first jets are launched already at t b ≃ 0 . 1 -0 . 2 s post-bounce (Section 5). The stochastic angular momentum of the gas that feeds the intermittent accretion disks results from instabilities above the NS that increase the angular momentum seed fluctuations of the collapsing gas. These instabilities above the NS and below the stalled shock at ≃ 150 km from the center include the modes of spiral standing accretion shock instability (e.g., Buellet et al. 2023 for a recent study of this instability). The seed fluctuations come from the  \nconvective motion in the pre-collapse core (e.g., Papish & Soker 2014; Gilkis & Soker 2014, 2016; Shishkin & Soker 2023; Wang et al. 2024). Neutrino heating boosts the explosion process in the JJEM (Soker 2022a), but the jets play the primary role in the explosion process.  \nIn the competing delayed neutrino explosion mechanism of CCSNe (e.g., Andresen et al. 2024; Burrows et al. 2024b; Janka & Kresse 2024; Muller 2024; Muller et al. 2024; Nakamura et al. 2024; van Baal et al. 2024; Wang & Burrows 2024; Laplace et al. 2024 for some very recent studies) neutrino heating revives the stalled shock and explode the star; jets play no roles in the explosion process. The jet-based magnetorotational explosion mechanism requires a rapidly rotating pre-collapse core to launch jets along a fixed axis (e.g., Shibagaki et al. 2024; Zha et al. 2024 for recent studies of this mechanism); therefore, it can power only a very small fraction of CCSNe. We considered the magnetorotational explosion mechanism part of the neutrino-driven mechanism despite the powering by jets because it still attributes  \nmost CCSNe to the neutrino-driven mechanism. The JJEM attributes all CCSN explosions to jets.  \nThe observational property of CCSN remnants (CCSNRs) that best differentiates between the two explosion mechanisms is point-symmetric morphological features. A point-symmetric morphology has two or more pairs of structural features on opposite sides of the center that do not share the same symmetry axis. The opposite structures include clumps, filaments, bubbles (faint structures closed and encircled by a brighter rim), lobes, which are bubbles with partial rims, and ears. An ear is a protrusion from the main CCSNR shell with decreasing cross sections away from the center.  \nWhile the JJEM predicts that many, but not all, CCSNR morphologies are point symmetric, the neutrinodriven explosion mechanism has no explanation for most of these morphologies (for a detailed comparison between the two explosion models, see Soker & Shishkin 2024). The following is the list of CCSNRs with studies that attributed their point-symmetric morphologies to the JJEM: SNR 0540-69.3 (Soker 2022b), the Vela CCSNR (Soker 2023; Soker & Shishkin 2024), CTB 1 (Bear & Soker 2023), N63A (Soker 2024b), SN 1987A (Soker 2024c,a), G321.3-3.9 (Soker 2024d; Shishkin & Soker 2024), G107.7-5.1 (Soker 2024d), Cassiopeia A (Bear & Soker 2024), and the Cygnus Loop (Shishkin et al. 2024). Some other CCSNRs show only one pair of opposite ears (e.g., Grichener & Soker 2017). Some other CCSNRs are challenging in having a complicated structure lacking clear symmetry; the CCSNR Puppis A is such a CCSNR.  \nEarlier studies have argued for the jet-shaping of Puppis A. Castelletti et al. (2006) consider jet shaping at very late times rather than exploding jets. Grichener & Soker (2017) consider shaping by a pair of jets that are part of the jittering jets that exploded the progenitor of Puppis A, and estimate the energy of each of the two jets that inflated the western and eastern ears to be ≃ 1% of the explosion energy. Clearly, these two jets could not have by themselves exploded the star. We expect more pairs of jets, as we discuss in this study. Other studies noticed the interaction of Puppis A with a circumstellar material (CSM) or interstellar medium (ISM; e.g., Dubner et al. 2013; Dubner & Giacani 2015; Reynoso & Walsh 2015; Meyer et al. 2022). However, Reynoso et al. (2017) find no strong indication for ejecta-cloud interaction in the east. In any case, although the ISM influences the morphology of old CCSNRs (e.g., Sofue 2024 for a recent paper), it cannot account for pointsymmetry and asymmetrical metal distribution as observed in many CCSNRs (e.g., Soker & Shishkin 2024).  \nThis study considers the shaping jets part of the exploding jets. The similarities of pairs of ears, a main line of symmetry (main jet axis), and, above all, pointsymmetric morphologies of many CCSNRs to similar structures in planetary nebulae (e.g., Bear et al. 2017; Bear & Soker 2017, 2018a; Soker 2022c, 2024e) and cooling flow clusters (Soker 2024d) support the claim of shaping by energetic jets. Several properties, like the large volume of some jet-shaped structures, indicating energetic jets, and the high abundance of heavy elements in some jet-shaped structures show that the NS launched the shaping jets during the explosion process and that the jets have powered the explosion (Soker & Shishkin 2024).  \nIn this study, we analyze the highly asymmetrical CCSNR Puppis A. We describe its structure as appears in observations of earlier studies but emphasize its point-symmetrical morphology and highly asymmetrical dipole structure (Section 2). In Section 3 we compare Puppis A's highly asymmetrical dipole structure to that of the SNR N49. In Section 4, we find some similarities with planetary nebulae that strengthen the claim for shaping by jets. In Section 5, we propose a novel mechanism for the kick velocity unique to the JJEM. We summarize this study in Section 6.", '2. THE POINT-SYMMETRIC STRUCTURE OF PUPPIS A': "Puppis A is a CCSN projected inside the Vela CCSNR. Its morphology and structure are highly nonspherical, and it has attracted attention over the years (e.g., Arendt et al. 1990; Hwang et al. 2005; Castelletti et al. 2006; Katsuda et al. 2010; Hewitt et al. 2012; Dubner et al. 2013; Reynoso et al. 2017, 2018; Aruga et al. 2022; Krivonos et al. 2022; Mayer et al. 2022; Giuffrida et al. 2023; Ghavamian et al. 2024). In this study, we concentrate on two aspects of its morphology. (1) We reveal a possible point-symmetric structure of three pairs of 'ears' (one pair of the three is more of two clumps). An 'ear' is a protrusion from the SNR's central nebula with a base smaller than the main SNR and a crosssection that decreases outward. The ear might appear differently from the main SNR, like being fainter. (2) The prominent dipole asymmetry (below and in more detail in Section 3), and in Section 5, we suggest a new mechanism to impart a kick velocity to the newly born NS that we suggest shaped the dipole asymmetry.  \nIn Figure 1 we present an X-ray image of Puppis A, using data from the early data release (EDR) of eROSITA (Obs ID: 700195). We added three lines connecting three pairs of ears, A with A ' , B with B ' , and C with C ' (which can also be classified as a pair of clumps). Earlier stud-  \nentified the pair AA ' . Grichener & Soker (2017) estimated that the combined energy of the two jets that inflated ears A and A ' is ≃ 2% of the explosion energy of Puppis A. They also connect each ear to the NS rather than to each other. This forms a bent in the direction of the two ears. Namely, as seen from the NS, the two ears are not exactly opposite at 180 · to each other. We prefer to connect the pair AA ' with a straight line. We also identify the pairs BB ' and CC ' . These two pairs' northern ears overlap on the plane of the sky but are not parts of a single structure. We take it to imply that the two axes (lines) of pairs BB ' and CC ' are highly inclined to each other.  \nWe mark three central points on the image of Puppis A: the present location of the NS (red asterisk), the estimated location of the NS at the time of the explosion (red dot) determined from the proper velocity of the NS of v kick = 763 km s -1 (763 ± 73 km s -1 , Mayer et al. 2020; Holland-Ashford et al. 2017 give v kick = 437 km s -1 ), and an assumed SNR age of 4600 yr (Mayer et al. 2020; Aruga et al. 2022 give an age of ≃ 10 4 yr), and the average location of the three centers of the three symmetry lines (white asterisk). Although the three symmetry lines do not cross each other at the same point, they all cross between the initial (at the explosion time) and the present location of the NS. Considering also the highly non-spherical structure of Puppis A, namely, its prominent dipole structure, we believe the point-symmetric morphology is robust, although not easy to identify.  \nThe dipole prominent structure of Puppis A includes a radio and X-ray bright emission region in the northeast with a more or less straight and sharp boundary. The bright zone forms a saddle-like shape; hence, we call it the 'Saddle.' It is seen as a yellow-colored zone on panel b of Figure 2 and a brighter zone in panel d. On the opposite side, the southwest side of Puppis A, on the other hand, the CCSNR does not have a sharp boundary, and it is much fainter. The southwest farthest structure is a faint potential ear, which we term 'P-ear(?)', where the question mark indicates that future studies should determine whether it is an ear. Southeast of the P-ear, we notice a zone that is brighter than the P-ear in radio (panel c) and in X-ray (panel d in Figure 2), which we term the 'Tongue'. The bright saddle on one side of Puppis A and the faint P-ear + the tongue on the other are the prominent components of the dipole morphology of Puppis A.  \nIn addition to the point-symmetric structure and the large-scale dipole asymmetry, we point out a central band prominent in radio images of Puppis A (e.g., Castelletti et al. 2006; Reynoso et al. 2018) that we  \nterm the 'corridor'; we mark it on panel c of Figure 2. Castelletti et al. (2006)'s processed radio images (figures 5 and 6 in their paper) show a central band from northeast to southwest, the 'corridor.' It is consistent with a flatter (than the surroundings) spectral index, which, they claim, might imply a region with emission being more thermal emission-dominated (than synchrotrondominated). The motion of the NS from explosion to present (proper motion) is inside and almost along the corridor.  \nMayer et al. (2022) eROSITA observations show a prominent zone rich in ejecta material, namely, elements from the deep core of the progenitor, O, Ne, Mg, Si, S, and Fe. Mayer et al. (2022) mark in this zone the ejecta knot that was noticed by Katsuda et al. (2008) and the ejecta-rich region that was seen by Hwang et al. (2008). We mark this zone on panel a of Figure 2. Some studies attribute ejecta-rich clumps to jets and expect a symmetric structural feature on the other side of the center, as expected in the JJEM. A prominent example is the Vela SNR (Soker & Shishkin 2024). There is no ejectarich zone opposite the one northeast of Puppis A. However, we note that the tongue is on the opposite side of the ejecta-rich clumps, as we mark by the dashed-white line on panels a and d of Figure 2. At this time, we do not argue that the ejecta-rich zone and the tongue are opposite structural features formed by a pair of opposite jets. We only comment on the need for deeper observations to reveal the composition of the tongue and further exploit the structure of the ejecta-rich clump.  \nSome studies attribute the shaping to the wind of the progenitor of Puppis A, e.g., Reynoso et al. (2018). There is also a dense ISM around Puppis A (e.g., Aruga et al. 2022). We do not question whether pre-explosion blown CSM and the ISM play a role in shaping Puppis A. However, we also attribute substantial shaping to pairs of jets that exploded the progenitor of Puppis A. We base our claim on the three pairs of ears that form the point-symmetric morphological structure and the 'corridor' that extends more or less along the kick direction of the NS to the southwest, beyond the present location of the NS. In Section 4, we find morphological similarities between Puppis A and a few planetary nebulae that are thought to be shaped by jets. This further supports the claim for jet-shaping of Puppis A.  \nGhavamian et al. (2024) suggest the presence of a close companion to the progenitor of Puppis A that formed a funnel in the ejecta. They aim to explain the blueshifted series of nested, optically emitting rings near the center of Puppis A ('the Swirl'). We note that a binary companion might smear a point-symmetric morphology,  \nFigure 1. X-ray log scaled counts image of Puppis A in the 0 . 2 -2 . 4keV range taken from the eROSITA EDR data. Colors indicate different energy bands, with levels balanced for display purposes (legend at bottom left). We mark with light-blue lines two point symmetrical pairs of ears (AA ' , BB ' ) and one pair of clumps (CC ' ). We denote the center of each symmetry line (axis) with a blue dot and the total average projected location of the three centers with a white asterisk. We mark the present NS location with a red asterisk. A dashed white arrow shows the direction of the NS's proper motion. A red dot indicates the location of the NS at explosion based on the proper motion (Mayer et al. 2020). In an inset on the bottom right, we display a zoom-in on the central region of Puppis A; the red arrow indicates the NS's proper motion direction.  \n<!-- image -->  \nRight Ascention  \nas many other processes do, like interaction with a CSM and the ISM, the hot ejecta, and the NS natal kick.", '3. THE HIGHLY ASYMMETRICAL STRUCTURE OF N49': "We briefly mention the morphology of the CCSNR N49 in the Large Magellanic Cloud (other names are DEML190; LHA 120-N 49; MCSNRJ0526-6605). N49 shares some similarities with Puppis A, particularly a strong dipole asymmetry. However, there are two sig-  \nnificant differences. The first is that there is no secure identification of an NS in that remnant; the magnetar in its north SGR0526-66 (PSR B0525-66) is likely not associated with N49 (e.g., Gaensler et al. 2001; Park et al. 2020; Ghavam et al. 2024). The second difference from Puppis A is that we could not identify clear signatures of jets despite some ear-like structures. For these differences, we only briefly mention N49 here. In Figure 3 we present images of N49. There is a bright and dense  \nFigure 2. Puppis A morphological features. (a) X-ray counts image, with the Si/H abundances map from Mayer et al. (2022) (semi-transparent, ranging from 0 to 3). We denote the ejecta-rich clump, also enriched in O, Ne, Mg, S, and Fe (see Mayer et al. 2022 for details). We mark a southwest protrusion that we call the 'Tongue'. We draw a dashed white line between the ejecta-rich clump and the tongue, suggesting their potential formation in a pair of jets deserves further study. Two X-ray count contour lines outline the entire remnant and mark the higher-counts region in the northeastern part of Puppis A. (b) X-ray counts (green) and IR image (WISE, 22 µm , red). The yellow region at the NE part of the Puppis A SNR is where emission is strong in both X-ray and IR - which we nickname the 'Saddle'. We mark its northern and eastern edges. We also point at a potential ear (P-ear) that might be a counterpart to the saddle on the southwestern part of Puppis A. (c) Radio image of the spectral index distribution from Castelletti et al. (2006), in grayscale. With a dashed red line, we mark the darker central band in the image, corresponding to a flatter radio spectrum (see Castelletti et al. 2006 for details) and denote it the 'Corridor'. We also mark the NS kick direction (dashed white arrow) to note the small angle between the two. Contour lines are of X-ray emission from the original image by Castelletti et al. (2006) and are different from the contour lines in panel a. (d) X-ray counts image with all aforementioned relevant features we identified in Puppis A, as well as the point-symmetric wind-rose from Figure 1. A grid serves to guide the eye with the different features. All panels display the same region as Figure 1. In all panels, we note our proposed center (see Figure 1) with a white asterisk, and in panels a, c, and d, the NS location (red asterisk) and the calculated location of the NS at explosion (red dot).  \n<!-- image -->  \nzone in the southeast with a more or less straight outer boundary, resembling the bright-dense zone of Puppis A in the northeast, i.e., the 'Saddle' of Puppis A.  \nYamane et al. (2018) observed a cloud in the southeast rim of the main shell of N49 that interacts with N49. This influences the morphology in the southeast, where the density is high. However, an interaction with a cloud in the southeast cannot explain some other morphological features of N49. (1) The western and northern sides should have a semi-circular boundary because, in those directions, interaction with CSM/ISM is much weaker. However, the boundary of N49 is structured, like having two protrusions in the northwest and southwest (marked by 'P' in the upper-left panel of Figure 3). This suggests a non-spherical explosion process. (2) Optical filaments extending from the southeast dense part to the two protrusions on the northwest and southwest. These filaments exist on the far and near side of N49 (Bilikova et al. 2007). An interaction with a cloud on one side cannot explain this large-scale structure of the filaments. (3) Some metals' distribution is along the morphology's dipole line (Zhou et al. 2019). This is most prominent for Ne and Mg, but O and Si also show this asymmetry; S is distributed in the south of N49, and Fe is scattered (Zhou et al. 2019). We present the density and Ne distribution from Zhou et al. (2019) in the lower panels of Figure 3.  \nFrom this short discussion and the similarity to Puppis A, and assuming that the magnetar is not associated with N49, we speculate that the explosion was highly asymmetrical with a strong dipole morphology and that the compact object of N49 has a kick velocity to the northwest, as we mark by the double-line green arrow in the lower left panel of Figure 3 (see Section 5).", '4. HINTS FROM PLANETARY NEBULAE': "The tool of identifying point-symmetrical morphologies and attributing them to jets is prevalent among people studying planetary nebulae (e.g., Sahai et al. 2011, 2024; Clairmont et al. 2022; Danehkar 2022; Moraga Baez et al. 2023; Miranda et al. 2024). We use this tool here.  \nIn Fig. 4, we present Puppis A alongside four planetary nebulae with some, but not full, morphological similarities to Puppis A. The two images of M 1-30 are from Hsia et al. (2014) with the marks from their figures beside the dashed-yellow line. M 1-30 has an enhanced density in the equatorial plane with two lobes on its sides and a prominent pair of ears, aa', and a less prominent pair, bb'. We find a similarity between the pair aa' in M 1-30 and AA ' in Puppis A. The upper right panel is an overexposed image from Hsia et al. (2014) where they  \nidentify a pair of opposite jets (see their marks on the image). The axis of these two jets, the dashed-yellow line that we added on the upper right panel, is perpendicular to the dense strip that Hsia et al. (2014) mark with a dashed-black line (upper middle panel), which we take to be the equatorial plane. We find a similarity between this pair of jets in M 1-30 and the pair BB ' in Puppis A, which is also perpendicular to a dense stripe, more or less the saddle-tongue structure. We mark possible two 'equatorial planes' on the image of Puppis A by dotted-orange lines on the upper left panel of figure 4, one line ending at the P-ear(?) and the other ending at the tongue (see Figure 2 for definitions). A plane somewhere between these two might be considered an 'equatorial plane' only for morphological comparison with planetary nebulae. However, in the case of Puppis A, it is not an equatorial plane of a binary system. The planetary nebula M 1-30 belongs to a class of multipolar planetary nebulae that most researchers attribute to shaping by two or more pairs of jets. We claim the same for Puppis A.  \nIn the lower panels of Figure 4, we present the planetary nebulae A 72, K 3-24, and NGC 650-1 originally from Manchado et al. (1996). The multipolar planetary nebulae K 3-24 and NGC 650-1 exhibit two pairs of ears, which we mark by pairs of light-blue lines and a dense equatorial plane between them (orange-dotted line). These features are also evident in SNR Puppis A, with a bright pair AA ' and two pairs more or less perpendicular to the dense strip, i.e., pairs BB ' and CC ' (for pair CC ' see Figure 1). The morphological similarities between Puppis A and these three planetary nebulae strengthen the claim that Puppis A was also shaped by jets.  \nPuppis A texture is granular; tens of cells (or grains) appear on its surface. Several planetary nebulae have this texture. We present the planetary nebula A 72, which also exhibits granular texture. The similarity of the granular texture suggests that the granular texture is not the result of the explosion process or post-explosion radioactive heating (nickel bubbles). In planetary nebulae, the instability might result in the interaction of the main nebula with a previously ejected CSM or from a fast wind blown by the central star that accelerates the nebula. The same might hold in CCSNRs, where the ejecta interaction with a CSM might lead to granular texture, as the simulations by Orlando et al. (2022) suggest for Cassiopeia A.  \n5. EARLY JET-DRIVEN NS KICK: THE KICK-BEAP MECHANISM  \n<!-- image -->  \n<!-- image -->  \nFigure 3. Images of the SNR N49 emphasizing its large-scale dipole morphology resembling Puppis A. North is up and east to the left. Upper left: HST image (red: H α ; yellow: [S ii ]; blue: [O iii ]; from Bilikova et al. 2007), with our added marks. We point at three out of several filaments extending from the bright southeast side to the west. The letter P refers to the two protrusions. Upper right: A composite image from Ghavam et al. (2024): radio (5.5 GHz ATCA; red), optical (HST; green), and X-ray (Chandra; blue). Lower panels are from Zhou et al. (2019); the dashed circle is the outer boundary for their density calculation. The magnetar is not associated with N49 (see text). Note that the density and Ne distribution share the dipole axis; we mark the dipole axis with a dashed-orange line. The green double-line arrow is our speculation for the kick velocity direction of the NS (not found yet).  \n<!-- image -->  \n8  \n<!-- image -->  \n<!-- image -->  \n<!-- image -->  \n<!-- image -->  \nFigure 4. Comparing the Puppis A's morphology to planetary nebulae. Upper left panel: X-ray image of SNR Puppis A (Credit # : NASA/CXC/IAFE/, Dubner et al. 2013; Arendt et al. 2010; for newer detailed SNR Puppis A morphology features, see Mayer et al. 2022). We added the cyan lines to mark the two pairs of ears AA ' and BB ' (see Figure 1). With dotted orange lines, we mark a plane for comparison with the equatorial plane of the planetary nebulae; one line ends at the P-ear, and the other ends at the tongue (see Figure 1). Upper middle and right panels: Two images of the multipolar planetary nebulae M 1-30 (PN G355 . 9 -04 . 2) and marks from Hsia et al. (2014); we added only the dotted-yellow line that connects the two jets which they marked. The position of the central star is marked with a black cross. We consider the plane that Hsia et al. (2014) marked by a black dotted line the equatorial plane. Hsia et al. (2014) marked the two pairs of ears by aa' and bb'. The lower panels are images of three different planetary nebulae from the IAC morphological catalog of northern Galactic planetary nebulae Manchado et al. 1996 & : PN A 72 (PN G059 . 7 -18 . 7), PN K 3-24 (PN G048 . 7 + 02 . 3), and NGC 650-1 (PN G130 . 9 -10 . 5). In the middle and right lower panels, we added cyan lines to mark pairs of ears and dotted-orange lines to mark a possible equatorial plane of each planetary nebula.  \n<!-- image -->  \n- # https://www.nasa.gov/image-article/unprecedented-x-ray-view-of-supernova-remains/\n- & Images taken from the PNIC catalog Balick 2006: https : // faculty . washington . edu / balick / PNIC /  \nEarlier papers on the natal kick of the NS in the JJEM assumed that the tug-boat mechanism that operates in the delayed neutrino explosion mechanism (e.g., Scheck et al. 2004, 2006; Nordhaus et al. 2010, 2012; Wongwathanarat et al. 2010, 2013; Janka 2017) operates in the JJEM; there are other natal kick mechanisms, e.g., Yamasaki & Foglizzo 2008; Yao et al. 2021; Xu et al. 2022; for general discussion of natal kick velocities see, e.g., Igoshev 2020). We here also take the mechanism of the kick velocity to be hydrodynamical, as evident, for example, from the anti-correlation between the direction of motion of the primary X-ray emitting ejecta and the  \nneutron star observed in Cassiopeia A (e.g., Hwang & Laming 2012).  \nStudies of 14 CCSNe show that the distribution of angles between the jet-main axis in the frame of the JJEM and the NS natal kick avoids small angles (Bear & Soker 2018b, 2023; Soker 2022b). With the tug boat mechanism, this implies that the angle of the main-jet axis to the dense clump that accelerates the NS avoids small angles. The first possible explanation holds that the jets prevent the formation of dense clumps along their propagation directions, and therefore, no NS acceleration takes place in those directions. The second expla-  \n<!-- image -->  \nnation has several dense clumps that are falling towards the NS. Some clumps feed an accretion disk around the NS, and some escape and accelerate the NS by pulling it. This accretion disk launches jets along the angular momentum axis, perpendicular to the direction of the clumps' inflow, hence to the kick velocity.  \nThe gravitational tug-boat mechanism operates for a relatively long time of several or more seconds. It converts the internal energy of the ejecta into kinetic energy of the ejecta, maintaining shell expansion (Wongwathanarat et al. 2013). Below, we suggest a very short mechanism to give the NS a kick velocity early in the explosion process. The tug-boat mechanism can operate later as well.  \nThe characteristic lifetime of an intermittent accretion disk that launches a pair of jets in the JJEM is ≃ 0 . 01 -0 . 3 s (e.g., Soker 2024a), a time scale that is about equal or shorter than the viscous timescale of the accretion disk, which is its relaxation timescale (e.g., Soker 2024a). The implication is that the accretion disk has no time to fully relax. Considering that the gas that feeds the accretion disk has large fluctuations in its properties, the two sides of the accretion disk are born unequal and have no time to relax. Such a disk will likely launch two opposite jets unequal in power and opening angle (Soker 2024b).  \nConsider the very early time after the shock bounces and stalls at r ≃ 100 -150 km s -1 . At the period of t b ≲ 0 . 2 s, where t b is the time measured from shock bounce, the mass accretion rate onto the very young central object, a bloated NS star, is ˙ M acc ≳ 1 M ⊙ s -1 (e.g., Muller et al. 2017; Burrows et al. 2024a). Due to its still lower mass and large radius, the escape velocity from the NS is lower than at the later phases of the explosion process, and we scale the jets' velocity by v j = 5 × 10 4 km s -1 ; this is an expected minimum velocity, as it might be somewhat larger, up to ≃ 10 5 km s -1 . Consider a short accretion period through an accretion disk that lives for ∆ t 1 ≃ 0 . 05 s. As discussed above, the disk doesn't have time to relax, and one jet can be much more powerful than the counter jet. We assume the more powerful jet carries much more momentum than the counter jet. This one jet carries a fraction f j1 ≃ 0 . 1 of the accreted mass, while the counter jet carries a fraction f j2 ≪ f j1 . The momentum and energy of the pair of jets are  \np j12 = 250 ( f j1 -f j2 0 . 1 )( ∆ t 1 0 . 05 s ) ( ˙ M acc 1 M ⊙ s -1 ) × ( v j 5 × 10 4 km s -1 ) M ⊙ km s -1 , (1)  \nand  \nE j12 = 1 . 24 × 10 50 ( f j1 + f j2 0 . 1 )( ∆ t 1 0 . 05 s ) × ( ˙ M acc 1 M ⊙ s -1 ) ( v j 5 × 10 4 km s -1 ) 2 erg , (2)  \nrespectively.  \nThe observed NS kick velocity distribution ranges from very slow to v NS ≃ 1000 km s -1 , with two peaks at ≃ 80 km s -1 and ≃ 500 km s -1 (e.g., Igoshev 2020). For a typical NS mass of M NS = 1 . 4 M ⊙ the momenta of most NSs are in the range p NS ≃ 100 -700 M ⊙ km s -1 . The highly asymmetrical and powerful jet pair at a very early time can account for this natal kick; we term it the kick by early asymmetrical pairs (Kick-BEAP) mechanism. The tug-boat mechanism can act later and change the value of the kick velocity that the kick-BEAP mechanism imparted.  \nOur suggested kick-BEAP mechanism imparts a large natal kick velocity to the NS at the beginning of the explosion process before the NS launches most jittering jets and therefore has the following properties and consequences.  \n- 1. There might be two or even three pairs of jets that can impart large kick velocity at t b ≲ 0 . 2 s.\n- 2. Because the core is still intact, the strong early jets can lead to the nucleosynthesis of elements from silicon to iron group with high asymmetrical distribution in the opposite direction to the natal kick velocity. This is the focus of a future study.\n- 3. For the same reason, these early jets will all be choked inside the core and will not shape ears and bubbles in the CCSNR. Their marks are the kick velocity and the asymmetrical ejecta of some elements.\n- 4. The NS launches the later jets, including the last pairs of jets with large marks on the CCSNR morphology, while it is already moving relative to the center of the collapsing core. This can explain the avoidance of small angles between the main jet axis and the kick velocity. We elaborate on this below.  \nConsider then that after the kick-BEAP phase, at t b ≳ 0 . 2 s, the NS moves at a velocity of v NS ≈ 50 -500 km s -1 relative to the center of mass of the pre-collapse core. We are interested in the final energetic pair of jets, the pair that is likely to shape the main jet axis (Soker 2024a). The mass that the NS accretes at the final accretion phases of the explosion  \nprocess, about a second to a few after the shock bounce, originates from a radius of r f ≃ 3000 km (e.g., Shishkin & Soker 2021). The impact parameter, namely the distance of the accreted mass from the trajectory of the NS, is in the range 0 ≤ b ≤ r f . The specific angular moment that the kick velocity adds to an accreted parcel of gas with an impact parameter b is perpendicular to the kick velocity with a magnitude of  \nj k = 3 . 75 × 10 15 ( b 1500 km ) ( v NS 250 km s -1 ) cm 2 s -1 . (3)  \nThis value is of the order of magnitude of the specific angular momentum fluctuations in the core convective zones (e.g., Shishkin & Soker 2021, 2022). Therefore, ⃗ j k that is perpendicular to ⃗v NS prevents small angles between the kick velocity and the jet-main axis, and explains this finding (e.g., Bear & Soker 2023).", '6. SUMMARY': "We revealed a point-symmetric structure of three pairs of ears in the CCSNR Puppis A (Figure 1). The centers of the three symmetry lines that connect the two ears of each pair are within the general region between the present location of the NS remnant and its calculated location at the explosion time. Like with other CCSNRs with point-symmetric morphologies (Section 1), the point-symmetric morphology strongly suggests explosion by jittering jets, i.e., the JJEM; other shaping processes, like instabilities, interaction with a CSM and with the ISM, cannot account for the observed point-symmetric morphologies of CCSNRs (e.g., Soker & Shishkin 2024). In Section 4, we compared the pointsymmetric morphology of Puppis A with three multipolar planetary nebulae that researchers consider to have been shaped by two or more pairs of jets. The similarities between Puppis A's point-symmetric morphology and the three planetary nebulae (Figure 4) further solidify our claim that energetic jets shaped the pointsymmetric morphology of Puppis A. According to the JJEM, these jets are part of ≈ 10 -30 pairs of jets that exploded the progenitor of Puppis A.  \nThe elongated morphological features of the 'corridor' and the line connecting the ejecta-rich clump with the 'tongue' (dashed lines on Figure 2) require deeper observations and analysis to explore their properties and whether jets also shaped their structures.  \nIn this study, we also focused on the solid dipole structure of Puppis A. Its prominent components are the Xray and radio bright 'saddle' with a sharp edge on the northeast and the much fainter and diffuse other side. A possible ear, the P-ear(?), and the tongue (Figure 2) are the prominent components of the other dipole side of  \nthe saddle. We notice a similar, but not identical, dipole structure in the SNR N49 (Section 3). In N49, filaments extend from the bright side of the dipole to its fainter opposite side (Figure 3). The filaments in N49 and the corridor in Puppis A that extend from one side to the other imply that an internal process shaped the dipole structures. A CSM or an ISM cloud on the dense side of an SNR can compress that side but cannot form filaments and structures extending to the other side. Also, the NS kick velocity in Puppis A is opposite to the side of the dense part, the saddle (Figure 2).  \nBased on the dipole structure of Puppis A and its relation to the kick velocity direction, we proposed (Section 5) a mechanism in the frame of the JJEM to impart a natal kick to the NS. In this kick-BEAP (kick by early asymmetrical pair) mechanism, the very young NS, age of ≲ 0 . 2 s, launches a pair of jets where one jet is much more energetic than the counter jet. This takes place when the accretion rate is very high. Momentum conservation implies that the NS recoils in the opposite direction of the much more energetic jets. Such highly unequal jets in a pair in many, but not all, cases is one of the expectations of the JJEM (Soker 2024b). The more energetic jet in the pair compresses a dense side to the SNR while the NS acquires a natal kick velocity in the opposite direction. The kick-BEAP mechanism allows for the tug-boat mechanism, which occurs at a little later time in the explosion, to operate as well, but it is not necessary as the kick-BEAP might account for a large range of kick velocities (equation 1).  \nOur study further supports the JJEM as the primary, or even sole, explosion mechanism of CCSNe and adds to the role of jets by introducing the novel kick-BEAP mechanism.", 'ACKNOWLEDGEMENTS': "A grant from the Pazy Foundation supported this research.  \nWe thank Martin Mayer for advice regarding eROSITA data and useful comments.  \nWe acknowledge the use of NASA's SkyView facility (https://skyview.gsfc.nasa.gov) located at NASA Goddard Space Flight Center.  \nThis work made use of Astropy: 1 a communitydeveloped core Python package and an ecosystem of tools and resources for astronomy (Astropy Collaboration et al. 2013, 2018, 2022).  \nThis work makes use of data from eROSITA, the soft X-ray instrument aboard SRG, a joint Russian-German  \nscience mission supported by the Russian Space Agency (Roskosmos), in the interests of the Russian Academy of Sciences represented by its Space Research Institute (IKI), and the Deutsches Zentrum fur Luft- und Raumfahrt (DLR). The SRG spacecraft was built by Lavochkin Association (NPOL) and its subcontractors, and is operated by NPOL with support from the Max Planck Institute for Extraterrestrial Physics (MPE). The development and construction of the eROSITA X-ray instrument was led by MPE, with contributions from the Dr. Karl Remeis Observatory Bamberg & ECAP (FAU Erlangen-Nuernberg), the University of Hamburg Observatory, the Leibniz Institute for Astrophysics Potsdam (AIP), and the Institute for Astronomy and Astrophysics of the University of Tubingen, with the support of DLR and the Max Planck Society. The Argelander  \nInstitute for Astronomy of the University of Bonn and the Ludwig Maximilians Universitat Munich also participated in the science preparation for eROSITA.  \nThis publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.  \nWe used the PNIC: Planetary Nebula Image Catalogue composed by Bruce Balick (http://faculty.washington.edu/balick/PNIC/)  \nSoftware: Astropy (Astropy Collaboration et al. 2013, 2018, 2022), Matplotlib (Hunter 2007), NumPy (Harris et al. 2020)", 'REFERENCES': '- Wang, N. Y. 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