arXiv subjects

Noam Soker

Publications and source records attributed to Noam Soker.

At least 109 records · Page 6Linked to original sources

arXiv2023

The depletion of the red supergiant envelope radiative zone during common envelope evolution

We conduct one-dimensional stellar evolution simulations of red supergiant (RSG) stars that mimic common envelope evolution (CEE) and find that the inner boundary of the envelope convective zone moves into the initial envelope radiative zone. The envelope convection practically disappears only when the RSG radius decreases by about an order of magnitude or more. The implication is that one cannot split the CEE into one stage during which the companion spirals-in inside the envelope convective zone and removes it, and a second slower phase when the companion orbits the initial envelope radiative zone and a stable mass transfer takes place. At best, this might take place when the orbital separation is about several solar radii. However, by that time other processes become important. We conclude that as of yet, the commonly used alpha-formalism that is based on energy considerations is the best phenomenological formalism.

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arXiv2023

Terminating a common envelope jets supernova impostor event with a super-Eddington blue supergiant

We conducted one-dimensional stellar evolutionary numerical simulations to build blue supergiant stellar models with a very low-envelope mass and a super-Eddington luminosity of 10^7Lo that mimic the last phase of a common envelope evolution (CEE) where a neutron star (NS) accretes mass from the envelope and launches jets that power the system. Common envelope jets supernovae (CEJSNe) are CEE transient events where a NS spirals-in inside the envelope and then the core of a red supergiant (RSG) star accretes mass and launches jets that power the transient event. In case that the NS (or black hole) does not enter the core of the RSG the event is a CEJSN-impostor. We propose that in some cases a CEJSN-impostor event might end with such a phase of a blue supergiant lasting for several years to few tens of years. The radius of the blue supergiant is about tens to few hundreds solar radii. We use a simple prescription to deposit the jets energy into the envelope. We find that the expected accretion rate of envelope mass onto the NS at the end of the CEE allows the power of the jets to be as we assume, 10^7Lo. Such a low-mass envelope might be the end of the RSG envelope, or might be a rebuilt envelope from mass fallback. Our study of a blue supergiant at the termination of a CEJSN-impostor event adds to the rich variety of transients that CEJSNe and CEJSN-impostors might form.

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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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arXiv2023

The core degenerate scenario for the type Ia supernova SN 2020eyj

We argue that the core degenerate (CD) scenario of type Ia supernovae (SNe Ia) can explain the compact helium-rich circumstellar material (CSM) of SN 2020eyj. In the new channel of the CD scenario that we propose there are two major common envelope evolution (CEE) phases. After the white dwarf (WD) companion removes the hydrogen-rich envelope of the asymptotic giant branch star its spiralling-in halts at few solar radii from the core, rather than continuing to the carbon-oxygen (CO) core as in the hydrogen-rich SNe Ia-CSM CD scenario. Only hundreds to tens of thousands of years later, after the helium-rich core expands, does the WD enters a CEE with the helium-rich layer. By that time the hydrogen-rich envelope is at a large distance from the center. The WD merges with the CO core during the second CEE phase, and only after a merger to explosion delay (MED) time of weeks to tens of years the merger remnant explodes. The SN Ia ejecta collides with a helium-rich CSM at tens to hundreds of AU. We follow the evolution of two stellar models with initial masses of 5Mo and 7Mo to their asymptotic giant branch phase when they are supposed to engulf the WD companion. We find that there is a sufficiently massive CO core to merge with the WD in the frame of the CD scenario as well as a massive helium-rich layer, ~0.3-1Mo, to account for the helium-rich CSM of SN 2020eyj.

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arXiv2023

Simulating the deposition of angular momentum by jets in common envelope evolution

We conducted three-dimensional hydrodynamical simulations of common envelope evolution (CEE) of a neutron star (NS) or a black hole (BH) inside a red supergiant (RSG) envelope and find that the jets that we expect the NS/BH to launch during the CEE spin-up the common envelope. We find that when the NS/BH launches jets that are exactly perpendicular to the orbital plane (the jets are aligned with the orbital angular momentum) the jets deposit angular momentum to the envelope that is aligned with the orbital angular momentum. When the jets' axis is inclined to the orbital angular momentum axis so is the angular momentum that the jets deposit to the envelope. Such tilted jets might be launched when the NS/BH has a close companion when it enters the RSG envelope. We did not allow for spiralling-in and could follow the evolution for only three orbits. The first orbit mimics the plunge-in phase of the CEE, when the NS/BH rapidly dives in, while the third orbit mimics the self-regulated phase when spiralling-in is very slow. We find that the jets deposit significant amount of angular momentum only during the plunge-in phase. A post-CEE core collapse supernova explosion will leave two NS/BH, bound or unbound, whose spin might be misaligned to the orbital angular momentum. Our results strengthen an earlier claim that inclined-triple-star CEE might lead to spin-orbit misalignment of NS/BH-NS/BH binary systems.

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arXiv2023

Implications of post-kick jets in core collapse supernovae

I examine the assumption that the jets that shape the axisymmetrical morphological features of core collapse supernova (CCSN) remnants are post-kick jets, i.e., the neutron star (NS) launches these jets after the explosion and after it acquired its natal kick velocity. I find that this assumption implies that the pre-collapse cores of CCSN progenitors have sufficient angular momentum fluctuations to support jittering jets that explode the star. From the finding that the shaping-jets neither tend to be aligned with the kick velocity nor to be perpendicular to it I argue that the assumption that the shaping-jets are post-kick jets has the following implications. (1) The NS accretes mass at a radius of ~5000km from the center of the explosion at ~10 s after explosion. (2) The required angular momentum fluctuations of the accreted gas to explain the medium values of jets-kick angles are also sufficient to support an intermittent pre-kick accretion disk, just before and during the explosion. Such an intermittent accretion disk is likely to launch jets that explode the star in the frame of the jittering jets explosion mechanism. This suggests that most likely the shaping-jets are the last jets in the jittering jets explosion mechanism rather than post-kick jets. (3) The jittering jets explosion mechanism expects that black holes have small natal kick velocities.

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arXiv2023

The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

Planetary nebulae (PNe), the ejected envelopes of red giant stars, provide us with a history of the last, mass-losing phases of 90 percent of stars initially more massive than the Sun. Here, we analyse James Webb Space Telescope (JWST) Early Release Observation (ERO) images of the PN NGC3132. A structured, extended H2 halo surrounding an ionised central bubble is imprinted with spiral structures, likely shaped by a low-mass companion orbiting the central star at 40-60 AU. The images also reveal a mid-IR excess at the central star interpreted as a dusty disk, indicative of an interaction with another, closer companion. Including the previously known, A-type visual companion, the progenitor of the NGC3132 PN must have been at least a stellar quartet. The JWST images allow us to generate a model of the illumination, ionisation and hydrodynamics of the molecular halo, demonstrating the power of JWST to investigate complex stellar outflows. Further, new measurements of the A-type visual companion allow us to derive the value for the mass of the progenitor of a central star to date with excellent precision: 2.86+/-0.06 Mo. These results serve as path finders for future JWST observations of PNe providing unique insight into fundamental astrophysical processes including colliding winds, and binary star interactions, with implications for supernovae and gravitational wave systems.

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arXiv2022

The role of jets in exploding supernovae and in shaping their remnants

I review studies of core collapse supernovae (CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosion mechanism that I take to power most CCSN explosions. Neutrino heating does play a role in boosting the jets. I compare the morphologies of some CCSN remnants to planetary nebulae to conclude that jets and instabilities are behind the shaping of their ejecta. I then discuss CCSNe that are descendants of rapidly rotating collapsing cores that result in fixed-axis jets (with small jittering) that shape bipolar ejecta. A large fraction of the bipolar CCSNe are superluminous supernovae (SLSNe). I conclude that modelling of SLSNe lightcurves and bumps in the lightcurves must include jets, even when considering energetic magnetars and/or ejecta interaction with the circumstellar matter (CSM). I connect the properties of bipolar CCSNe to common envelope jets supernovae (CEJSNe) where an old neutron star or a black hole spirals-in inside the envelope and then inside the core of a red supergiant. I discuss how jets can shape the pre-explosion CSM, as in supernova 1987A, and can power pre-explosion outbursts (precursors) in binary systems progenitors of CCSNe and CEJSNe. Binary interaction facilitate also the launching of post-explosion jets.

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arXiv2022

Rapid decline in the lightcurves of luminous supernovae by jet-driven bipolar explosions

We calculate the lightcurves of jet-driven bipolar core collapse supernova (CCSN) explosions into a bipolar circumstellar mater (CSM) and show that an equatorial observer finds the lightcurves to possess a rapid, and even an abrupt, drop. The scenario that might lead to such an explosion morphology is a common envelope evolution (CEE) where shortly before the CCSN explosion the RSG progenitor interacts with a more compact companion that spirals-in and spins-up the core. The companion can be a main sequence star, a neutron star, or a black hole. The binary interaction ejects a shell through an intensive wind and the CEE ejects a denser gas in the equatorial plane. We assume that the companion accretes mass and launches jets. We conduct three-dimensional (3D) hydrodynamical simulations where we launch weak jets, the shaping jets, into the dense shell and show that the interaction forms a bipolar CSM. As a result of the rapid pre-collapse core rotation jets drive the CCSN explosion. We simulate the interaction of the jets with the bipolar CSM and use a simple scheme to calculate the lightcurves. We show that the abrupt drop in the lightcurve of an observer not too close to the polar directions can account for the lightcurve of the hydrogen poor luminous supernova (LSN) SN 2018don. Our study strengthens the claim that jet-driven explosions account for many, even most, CCSNe.

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arXiv2022

Pre-explosion, explosion, and post-explosion jets in supernova SN 2019zrk

I analyse some properties of the luminous transient event SN 2019zrk and conclude that jets were the main powering sources of the pre-explosion outburst (precursor) and ejection of a massive circumstellar matter (CSM), of the very energetic explosion itself, and of the post-explosion bump in the light curve. The pre-explosion energy source is mainly a companion (main sequence, Wolf-Rayet, neutron star or black hole) star that accreted mass and launched jets. I find that the fast expansion of the CSM after acceleration by the explosion ejecta requires the explosion energy to be >10^{52} erg. Only jet-driven explosions can supply this energy in such SN 2009ip-like transients. I conclude that ejecta-CSM interaction is extremely unlikely to power the bright bump at about 110 days after explosion. Instead, I show by applying a jet-driven bump toy-model that post-explosion jets are the most likely explanation for the bump. I leave open the question of whether the explosion itself (main outburst) was a core collapse supernova (CCSN) or a common envelope jets supernova (CEJSN). In this study I further connect peculiar transient events, here 2009ip-like transient events, to CCSNe by arguing that jets drive all events, from regular CCSNe through superluminous CCSNe and to many other peculiar and super-energetic transient events, including CEJSNe. Jet-powering cannot be ignored when analyzing all these types of transients.

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arXiv2022

Jittering jets by negative angular momentum feedback in cooling flows

I apply the jittering jets in cooling flow scenario to explain the perpendicular to each other and almost coeval two pairs of bubbles in the cooling flow galaxy cluster RBS 797, and conclude that the interaction of the jets with the cold dense clumps that feed the supermassive black hole (SMBH) takes place in the zone where the gravitational influence of the SMBH and that of the cluster are about equal. According to the jittering jets in cooling flow scenario jets uplift and entrain cold and dense clumps, impart the clumps velocity perpendicular to the original jets' direction, and `drop' them closer to the jets' axis. The angular momentum of these clumps is at a very high angle to the original jets' axis. When these clumps feed the SMBH in the next outburst (jet-launching episode) the new jets' axis might be at a high angle to the axis of the first pair of jets. I apply this scenario to recent observations that show the two perpendicular pairs of bubbles in RBS 797 to have a small age difference of <10Myr, and conclude that the jets-clumps interaction takes place in a distance of about 10-100 pc from the SMBH. Interestingly, in this zone the escape velocity from the SMBH is about equal to the sound speed of the intracluster medium (ICM). I mention two other clusters of galaxies and discuss the implications of this finding.

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arXiv2022

Feeding post core collapse supernova explosion jets with an inflated main sequence companion

We simulate the response of a main sequence star to the explosion of a stripped-envelope (type Ib or Ic) core collapse supernova (CCSN) when the main sequence star orbits the core at a distance of 10-20Ro at explosion. We use the stellar evolution code MESA to follow the response of main sequence stars of masses 3Mo and 7Mo to energy deposition and mass removal. The collision of the CCSN ejecta with the main sequence star deposits energy and inflate the main sequence star. If the binary system stays bound after the CCSN explosion the inflated main sequence star might engulf the newly born neutron star (NS). We assume that the NS accretes mass through an accretion disk and launches jets. The jets remove mass from the inflated main sequence star and collide with the CCSN ejecta. Although this scenario is rare, it adds up to other rare scenarios to further support the notion that many stripped envelope CCSNe are powered by late jets. The late jets can power these CCSNe-I for a long time and might power bumps in their lightcurve. The jets might also shape the inner ejecta to a bipolar morphology. Our results further support suggestions that there are several ways to feed a NS (or a black hole) to launch the late jets in superluminous supernovae.

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arXiv2022

The response of a red supergiant to a common envelope jets supernova (CEJSN) impostor event

Using a one-dimensional stellar evolution code we simulate the response of a red supergiant (RSG) star to injection of energy and to mass removal. We take the values of the energy that we inject and the mass that we remove according to our previous three-dimensional hydrodynamical simulations of a neutron star (NS) on a highly eccentric orbit that enters the envelope of an RSG star for half a year and launches jets as it accretes mass via an accretion disk. We find that for injected energies of ~1e47-1e48 erg and removed mass of ~0.03-0.6Mo the RSG envelope expands to a large radius. Therefore, we expect the NS to continue to orbit inside this massive inflated envelope for several more months, up to about twice the initial RSG radius, to continue to accrete mass and launch jets for a prolonged period. Although these late jets are weaker than the jets that the NS launches while inside the original RSG envelope, the late jets might actually be more influential on the light curve, leading to a long, several months to few years, and bright, about >10^8Lo, transient event. The RSG returns to more or less a relaxed structure after about ten years, and so another transient event might occur in the next periastron passage of the NS. Our results add to the already rich variety of jet-driven explosions/outbursts that might account for many puzzling transient events.

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arXiv2022

Onset of common envelope evolution during a core helium flash by rapid envelope expansion

We suggest that the vigorous core convection during core helium flash on the tip of the red giant branch (RGB) of low mass stars excites waves that carry energy to the envelope and inflate it for few years to increase the number of extreme horizontal branch (EHB; sdB and sdO) stars with masses of ~0.47Mo with respect to canonical binary evolution. Using the open-source MESA-binary we follow the evolution of a number of eccentric binary systems with an initial primary stellar mass of 1.6Mo. The energy that the waves carry to the envelope leads to envelope expansion at the tip of the RGB. The inflated RGB star engulfs many secondary stars to start a CEE that otherwise would not occur. If the secondary star manages to remove most of the RGB envelope the primary evolves to become an EHB star with a mass of ~0.47Mo. However, we expect that in most cases the secondary star does not have time to spiral-in to close orbits. It rather ends at a large orbit and leaves a massive enough envelope for the primary star to later evolve along the asymptotic giant branch and to engulf the secondary star, therefore forming a non-spherical planetary nebula.

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arXiv2022

Powering luminous core collapse supernovae with jets

I examine recent fittings of luminous supernovae (LSNe) with extra energy sources of magnetar and helium burning and find that in about half of these LSNe the fitting parameters have some problems. In some LSNe the total energy of these two energy sources is larger than the kinetic energy of the ejecta that the fitting yields. In some others LSNe the total energy of the delayed neutrino explosion mechanism and these two extra sources combined is smaller than the kinetic energy that the fitting yields. These difficulties suggest that, like earlier claims that jets power superluminous supernovae (SLSNe), jets also power the less luminous LSNe. A magnetar might also supply energy. However, in most cases jets supply more energy than the magnetar, during the explosion and possibly at late times. I strengthen an earlier claim that jets launched at magnetar birth cannot be ignored. I explain the trend of maximum rise time for a given luminosity of hydrogen deficient core collapse supernovae (CCSNe), in particular LSNe and SLSNe, with a toy model of jets that are active for a long time after explosion.

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arXiv2022

Pre-explosion helium shell flash in type Ia supernovae

I study the possibility that within the frame of the core degenerate (CD) scenario for type Ia supernovae (SNe Ia) the merger process of the core of the asymptotic giant branch (AGB) star and the white dwarf (WD) maintains an envelope mass of ~0.03Mo that causes a later helium shell flash. I estimate the number of pre-explosion helium shell flash events to be less than few per cents of all CD scenario SNe Ia. A helium shell flash while the star moves to the left on the HR diagram as a post-AGB star (late thermal pulse; LTP) or along the WD cooling track (very LTP) causes the star to expand and become a born again AGB star. Merger remnants exploding while still on the AGB form {hydrogen-polluted} peculiar SNe Ia, while an explosion inside an inflated born-again star results in an early flux excess in the light curve of the SN Ia. The fraction of systems that might show an early flux excess due to LTP/VLTP is <(few)x10^{-4} of all SNe Ia, much below the observed fraction. In the frame of the CD scenario SNe Ia with early flux excess result from SN ejecta collision with planetary nebula fallback gas, or from mixing of 56Ni to the outer regions of the SN ejecta. Ongoing sky surveys might find about one case per year where LTP/VLTP influences the SN light curve.

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arXiv2022

Boosting jittering jets by neutrino heating in core collapse supernovae

I estimate the energy that neutrino heating adds to the outflow that jets induce in the collapsing core material in core collapse supernovae (CCSNe), and find that this energy crudely doubles the energy that the jets deposit into the outer core. I consider the jittering jets explosion mechanism where there are several stochastic jet-launching episodes, each lasting for about 0.01-0.1 seconds. The collapsing core material passes through the stalled shock at about 100 km and then slowly flows onto the proto-neutron star (NS). I assume that the proto-NS launches jittering jets, and that the jets break out from the stalled shock. I examine the boosting process by which the high-pressure gas inside the stalled shock, the gain region material, expands alongside the jets and does work on the material that the jets shock, the cocoon. This work is crudely equal to the energy that the original jets carry. I argue that the coupling between instabilities, stochastic rotation, magnetic fields, and jittering jets lead to most CCSN explosions. In other cases, the pre-collapse core is rapidly rotating and therefore ordered rotation replaces stochastic rotation and fixed jets replace jittering jets.

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arXiv2022

A rapidly fading star as a type II obscuring intermediate luminosity optical transient (ILOT) in a triple star system

We propose a triple-star scenario where the merger of two pre-main sequence low mass stars, <0.5Mo, ejects a dusty equatorial outflow that obscures and temporarily causes the disappearance of a massive star, >8Mo. The merger of the low-mass inner binary powers a faint outburst, i.e., a faint intermediate luminosity optical transient (ILOT), but its main effect that can last for decades is to (almost) disappear the luminous massive star of the triple system. The typical orbital period of the triple system in about a year. The merger process proceeds as the more massive star of the two low-mass pre-main sequence star starts to transfer mass to the least massive star in the triple system and as a result of that expands. This 'type II obscuring ILOT' scenario in a triple star system might account for the fading, re-brightening, and then re-fading of the massive post-main sequence star M101-OC1. It might recover in about 20-100 year. Our study strengthens the claim that there are alternative scenarios to account for the (almost) disappearing of massive stars, removing the need for failed supernovae. In these scenarios the disappearing is temporary, months to decades, and therefore at later time the massive star explodes as a core collapse supernova even if it forms a black hole.

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