core collapse

Top PDF core collapse:

Neutrino nucleosynthesis in core-collapse Supernova explosions

Neutrino nucleosynthesis in core-collapse Supernova explosions

Core-Collapse-Supernova explosions are among the most energetic events known to astronomers and mark the end of the live of massive stars. The conditions created by the passage of the supernova shockwave through the chemically enriched layers of massive stars allow for important nucleosynthe- sis processes to occur which are crucial for the enrichment of the interstellar medium and chemical evolution of the universe. A major part of the energy released by the core-collapse leaves the stellar core in the form of neutrinos of all flavors.

6 Read more

First targeted search for gravitational-wave bursts from core-collapse supernovae in data of first-generation laser interferometer detectors

First targeted search for gravitational-wave bursts from core-collapse supernovae in data of first-generation laser interferometer detectors

SN 2008bk, a type-IIP supernova, was discovered on 2008 March 25.14 UTC [107]. Its explosion time is poorly constrained by a pre-explosion image taken on 2008 January 2.74 UTC [107]. Morrell and Stritzinger [108] compared a spectrum taken of SN 2008bk on 2008 April 12.4 UTC to a library of SN spectra [109] and found a best fit to the spectrum of SN 1999em taken at 36 days after explosion [108]. However, the next other spectra available for SN 1999em are from 20 and 75 days after explosion, so the uncertainty of this result is rather large. EPM modeling by Dessart [110] suggests an explosion time of March 19 . 5 5 UTC, which is broadly consistent with the light- curve data and hydrodynamical modeling presented in Ref. [111]. The progenitor of SN 2008bk was most likely a red supergiant with a radius of ∼500 R ⊙ [112 – 114], which suggests an explosion time of ∼1 day after core collapse [8 – 10]. Hence, we assume a conservative on-source win- dow of 2008 March 13.5 UTC to 2008 March 25.14 UTC. The coordinates of SN 2008bk are R:A: ¼ 23 h 57 m 50 s .42, Decl ¼ −32 ° 33 0 21″ . 5 [115]. Its host galaxy is NGC 7793, which is located at a Cepheid distance D ¼ ð3 . 44 þ 0 . 21 − 0 . 2Þ Mpc [116]. This distance esti- mate is consistent with D ¼ ð3 . 61 þ 0 . 13 − 0 . 14Þ Mpc obtained by Ref. [117] based on the tip of the red-giant branch method (e.g., Ref. [118]). For the purpose of this study, we use a conservative averaged estimate of D ¼ ð3 . 53 þ 0 . 21 − 0 . 29Þ Mpc.
Show more

25 Read more

Neutrino-Induced Nucleosynthesis in Helium Shells of Early Core-Collapse Supernovae

Neutrino-Induced Nucleosynthesis in Helium Shells of Early Core-Collapse Supernovae

Observations of the chemical composition in metal-poor stars provide important clues for the source of metal enrichment in the early Galaxy. In this regard, extremely metal-poor (EMP) stars with [Fe / H] ≡ log(Fe / H) − log(Fe / H) − 2 . 5 are especially useful as they sample gases polluted by just a few nucleosynthetic events. With a growing number of observational studies on EMP stars, it has now become clear that neutron-capture elements were present in the early Galaxy, where only stars more massive than ∼ 8 M that end their lives as core-collapse supernovae (CCSNe) could have con- tributed [1]. The abundance patterns observed in EMP stars show large variations. Some stars have abundance patterns similar to the solar rapid neutron-capture (r) process distribution and others have patterns similar to the slow neutron-capture ( s) process distribution or to a mixture of r and s process distributions [2]. This suggests a variety of neutron-capture processes operated in the early Galaxy. EMP stars with s-process signatures are thought to have experienced surface pollution by a binary
Show more

6 Read more

Significance of neutrino-neutrino interaction in neutrino oscillation in core-collapse supernova

Significance of neutrino-neutrino interaction in neutrino oscillation in core-collapse supernova

Figure 1 and 2 shows the variation of distance K with interaction angle. This variation shows the − oscillation probabilities, as a function of the distance in supernova. The graphs obtained clearly indicate strong − interaction at cos b FG' = 0 i.e. b FG' = 2 ⁄ where the length of interaction is equals to . The possibility of − interaction in the range K → shows the probability of − oscillation in the dense core of SN. If the value of cos b FG' is altered, then we see the length of interaction increases exponentially, and hence the − oscillation due to − interaction will be rare. Also when the angle of interaction is about 25˚ or 155˚, the graph indicates free streaming of neutrinos in the form of shock waves. Some of the recent study of core collapse supernovae justifies the above conclusion.
Show more

7 Read more

Core-Collapse Supernova neutrino detection prospects with the KM3NeT neutrino telescopes.

Core-Collapse Supernova neutrino detection prospects with the KM3NeT neutrino telescopes.

Abstract. Core Collapse Supernovae (CCSN) are explosive phenomena that may occur at the end of the life of massive stars, releasing over 99% of the energy through neutrino emission with energies on the 10 MeV scale. While the explosion mechanism is not fully understood, neutrinos are believed to play an important role. The only detection as of today are the 24 neutrinos from supernova SN1987A. The observation of the next Galactic CCSN will lead to important breakthroughs across the fields of astrophysics, nuclear and particle physics.

5 Read more

Modeling Rapidly Fading Supernovae as Nickel Free Core Collapse Explosions of Extended Helium Stars

Modeling Rapidly Fading Supernovae as Nickel Free Core Collapse Explosions of Extended Helium Stars

a protostellar cloud that happens to have a large angular momentum. Rotation can introduce additional mixing that is not typically incorporated into stellar models; for example, rotationally induced mixing similar to meteorological turbulence on Earth could cause a star to entirely dredge up nuclear burning products from its core to the surface on the Main Sequence, immediately producing a fully H-free star without any significant mass loss (Maeder 1987), which is expected to evolve blueward on the HR diagram. Rotationally mixed stars have been invoked as potential GRB progenitors (Kulkarni et al. 1998; Woosley et al. 1999; Fryer & Heger 2005; Yoon & Langer 2005; Yoon et al. 2006) since they could become H-free without spinning down and losing angular momentum during Roche lobe overflow in a binary system. They have also been proposed as the progenitors of single or binary black hole systems should the core collapse (Mandel & de Mink 2016). Brott et al. (2011) present a grid of models of such stars and show this blueward evolution. Therefore it may be possible through rotation alone to produce progenitors for H-free SNe without strong radiation-driven winds or binary evolution. What these stars will look like prior to core collapse is uncertain, but these rotating stars should be investigated further as potential progenitors for a variety of H-free explosions. One might expect, however, that stars with large amounts of angular momentum would not be attractive candidates for SNe that undergo nickel fallback, which may be required to produce RFSNe. Nevertheless, they should result in some kind of exotic transient.
Show more

147 Read more

Multipole Analysis of Radio Continuum Images of Supernova Remnants: Comparison of Type Ia and Core Collapse

Multipole Analysis of Radio Continuum Images of Supernova Remnants: Comparison of Type Ia and Core Collapse

A multipole expansion analysis is applied to 1420 MHz radio continuum im- ages of supernova remnants (SNRs) in order to compare Type Ia and core collapse (CC) SNRs. Because the radio synchrotron emission is produced at the outer shock between the SNR and the ISM, we are investigating whether the ISM interaction of SNRs is different between Type Ia and CC SNRs. This is in contrast to previous investigations, which have shown that Type Ia and CC SNRs have different asymmetries in the X-ray emission from their ejecta. The sample consists of 19 SNRs which have been classified as either Type Ia or CC. The quadrupole and octupole moments normalized to their monopole moments (total emission) are used as a measure of asymmetry of the emis- sion. A broad range (by a factor of ~1000) is found for both quadrupole and octupole normalized moments. The strongest correlation we find is that large quadrupole moments are associated with large octupole moments, indicating that both serve as similar indicators of asymmetry. The other correlation we find is that both moments increase with SNR age or radius. This indicates that interstellar medium structure is a strong contributor to asymmetries in the radio emission from SNRs. This does not seem to apply to molecular clouds, because we find that association of a SNR with a molecular cloud is not correlated with larger quadrupole or octupole moments.
Show more

13 Read more

Acoustic Wave Dynamics in the Post-Bounce Phase of Core Collapse Supernovae

Acoustic Wave Dynamics in the Post-Bounce Phase of Core Collapse Supernovae

How a core collapse supernova successfully “explodes” is only partially understood. A star, for the majority of its life, resists collapse under its own gravitational weight by thermal pressure. The energy required to sustain this thermal pressure comes from nuclear reactions in the core of the star, essentially consisting of lighter elements fusing to form progressively heavier elements and releasing energy in the process. Ultimately, if the star is large enough (greater than 8-10 solar masses), iron is produced which has the lowest binding energy of any element. Further fusion with iron to produce heavier elements absorbs energy rather than releases it and the production of thermal energy stops. At this point, without additional thermal energy to resist the inward pull of gravity, pressure in the core builds. This increases the temperature in the core, which in turn cause photodisintegration of iron atoms in an endothermic reaction that escalates the whole process. Soon, the pressure and density reach a critical point where the atomic structure itself collapses in a process known as reverse beta decay where protons and electrons combine to form neutrons and electron neutrinos, and the star begins to collapse under its own weight.
Show more

160 Read more

Topics in Core-Collapse Supernova Theory: The Formation of Black Holes and the Transport of Neutrinos

Topics in Core-Collapse Supernova Theory: The Formation of Black Holes and the Transport of Neutrinos

time and eventually merge; this potentially leaves a hypermassive white dwarf that is initially ther- mally supported above the Chandrasekhar mass. The settling of the high-entropy merger remnants onto the inner core slowly raises the temperature, eventually triggering the runaway thermonuclear explosion. The single-degenerate model consists of a white dwarf accreting from a companion star, e.g., a subgiant or red giant. As more material is accreted, the central temperature increases and, like in the double-degenerate scenario, a runaway explosion is triggered. The other large uncertainty in Type-Ia supernova theory is the process by which the carbon is ignited (Hillebrandt and Niemeyer 2000). Simulations have shown that in a pure deflagration, i.e., a subsonic burning front, the outer layers of the white dwarf expand before ignited. This leads to too many intermediate mass elements compared to what is observed. However, a pure detonation, a supersonic burning front, has the opposite problem. It produces too little intermediate mass elements and instead forming too many iron-group nuclei. The delayed detonation model, where a deflagration transitions into a detonation can be made to reproduce observed abundances, but the physical mechanism of the transition is un- clear. Type-Ia supernovae are not the topic of this thesis; we refer the reader to reviews Hillebrandt and Niemeyer (2000), Wang and Han (2012) on Type-Ia supernovae for more detailed information. All of the remaining types and subtypes of supernovae stem from essentially the same process, the collapse of the iron core in an evolved massive star, it is the central engine of these supernovae that is of interest in this thesis. Before delving further into the inner workings of a core-collapse supernova in the following section, I will briefly describe the various electromagnetic observational signatures of core-collapse supernovae. The two other subcategories of Type-I supernovae classify the hydrogen-poor core-collapse events. These two subcategories encompass ∼ 19% of all supernovae. The remaining supernovae are of Type-II and comprise ∼ 54% of observed supernovae in the LOSS survey. Type-II are divided into four main categories, but as previously mentioned, all contain strong hydrogen lines in their spectra.
Show more

168 Read more

Core Collapse Supernova Physics in the Multi Messenger Era

Core Collapse Supernova Physics in the Multi Messenger Era

support and positive influence has helped push me through to the finish line 4 . Julie, your cross-stitch will forever have a place on my fridge for morn- ing (and any time) motivation. To Alex Urban, thank you for being you. Over the eight years since I first met you, you’ve always unconditionally offered your support and friendship. Thank you for holding me down in Pasadena, for Baton Rouge, for loving little sweets like your own, for everything. May we chronicle meow meow kitty adventures (starring Indica, in the role of a lifetime) forever and always. To Brittany Kamai, thank you for being a breath of fresh air in an often suffocatingly toxic work environment. Our check-ins on signal kept me on pace while writing up, and brought light to often other- wise dull days. I deeply appreciate you and your sparkle, and am constantly inspired by you. You are a wonderful and powerful human fighting for long- overdue change, and the field (not to mention my life) is so much better for you in it. To my fellow LIGO grad siblings in 364 W. Bridge, Craig Cahillane, Max Isi, Surabhi Sachdev, and Aaron Markowitz; thank you for the fun ad- ventures and office mate kinship. To my postdoc office mates Rory Smith and Michael Coughlin, thank you for your friendship. I’ve known you since the start of my (our?) LIGO days, and it has been a joy to watch you grow up academically and move to faculty (!!!) positions. You are two of the kindest hearted and talented researchers I know, and I can’t wait to see the amazing things you’ll continue to do. To Eric Gustafson and Syd Meshkov, talking with you about core-collapse supernovae after some of my LIGO seminars is a really happy and positive experience from Caltech that I’ll always cherish. Thank you for the advice, chats, and friendship. To Mary Massinger, Jamie Rollins, TJ Massinger, Eric Quintero, Zach Korth, Andrew Wade, and Aidan Brooks; thank you for the (reliably very interesting) chats at Wednesday beer hour and Friday coffee, which were always high points of my week. To Cody Messick, thank you for the truly magical three months in early 2016 when you visited Pasadena - you are awesome.
Show more

236 Read more

On the association between core-collapse supernovae and H II regions

On the association between core-collapse supernovae and H II regions

The past decade has seen major advances in establishing the pro- genitors of core-collapse supernovae (ccSNe; Smartt 2009). Three discrete subpopulations of hydrogen-rich ccSNe are known exhibit- ing plateau’s (II-P), slow declines (II-L) and rapid declines (IIb) in their light curves (Arcavi et al. 2012), representing progressively lower hydrogen envelope masses. It has been empirically estab- lished that the most common of these (II-P) are the direct progeny of red supergiants (Smartt et al. 2009). Some of the rarer subtypes (II-L and IIb) have been proposed to originate from yellow su- pergiants, hydrogen-rich Wolf–Rayet stars or interacting binaries, while hydrogen-rich ccSNe with narrow components in their spectra (IIn) seem to involve interactions with dense circumstellar material (Kiewe et al. 2012).
Show more

17 Read more

Simulations of stripped core-collapse supernovae in close binaries

Simulations of stripped core-collapse supernovae in close binaries

During the supernova, Richtmeyer-Meshkov (the impul- sive form of Rayleigh-Taylor) instabilities (RMI) are ex- pected to be present, which have been found to appear once reverse shocks form at the interfaces between dis- continuities in the density gradient (Kane et al. ). Such discontinuities are present in Type Ibc progenitors at the interface between the carbon-oxygen boundary in the core and, if any substantial fraction of hydrogen remains in the envelope, also at the helium-hydrogen boundary. However, these discontinuities tend to be smoothed during the con- version from the one-dimensional stellar model and sub- sequent relaxation of the SPH particles. Proper treatment of the RMI requires a prescription of artificial conductiv- ity that is not included in the current SPH codes in AMUSE. This instability is expected to be a significant factor in the mixing of stellar material early in the evolution of SNRs, and so any evaluation of the fate of the composition of the supernova ejecta must take this into account.
Show more

19 Read more

Experimental Approach to Explosive Hydrogen Burning in X-Ray Bursts and Core-Collapse Supernovae

Experimental Approach to Explosive Hydrogen Burning in X-Ray Bursts and Core-Collapse Supernovae

Since nuclear reactions runs through proton-rich nuclear region in the explosive hydrogen burning process, this process has a great chance to contribute for p-nucleus production in the[r]

6 Read more

Core-collapse supernova progenitor constraints using the spatial distributions of massive stars in local galaxies

Core-collapse supernova progenitor constraints using the spatial distributions of massive stars in local galaxies

Kangas et al.: Supernova progenitor constraints using the spatial distributions of massive stars in local galaxies Type Ic SNe, on the other hand, have an NCR distribution, and a mean NC[r]

19 Read more

Neutrino Radiation Transport and Other Topics in High Energy Density Astrophysics

Neutrino Radiation Transport and Other Topics in High Energy Density Astrophysics

Core-collapse supernovae (CCSNe) and gamma-ray bursts (GRBs) are among the most brilliant explosions in the universe, and the mechanisms driving both are deeply interrelated. As the name suggests, CCSNe result from the collapse of massive stars. The explosion expels matter that forms the vast majority of elements heavier than helium but lighter than iron and leaves behind an incredibly dense neutron star. Though supernovae have been seen throughout history and the modern theory of CCSNe began in the 1960s, simulations show that our understanding is still incomplete. Since we cannot see into the depths of exploding stars (except for exceedingly rare galactic events, where we would observe a neutrino and potentially a gravitational wave signal), we rely on simulations to understand what can and what can not cause a star to explode. But these simulations, too, suffer from an incomplete understanding of the properties of matter at high densities and the highly nonlinear processes and instabilities in neutrino radiation magentohydrodynamics. Explanations of exotic, extremely energetic supernovae (“hypernovae”) and their long-duration GRB counterparts are particularly elusive, as they also launch a hyper-relativistic and tightly collimated jet. In parts of this thesis, I use simulations of CCSNe to further our theoretical understanding of how each of these elements contributes to CCSNe and to predict what we might observe from future nearby CCSNe.
Show more

264 Read more

Expected impact from weak reactions with light nuclei in corecollapse supernova simulations

Expected impact from weak reactions with light nuclei in corecollapse supernova simulations

The simulations are launched from a 11.2 M progenitor [36]. It was evolved consistently though core collapse, bounce and post bounce phases using the EOS HS(DD2), taking fully into account light nuclear clusters. We compare results from two simulations, i.e. with and without including weak rates with light clusters based on the selection given in the right panel of Table 1. In general, the post bounce phase of core-collapse supernovae is determined from mass accretion from the still

7 Read more

Exam Reivew 2--Big Bang, Stars, Galaxies, Solar System, and Earth-Moon-Sun Systems.doc

Exam Reivew 2--Big Bang, Stars, Galaxies, Solar System, and Earth-Moon-Sun Systems.doc

Which object is formed from the core collapse of a star greater than 20 solar masses and has such strong surface gravity that light cannot even escape it?. 17.[r]

8 Read more

An r−process macronova/kilonova in GRB 060614: evidence for the merger of a neutron star-black hole binary

An r−process macronova/kilonova in GRB 060614: evidence for the merger of a neutron star-black hole binary

Figure 1. The excess component in the afterglow of GRB 060614 compared with some core-collapse SNe. The data of excess in GRB 060614 are adopted from [14]. The data of SN 1998bw, the prototype of SN associated with GRB, is taken from [8]; the data of SN 2010bh, the most rapid to reach the peak SN associated with GRB, is taken from [19]; and the data of SN 2008ha, the weakest core-collapse SN known so far, is taken from [18]. The dashed lines are macronova model lightcurves generated from numerical simulation for the ejecta from a BH − NS merger, with a velocity ∼ 0 . 2 c and mass M ej ∼ 0 . 1 M , by [4], with shadows represent a possible uncertainties of
Show more

6 Read more

Gamma Ray Bursts Generated by Hyper Accreting Kerr Black Hole

Gamma Ray Bursts Generated by Hyper Accreting Kerr Black Hole

The aim of this paper is to explore relativistic disk accreting Kerr black hole as the potential central source of gamma ray bursts. We begin with the detailed discussions of merger of compact binaries involving neutron stars and super massive star gravitational core collapse. Particularly, investigating super massive star gravitational core collapse leads to newly formed rapidly spinning, black holes and compact core mergers (perhaps NS-NS and NS-BH). Finally, we infer the radiative heating flux density due to viscous and magnetic energy dissipation in general relativistic Kerr Black Hole. In Section 2 we present a brief description of general relativistic resistive MHD formulations. The relativistic accretion flow in resistive MHD and the resulting radiation basically explained as the X-ray luminosity of the central source explored in Section 3. Finally, in Section 4 we provide a summary and draw the concluding remarks.
Show more

18 Read more

Causes, Effects and Remedies to the incessant Building Collapse in Lagos State, Nigeria

Causes, Effects and Remedies to the incessant Building Collapse in Lagos State, Nigeria

The quantification of the complete effects of any collapse is extremely difficult as there are so many factors involved, and these including emotional and subjective factors. Apart from the number of deaths that can often be truly identified, the rest of the effects are surrounded by so many uncertainties which make the analysis only approximate. Leaving aside the grossly quantifiable economic sums, the stress, trauma and shocks may have some far-reaching effects upon the building owner and/or employees, occupant, and others involved in one way or the other with the structure. The negative impact of such failures on the social-economic development of our economy is obvious. As many previous lives are lost, the nation loses the contribution that could have come from these victims towards the socio-economic growth of the nation. More so, this increasing rate of death from building collapse in Nigeria runs against the United Nations MDGs (Millennium Development Goals) programmes aimed at reducing the mortality rate and improving safety and life expectancy of the world population. For this, incidence of deaths during the collapse is deeply analysed in the remaining parts of this research work as to proffering solutions towards reducing it. 5.1 BUILDING FAILURE
Show more

16 Read more

Show all 10000 documents...