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Asymmetric Supernovae, Pulsars, Magnetars, and Gamma-Ray Bursts  [PDF]
J. Craig Wheeler,Insu Yi,Peter Hoeflich,Lifan Wang
Physics , 1999, DOI: 10.1086/309055
Abstract: We outline the possible physical processes, associated timescales, and energetics that could lead to the production of pulsars, jets, asymmetric supernovae, and weak gamma-ray bursts in routine circumstances and to a magnetar and perhaps stronger gamma-ray burst in more extreme circumstances in the collapse of the bare core of a massive star. The production of a LeBlanc-Wilson MHD jet could provide an asymmetric supernova and result in a weak gamma-ray burst when the jet accelerates down the stellar density gradient of a hydrogen-poor photosphere. The matter-dominated jet would be formed promptly, but requires 5 to 10 s to reach the surface of the progenitor of a Type Ib/c supernova. During this time, the newly-born neutron star could contract, spin up, and wind up field lines or turn on an alpha-Omega dynamo. In addition, the light cylinder will contract from a radius large compared to the Alfven radius to a size comparable to that of the neutron star. This will disrupt the structure of any organized dipole field and promote the generation of ultrarelativistic MHD waves (UMHDW) at high density and Large Amplitude Electromagnetic Waves (LAEMW) at low density. The generation of the these waves would be delayed by the cooling time of the neutron star about 5 to 10 seconds, but the propagation time is short so the UMHDW could arrive at the surface at about the same time as the matter jet. In the density gradient of the star and the matter jet, the intense flux of UMHDW and LAEMW could drive shocks, generate pions by proton-proton collision, or create electron/positron pairs depending on the circumstances. The UMHDW and LAEMW could influence the dynamics of the explosion and might also tend to flow out the rotation axis to produce a collimated gamma-ray burst.
Plasma Pressure Driven Asymmetric Supernovae and Highly Collimated Gamma-Ray Bursts  [PDF]
K. H. Tsui,C. E. Navia
Physics , 2012,
Abstract: During the process of collapse of a massive star, a cavity is generated between the central iron core and an outer stellar envelope. The dynamics of this cavity, filled with plasma and magnetic field of the rapidly rotating proto-magnetar's magnetosphere, is believed to be very relevant in understanding supernovae and gamma-ray bursts. The interactions of the pressurized conducting plasma and the magnetic fields are described by a set of magnetohydrodynamic (MHD) equations with poloidal and toroidal plasma flows not aligned with magnetic fields. A sequence of MHD equilibria in response to the increasing plasma pressure in the cavity, by continuous filling from the rotating magnetosphere, is solved to account for asymmetric supernovae, highly collimated gamma-ray burst jets, and also active galactic nucleus plasma torus. It is shown that the magnetosphere of the central compact star is likely the central engine of supernova and gamma-ray burst by feeding them plasma, magnetic energy, and rotational energy.
Gamma-ray lines from SN2014J  [PDF]
Thomas Siegert,Roland Diehl
Physics , 2015,
Abstract: On 21 January 2014, SN2014J was discovered in M82 and found to be the closest type Ia supernova (SN Ia) in the last four decades. INTEGRAL observed SN2014J from the end of January until late June for a total exposure time of about 7 Ms. SNe Ia light curves are understood to be powered by the radioactive decay of iron peak elements of which $^{56}$Ni is dominantly synthesized during the thermonuclear disruption of a CO white dwarf (WD). The measurement of $\gamma$-ray lines from the decay chain $^{56}$Ni$\rightarrow$$^{56}$Co$\rightarrow$$^{56}$Fe provides unique information about the explosion in supernovae. Canonical models assume $^{56}$Ni buried deeply in the supernova cloud, absorbing most of the early $\gamma$-rays, and only the consecutive decay of $^{56}$Co should become directly observable through the overlaying material several weeks after the explosion when the supernova envelope dilutes as it expands. Surprisingly, with the spectrometer on INTEGRAL, SPI, we detected $^{56}$Ni $\gamma$-ray lines at 158 and 812 keV at early times with flux levels corresponding to roughly 10% of the total expected amount of $^{56}$Ni, and at relatively small velocities. This implies some mechanism to create a major amout of $^{56}$Ni at the outskirts, and at the same time to break the spherical symmetry of the supernova. One plausible explanation would be a belt accreted from a He companion star, exploding, and triggering the explosion of the white dwarf. The full set of observations of SN2014J show $^{56}$Co $\gamma$-ray lines at 847 and 1238 keV, and we determine for the first time a SN Ia $\gamma$-ray light curve. The irregular appearance of these $\gamma$-ray lines allows deeper insights about the explosion morphology from its temporal evolution and provides additional evidence for an asymmetric explosion, from our high-resolution spectroscopy and comparisons with recent models.
Gamma-ray bursts, BL Lacs, Supernovae, and Interacting Galaxies  [PDF]
Anup Rej
Physics , 1998,
Abstract: Within the framework of star formation in starburst galaxies undergoing interactions, connections among the red quasars, the BL Lacs, and the Blazars with the gamma-ray bursts are discussed in the light of the "hypernovae" scenario. It is proposed that the gamma-ray bursts occur primarily in the star formation regions in starburst environments, and arise from the core-collapse of super-massive Wolf-Rayet stars, that are formed in interacting systems. In this interacting environment star formations cause supernovae explosions. As the stars explode, shock waves propagate outward and collide with the ambient medium, forming a high-density super-shell, where intense star formation begins; subsequently supernovae explosions within the shell cause an outward expansion of the shell. In another scenario of star formation the interactions among the large gas-rich low-surface brightness (LSB) spiral galaxies give rise to fragmentation of their tidal tails. These fragmented clouds collapse to compact dwarfs, which undergo rapid star formation. In such a scenario of interactions, where most quasars are observed, we discuss the MgII absorption lines in GRB 970508, whose spectra resemble a BL Lac object, and the spectral evolution of GRB 971214 that may also indicate a similar connection. Beside the BL Lac connection, the recent discovery of GRB 980425 in a nearby galaxy indicates asymmetric supernovae explosions that give rise to relativistic jets. We propose that the gamma-ray light curves arise due to inverse Compton scattering of soft-photons from precessing relativistic blobs of plasma moving in jets. This brings into light the mechanisms of supernova explosions, that give birth to relativistic jets.
Conference Summary: Supernovae and Gamma-Ray Bursts  [PDF]
J. Craig Wheeler
Physics , 1999,
Abstract: There are hints that nearby Type Ia supernovae may be a little different than those at large redshift. Confidence in the conclusion that there is a cosmological constant and an accelerating Universe thus still requires the hard work of sorting out potential systematic effects. Polarization data show that core-collapse supernovae (Type II and Ib/c) probably depart strongly from spherical symmetry. Evidence for exceedingly energetic supernovae must be considered self-consistently with evidence that they are asymmetric, a condition that affects energy estimates. Jets arising near the compact object can produce such asymmetries. There is growing conviction that gamma-ray bursts intrinsically involve collimated or jet-like flow and hence that they are also strongly asymmetric. SN 1998bw is a potential rosetta stone that will help to sort out the physics of explosive events. Are events like SN 1998bw more closely related to "ordinary" supernovae or "hypernovae?" Do they leave behind neutron stars as "ordinary" pulsars or "magnetars" or is the remnant a black hole? Are any of these events associated with classic cosmic gamma-ray bursts as suggested by the supernova-like modulation of the afterglows of GRB 970228, GRB 980326 and GRB 990712?
Astrophysical Gamma Ray Emission Lines  [PDF]
R. Ramaty,R. E. Lingenfelter
Physics , 1995,
Abstract: We review the wide range of astrophysical observations of gamma ray emission lines and we discuss their implications. We consider line emission from solar flares, the Orion molecular cloud complex, supernovae 1987A and 1991T, the supernova remnants Cas A and Vela, the interstellar medium, the Galactic center region and several Galactic black hole candidates. The observations have important, and often unique, implications on particle acceleration, star formation, processes of nucleosynthesis, Galactic evolution and compact object physics.
The Broad-Lined Type Ic SN 2012ap and the Nature of Relativistic Supernovae Lacking a Gamma-ray Burst Detection  [PDF]
D. Milisavljevic,R. Margutti,J. T. Parrent,A. M. Soderberg,R. A. Fesen,P. Mazzali,K. Maeda,N. E. Sanders,S. B. Cenko,J. M. Silverman,A. V. Filippenko,A. Kamble,S. Chakraborti,M. R. Drout,R. P. Kirshner,T. E. Pickering,K. Kawabata,T. Hattori,E. Y. Hsiao,M. D. Stritzinger,G. H. Marion,J. Vinko,J. C. Wheeler
Physics , 2014, DOI: 10.1088/0004-637X/799/1/51
Abstract: We present ultraviolet, optical, and near-infrared observations of SN 2012ap, a broad-lined Type Ic supernova in the galaxy NGC 1729 that produced a relativistic and rapidly decelerating outflow without a gamma-ray burst signature. Photometry and spectroscopy follow the flux evolution from -13 to +272 days past the B-band maximum of -17.4 +/- 0.5 mag. The spectra are dominated by Fe II, O I, and Ca II absorption lines at ejecta velocities of 20,000 km/s that change slowly over time. Other spectral absorption lines are consistent with contributions from photospheric He I, and hydrogen may also be present at higher velocities (> 27,000 km/s). We use these observations to estimate explosion properties and derive a total ejecta mass of 2.7 Msolar, a kinetic energy of 1.0x10^{52} erg, and a 56Ni mass of 0.1-0.2 Msolar. Nebular spectra (t > 200d) exhibit an asymmetric double-peaked [OI] 6300,6364 emission profile that we associate with absorption in the supernova interior, although toroidal ejecta geometry is an alternative explanation. SN 2012ap joins SN 2009bb as another exceptional supernova that shows evidence for a central engine (e.g., black-hole accretion or magnetar) capable of launching a non-negligible portion of ejecta to relativistic velocities without a coincident gamma-ray burst detection. Defining attributes of their progenitor systems may be related to notable properties including above-average environmental metallicities of Z > Zsolar, moderate to high levels of host-galaxy extinction (E(B-V) > 0.4 mag), detection of high-velocity helium at early epochs, and a high relative flux ratio of [Ca II]/[O I] > 1 at nebular epochs. These events support the notion that jet activity at various energy scales may be present in a wide range of supernovae.
Supernovae and Gamma Ray Bursts  [cached]
M. Della Valle
Revista mexicana de astronomía y astrofísica , 2007,
Abstract: Se revisa el estatus observacional de la conexi on Supernova (SN)/Estallido de Rayos-Gamma (GRB). Recientes (y no tan recientes) observaciones de GRBs largos sugieren que una fracci on signi cativa de ellos (pero no todos) est an asociados con supernovas brillantes del tipo Ib/c. Estimaciones actuales de las tasas de producci on de GRBs y SNs dan una raz on para GRB/SNe-Ibc en el rango 0:4%
The Nature of Gamma Ray Burst Supernovae  [PDF]
Zach Cano
Physics , 2012,
Abstract: Gamma Ray Bursts (GRBs) and Supernovae (SNe) are among the brightest and most energetic physical processes in the universe. It is known that core-collapse SNe arise from the gravitational collapse and subsequent explosion of massive stars (the progen- itors of nearby core-collapse SNe have been imaged and unambiguously identified). It is also believed that the progenitors of long-duration GRBs (L-GRBs) are massive stars, mainly due to the occurrence and detection of very energetic core-collapse su- pernovae that happen both temporally and spatially coincident with most L-GRBs. However many outstanding questions regarding the nature of these events exist: How massive are the progenitors? What evolutionary stage are they at when they explode? Do they exist as single stars or in binary systems (or both, and to what fractions)? The work presented in this thesis attempts to further our understanding at the types of progenitors that give rise to long-duration GRB supernovae (GRB-SNe). This work is based on optical photometry obtained for three GRB-SNe events: GRB 060729, GRB 090618 and XRF 100316D (an X-Ray Flash is similar to a L-GRB, but has a lower peak energy). For GRB 060729 and GRB 090618 we model the optical light curves and account for light coming from three sources: the host galaxy, the afterglow and the supernova. When we remove the host flux, and model the afterglow, the re- maining flux resembles that of a SN, both in the shape of the light curve and the shape of the spectral energy distribution. Our investigation of XRF 100316D and its spectroscopically-confirmed Ic-BL SN 2010bh is more detailed as we were able to obtain optical and infrared data in many filters, which we utilize to created a quasi-bolometric light curve that we model to determine physical parameters of the SN...
Collapsars, Gamma-Ray Bursts, and Supernovae  [PDF]
S. E. Woosley,A. I. MacFadyen,A. Heger
Physics , 1999,
Abstract: A diverse range of phenomena is possible when a black hole experiences very rapid accretion from a disk due to the incomplete explosion of a massive presupernova star endowed with rotation. In the most extreme case, the outgoing shock fails promptly in a rotating helium star, a black hole and an accretion disk form, and a strong gamma-ray burst (GRB) results. However, there may also be more frequently realized cases where the black hole forms after a delay of from several tens of seconds to several hours as approximately 0.1 to 5 solar masses falls back into the collapsed remnant following a mildly successful supernova explosion. There, the same MHD mechanisms frequently invoked to produce GRBs would also produce jets in stars already in the process of exploding. The presupernova star could be a Wolf-Rayet star or a red or blue supergiant. Depending upon its initial pressure, the collimation of the jet may also vary since ``hot'' jets will tend to diverge and share their energy with the rest of the star. From these situations, one expects diverse outcomes ranging from GRBs with a large range of energies and durations, to asymmetric, energetic supernovae with weak GRBs. SN 1998bw may have been the explosion of a star in which fall back produced a black hole and a less collimated jet than in the case of prompt black hole formation.
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