43 research outputs found
A White Dwarf Merger Paradigm for Supernovae and Gamma-Ray Bursts
Gamma-ray bursts can appear to be a hundred times as luminous as supernovae,
but their underlying energy source(s) have remained a mystery. However, there
has been evidence for some time now of an association of gamma-ray bursts with
supernovae of Type Ib and Ic, a fact which has been exploited by a number of
models, to explain the gamma-ray burst phenomenon. Here we interpret the
results of basic observations of SN 1987A and of pulsars in globular clusters,
to propose the energy source, which powers at least some long-duration
gamma-ray bursts, as core-collapse following the merger of two white dwarfs,
either as stars or stellar cores. The beaming and intrinsic differences among
gamma-ray bursts arise, at least in part, from differing amounts and
composition of the gas in the merged stellar common envelopes, with the more
energetic bursts resulting from mergers within less massive envelopes. In order
for the beams/jets associated with gamma-ray bursts to form in mergers within
massive common envelopes (as with SN 1987A), much of the intervening stellar
material in the polar directions must be cleared out by the time of
core-collapse, or the beams/jets themselves must clear their own path. The
core-collapse produces supernovae of Type Ib, Ic, or II (as with SN 1987A, a
SNa IIp), leaving a weakly magnetized neutron star remnant with a spin period
near 2 milliseconds. There is no compelling reason to invoke any other model to
account for gamma-ray bursts. Far from being an unusual event, SN 1987A is
typical, having the same merger source of initiation as 95% of all supernovae,
the rare exceptions being Ia's induced via gradual accretion from a binary
companion, and Fe catastrophe II's.Comment: 11 pages, 0 figures. Accepted for publication in ApJ Letter
Pulsar-driven Jets in Supernovae, Gamma-Ray Bursts, and the Universe
The bipolarity of Supernova 1987A can be understood through its very early
light curve observed from the CTIO 0.4-m telescope and IUE FES, and following
speckle observations of the `Mystery Spot' by two groups. These indicate a
highly directional beam/jet of light/particles, with initial collimation
factors in excess of 10,000 and velocities in excess of 0.95 c, as an impulsive
event of up to 1e-5 solar masses interacting with circumstellar material. These
can be produced by a model proposed in 1972, by Bolotovskii and Ginzburg, which
employs pulsar emission from polarization currents induced/(modulated faster
than c) beyond the pulsar light cylinder by the periodic electromagnetic field
(supraluminally induced polarization currents -- SLIP). SLIP accounts for the
disruption of progenitors in supernova explosions and their anomalous dimming
at cosmological distances, jets from Sco X-1 and SS 433, the lack/presence of
intermittent pulsations from the high/low luminosity low mass X-ray binaries,
long/short gamma-ray bursts and predicts that their afterglows are the pulsed
optical/near infrared emission associated with these pulsars. SLIP may also
account for the TeV e+/e- results from PAMELA and ATIC, the WMAP `Haze'/Fermi
`Bubbles', and the r-process. SLIP jets from SNe of the first stars may allow
galaxies to form without dark matter, and explain the peculiar,
non-gravitational motions observed from pairs of distant galaxies by GALEX.Comment: This article has been published in the open source journal, Advances
in Astronomy: http://www.hindawi.com/journals/aa/2012/898907 This arXiv
version is out of date. arXiv admin note: substantial text overlap with
arXiv:0909.2604 (Note: but less so by v2, Also Brook Sandford in Ackn. -JM
A new mechanism for generating broadband pulsar-like polarization
Observational data imply the presence of superluminal electric currents in
pulsar magnetospheres. Such sources are not inconsistent with special
relativity; they have already been created in the laboratory. Here we describe
the distinctive features of the radiation beam that is generated by a rotating
superluminal source and show that (i) it consists of subbeams that are narrower
the farther the observer is from the source: subbeams whose intensities decay
as 1/R instead of 1/R^2 with distance (R), (ii) the fields of its subbeams are
characterized by three concurrent polarization modes: two modes that are
'orthogonal' and a third mode whose position angle swings across the subbeam
bridging those of the other two, (iii) its overall beam consists of an
incoherent superposition of such coherent subbeams and has an intensity profile
that reflects the azimuthal distribution of the contributing part of the source
(the part of the source that approaches the observer with the speed of light
and zero acceleration), (iv) its spectrum (the superluminal counterpart of
synchrotron spectrum) is broader than that of any other known emission and
entails oscillations whose spacings and amplitudes respectively increase and
decrease algebraically with increasing frequency, and (v) the degree of its
mean polarization and the fraction of its linear polarization both increase
with frequency beyond the frequency for which the observer falls within the
Fresnel zone. We also compare these features with those of the radiation
received from the Crab pulsar.Comment: 8 pages, 8 figure