6,249 research outputs found
Radio Quiet Pulsars with Ultra-Strong Magnetic Fields
The notable absence of radio pulsars having measured magnetic dipole surface
field strengths above Gauss naturally raises the
question of whether this forms an upper limit to pulsar magnetization. Recently
there has been increasing evidence that neutron stars possessing higher dipole
spin-down fields do in fact exist, including a growing list of anomalous X-ray
pulsars (AXPs) with long periods and spinning down with high period
derivatives, implying surface fields of -- Gauss.
Furthermore, the recently reported X-ray period and period derivative for the
Soft Gamma-ray Repeater (SGR) source SGR1806-20 suggest a surface field around
Gauss. None of these high-field pulsars have yet been detected as
radio pulsars. We propose that high-field pulsars should be radio-quiet because
electron-positron pair production in their magnetospheres, thought to be
essential for radio emission, is efficiently suppressed in ultra-strong fields
( Gauss) by the action of photon splitting, a
quantum electrodynamical process in which a photon splits into two. Our
computed radio quiescence boundary in the radio pulsar diagram,
where photon splitting overtakes pair creation, is located just above the
boundary of the known radio pulsar population, neatly dividing them from the
AXPs. We thus identify a physical mechanism that defines a new class of
high-field radio-quiet neutron stars that should be detectable by their pulsed
emission at X-ray and perhaps -ray energies.Comment: 4 pages, including one figure and one table, in AASTeX emulatapj
format, Astrophysical Journal Letters, in pres
High magnetic field pulsars and magnetars: a unified picture
We propose a unified picture of high magnetic field radio pulsars and
magnetars by arguing that they are all rotating high-field neutron stars, but
have different orientations of their magnetic axes with respective to their
rotation axes. In strong magnetic fields where photon splitting suppresses pair
creation near the surface, the high-field pulsars can have active inner
accelerators while the anomalous X-ray pulsars cannot. This can account for the
very different observed emission characteristics of the anomalous X-ray pulsar
1E 2259+586 and the high field radio pulsar PSR J1814-1744. A predicted
consequence of this picture is that radio pulsars having surface magnetic field
greater than about G should not exist.Comment: 5 pages, emulateapj style, accepted for publication in the ApJ
Letter
McLean Sea-land Service and related services
Thesis (M.B.A.)--Boston Universit
High Energy Neutrinos and Photons from Curvature Pions in Magnetars
We discuss the relevance of the curvature radiation of pions in strongly
magnetized pulsars or magnetars, and their implications for the production of
TeV energy neutrinos detectable by cubic kilometer scale detectors, as well as
high energy photons.Comment: 19 pages, 4 figures, to appear in JCA
- …