95,297 research outputs found
Gamma-Ray Pulsar Studies with GLAST
Some pulsars have their maximum observable energy output in the gamma-ray
band, offering the possibility of using these high-energy photons as probes of
the particle acceleration and interaction processes in pulsar magnetospheres.
After an extended hiatus between satellite missions, the recently-launched
AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST)
Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models
developed based on past discoveries. With its greatly improved sensitivity,
better angular resolution, and larger energy reach than older instruments,
GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure
luminosities, light curves, and phase-resolved spectra with unprecedented
resolution. It will also have the potential to find radio-quiet pulsars like
Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar
astronomers is an important aspect of the LAT team's planning for pulsar
studies.Comment: 8 pages, 5 figures. To appear in the proceedings of "40 Years of
Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007,
McGill University, Montreal, Canad
Interpretation of the pulsed gamma ray emission from Vela
A model is proposed for the Vela pulsar in which the radio emission originates near the surface of the neutron star while the pulsed gamma ray emission is produced by synchrotron radiation near the speed of light cylinder. This model can explain the energy flux, double pulse structure, and phase shift with respect to the radio of the gamma ray emission and offers approximate quantitative predictions for other X-ray and gamma-ray fluxes
Magnetism and superconductivity in strongly correlated CeRhIn5
Specific heat studies of CeRhIn5 as functions of pressure and magnetic field
have been used to explore the relationship between magnetism and unconventional
superconductivity, both of which involve the 4f electron of Ce. Results of
these studies cannot be understood as a simple competition for Fermi-surface
states and require a new conceptual framework.Comment: 9 pages, 7 figure
SCUBA polarisation observations of the magnetic fields in the prestellar cores L1498 and L1517B
We have mapped linearly polarized dust emission from the prestellar cores
L1498 and L1517B with the James Clerk Maxwell Telescope (JCMT) using the
Submillimetre Common User Bolometer Array (SCUBA) and its polarimeter SCUBAPOL
at a wavelength of 850um. We use these measurements to determine the
plane-of-sky magnetic field orientation in the cores. In L1498 we see a
magnetic field across the peak of the core that lies at an offset of 19 degrees
to the short axis of the core. This is similar to the offsets seen in previous
observations of prestellar cores. To the southeast of the peak, in the
filamentary tail of the core, we see that the magnetic field has rotated to lie
almost parallel to the long axis of the filament. We hypothesise that the field
in the core may have decoupled from the field in the filament that connects the
core to the rest of the cloud. We use the Chandrasekhar-Fermi (CF) method to
measure the plane-of-sky field strength in the core of L1498 to be 10 +/- 7 uG.
In L1517B we see a more gradual turn in the field direction from the northern
part of the core to the south. This appears to follow a twist in the filament
in which the core is buried, with the field staying at a roughly constant 25
degree offset to the short axis of the filament, also consistent with previous
observations of prestellar cores. We again use the CF method and calculate the
magnetic field strength in L1517B also to be 30 +/- 10 uG. Both cores appear to
be roughly virialised. Comparison with our previous work on somewhat denser
cores shows that, for the denser cores, thermal and non-thermal (including
magnetic) support are approximately equal, while for the lower density cores
studied here, thermal support dominates.Comment: 6 pages, 2 figures; accepted for publication by MNRA
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