4 research outputs found
Possible evolution of dim radio quiet neutron star 1E 1207.4-5209 based on a B-decay model
Dim radio-quiet neutron star (DRQNS) 1E 1207.4-5209 is one of the most
heavily examined isolated neutron stars. Wide absorption lines were observed in
its spectrum obtained by both XMM-Newton and Chandra X-ray satellites. These
absorption lines can be interpreted as a principal frequency centered at 0.7
keV and its harmonics at 1.4, 2.1 and possibly 2.8 keV. The principal line can
be formed by resonant proton cyclotron scattering leading to a magnetic field
which is two orders of magnitude larger than the perpendicular component of the
surface dipole magnetic field (B) found from the rotation period (P) and the
time rate of change in the rotation period (\.{P}) of 1E 1207.4-5209. Besides,
age of the supernova remnant (SNR) G296.5+10.0 which is physically connected to
1E 1207.4-5209 is two orders of magnitude smaller than the characteristic age
(=P/2\.{P}) of the neutron star. These huge differences between the
magnetic field values and the ages can be explained based on a B-decay model.
If the decay is assumed to be exponential, the characteristic decay time turns
out to be several thousand years which is three orders of magnitude smaller
than the characteristic decay time of radio pulsars represented in an earlier
work. The lack of detection of radio emission from DRQNSs and the lack of point
sources and pulsar wind nebulae in most of the observed SNRs can also be partly
explained by such a very rapid exponential decay. The large difference between
the characteristic decay times of DRQNSs and radio pulsars must be related to
the differences in the magnetic fields, equation of states and masses of these
isolated neutron stars.Comment: 13 pages, 1 figur
Influences of neutron star parameters on evolutions of different types of pulsar; evolutions of anomalous X-ray pulsars, soft gamma repeaters and dim isolated thermal neutron stars on the P-\.{P} diagram
Influences of the mass, moment of inertia, rotation, absence of stability in
the atmosphere and some other parameters of neutron stars on the evolution of
pulsars are examined. It is shown that the locations and evolutions of soft
gamma repeaters, anomalous X-ray pulsars and other types of pulsar on the
period versus period derivative diagram can be explained adopting values of
B G for these objects. This approach gives the possibility to explain
many properties of different types of pulsar.Comment: 18 pages, 1 figur
Early phases of different types of isolated neutron star
Two Galactic isolated strong X-ray pulsars seem to be in the densest
environments compared to other types of Galactic pulsar. X-ray pulsar
J1846-0258 can be in an early phase of anomalous X-ray pulsars and soft gamma
repeaters if its average braking index is ~1.8-2.0. X-ray pulsar J1811-1925
must have a very large average braking index (n~11) if this pulsar was formed
by SN 386AD. This X-ray pulsar can be in an early phase of evolution of the
radio pulsars located in the region P~50-150 ms and \.{P}~10
s/s of the P-\.{P} diagram. X-ray/radio pulsar J0540-69 seems to be evolving in
the direction to the dim isolated thermal neutron star region on the P-\.{P}
diagram. Possible progenitors of different types of neutron star are also
discussed.Comment: to appear in the International Journal of Modern Physics
Effects of the background radiation on radio pulsar and supernova remnant searches and the birth rates of these objects
In different directions of the Galaxy the Galactic background radio radiation
and radiation of complex star formation regions which include large number of
OB associations have different influences on radio pulsar (PSR) and supernova
remnant (SNR) searches. In this work we analyse the effects of these background
radiations on the observations of PSRs at 1400 MHz and SNRs at 1000 MHz. In the
interval l=0 the PSRs with flux F0.2 mJy and the SNRs
with surface brightness WmHzsr are
observable for all values of l and b. All the SNRs with
WmHzsr can be observed in the
interval 60l. We have examined samples of PSRs and SNRs to
estimate the birth rates of these objects in the region up to 3.2 kpc from the
Sun and also in the Galaxy. The birth rate of PSRs is about one in 200 years
and the birth rate of SNRs is about one in 65 years in our galaxy.Comment: revised versio