84
2 Observations of Radio and X-ray Pulsars
Table 2.4 Luminosities and flux intensities of the typical supernova remnants and their compact
objects
Supernovae
Compact
objects
Luminosity of
supernova
remnant
lg(L x ) (erg/s)
Flux intensity of
compact object
F x (erg/cm
2
/s)
Luminosity of
compact object
lg(L x ) (erg/s)
Crab
PSR B0531+21
37.38
2.1×10
-9
35.98
SNR0540-69.3 PSR B0540−69
37.02
2.9×10
-12
36.38
VelaXYZ
PSR B0833−45
33.77
4.0×10
-12
32.91
MSH15-52
PSR B1509−58
35.27
6.5×10
-14
34.37
CTB80
PSR B1951+32
34.68
2.0×10
-12
33.80
and those of the supernova remnants, as well as the directions of the detected pulsars,
the performances of the detectors and the integrated time of signals.
The statistical results of the luminosities and the flux intensities of typical supernova remnants and their compact objects are listed in Table 2.4, from which it is
shown that the X-ray flux intensities radiated from the pulsars are far less than those
from synchrotron radiations of the nebulae around them. The total of the radiations
from the X-ray pulsars are very small in the supernova remnants, and the radiation
ratios for the first four pulsars in Table 2.4 are 4%, 25%, 10% and 4%, respectively.
For example, there are about 780 X-ray photons each second received by using
a detector with an effective collecting area of 0.5 m
2 for the Crab pulsar, and about
7800 photons from the Crab Nebula. Obviously, the background noise is 10 times
more than the X-ray signals from the pulsar. Generally, it is impossible that the
pulsating profiles of X-ray pulsars are directly obtained by using total of the photons
from one pulsating period. Nevertheless, the background noises have no periodicity,
and produce additional counts of the photons randomly and uniformly; the pulsating
signals have periodicity, and their pulses will be accumulated to intensify. Therefore,
the clearly distinguishable pulse profiles of X-ray pulsars can usually be obtained by
period folding and synchronization averaging.
References
1. Backer DC, Kulkarni SR et al (1982) A millisecond pulsar. Nature 300(5893):315–318
2. Nicastro L, Cusumano G et al (2004) BeppoSAX observation of PSR B1937+21. Astron
Astrophys 413(3):1065–1072
3. Arzoumanian Z, Van der Hooft F, van den Heuvel EPJ (1999) Pulsar timing, general relativity and
the internal structure of neutron stars. Koninklijke Nederlandse Akademie van Wetenschappen,
Amsterdam
2 Observations of Radio and X-ray Pulsars
Table 2.4 Luminosities and flux intensities of the typical supernova remnants and their compact
objects
Supernovae
Compact
objects
Luminosity of
supernova
remnant
lg(L x ) (erg/s)
Flux intensity of
compact object
F x (erg/cm
2
/s)
Luminosity of
compact object
lg(L x ) (erg/s)
Crab
PSR B0531+21
37.38
2.1×10
-9
35.98
SNR0540-69.3 PSR B0540−69
37.02
2.9×10
-12
36.38
VelaXYZ
PSR B0833−45
33.77
4.0×10
-12
32.91
MSH15-52
PSR B1509−58
35.27
6.5×10
-14
34.37
CTB80
PSR B1951+32
34.68
2.0×10
-12
33.80
and those of the supernova remnants, as well as the directions of the detected pulsars,
the performances of the detectors and the integrated time of signals.
The statistical results of the luminosities and the flux intensities of typical supernova remnants and their compact objects are listed in Table 2.4, from which it is
shown that the X-ray flux intensities radiated from the pulsars are far less than those
from synchrotron radiations of the nebulae around them. The total of the radiations
from the X-ray pulsars are very small in the supernova remnants, and the radiation
ratios for the first four pulsars in Table 2.4 are 4%, 25%, 10% and 4%, respectively.
For example, there are about 780 X-ray photons each second received by using
a detector with an effective collecting area of 0.5 m
2 for the Crab pulsar, and about
7800 photons from the Crab Nebula. Obviously, the background noise is 10 times
more than the X-ray signals from the pulsar. Generally, it is impossible that the
pulsating profiles of X-ray pulsars are directly obtained by using total of the photons
from one pulsating period. Nevertheless, the background noises have no periodicity,
and produce additional counts of the photons randomly and uniformly; the pulsating
signals have periodicity, and their pulses will be accumulated to intensify. Therefore,
the clearly distinguishable pulse profiles of X-ray pulsars can usually be obtained by
period folding and synchronization averaging.
References
1. Backer DC, Kulkarni SR et al (1982) A millisecond pulsar. Nature 300(5893):315–318
2. Nicastro L, Cusumano G et al (2004) BeppoSAX observation of PSR B1937+21. Astron
Astrophys 413(3):1065–1072
3. Arzoumanian Z, Van der Hooft F, van den Heuvel EPJ (1999) Pulsar timing, general relativity and
the internal structure of neutron stars. Koninklijke Nederlandse Akademie van Wetenschappen,
Amsterdam