36x48 Vertical Poster

1
Pulsars Timing with the Nanshan Radio
Telescope J. P. Yuan, N. Wang, Z. Y.
Liu Xinjiang Astronomical Observatory,
CAS na.wang_at_xao.ac.cn

• A timing solution is determined by fitting only
  for the pulsar spin frequency and frequency
  derivative except for the Crab pulsar where the
  cubic polynomial is also fitted. The rotational
  parameters of four radio-loud gamma-ray pulsars
  are given in Table 2. A new glitch was detected
  in the Crab pulsar (the fractional jump in
  frequency ??g/ ?? gt 34(2)109) in 2011 November
  with a longer preceding interval of about 1300
  days. Figure 1 presents the results of timing
  analysis of PSR J06311036, showing a very large
  glitch with a frequency jump ??g 11106 Hz
  occurred in 2011. The dash in Figure 1 indicates
  the glitch epoch given by the Jodrell Bank glitch
  catalogue (Espinoza et al. 2011). Most of the
  jump ??g persist beyond the end of the data span.
  A phase-coherent fit is consistent with a glitch
  of ??g/?? 3.278106 and a decay model with a
  time constant td 160 d. The expanded plot in
  Figure 1(b) shows that there was an initial
  exponential decay with a small degree of recover
  Q 0.005. A large glitch was detected in PSR
  J09220638 with an unusual post-glitch behavior
  (see Figure 2).

• A comprehensive pulsar monitor program was
  carried out by the worldwide radio pulsar timing
  community in support the Fermi Gamma ray pulsar
  commission (Smith et al. 2008). More than 760
  pulsar ephemerides from radio observatories are
  obtained (Abdo et al. 2010). There are 218
  pulsars with high spin-down power (larger than
  1034 erg/s), many of them suffer from a high
  degree of timing noise. The pulsar timing is a
  significant tool to investigate the instability
  of pulsar spin-down, to investigate the electron
  distribution of interstellar media, to study the
  proper motion and velocity of pulsar, the detect
  gravitational waves, to test general relativity
  theory. Xinjiang Astronomical Observatory (XAO)
  operates a 25 meter dish at Nanshan to monitor
  about 300 pulsars.

Introduction
Table 2. Timing solutions for four pulsars.
Name EPOCH (Hz) (1012 s2) Data Range (MJD)
J05342200 55750 29.7106643314(4) 370.8536(1) 55666 55864
55980 29.7032966716(7) 370.7129(5) 55912 56018
J06311036 55450 3.4745585802(3) 1.26217(4) 55284 55698
55800 3.4745317754(4) 1.26461(7) 55707 55018
J0742-2822 55600 5. 9962323267(1) 0.605.25(1) 55238 55979
J20432740 55800 10. 4024488785(9) 0.133.35(5) 55271 55968
Discussions
Data analysis and Results

• For the Crab pulsar with the observed values of
  frequency and its first and second derivatives,
  the longer interval between the two latest
  glitches allow us to measure the braking index of
  the Crab pulsar using the equation .
  The braking index is calculated based on the
  timing parameters, giving a values of 2.571(3).
  The previous measured value of braking index show
  a remarkable constant value 2.51 (Lyne et al.
  1993). It is clear that there is an evident
  change in braking index. The reason of a varying
  braking index may be due to a varying particle
  wind strength (Wang et al. 2012).

• Pulsar timing observations at Nanshan commenced
  in 2000, with three sessions per month and an
  observing frequency at 1.54 GHz. Two different
  back-end systems were used since 2010, namely
  Analogue Filter-Bank and Digital Filter-Bank
  (DFB). DFB digitizes band-limited signal in the
  four Stokes parameters from each of the two
  orthogonal polarizations.
• The PSRCHIVE and TEMPO2 packages were used to
  analyze the data (Hotan, van Stran Manchester
  2004, Hobbs, Edwards Manchester 2006). Local
  arrival times were determined by correlating the
  observed average pulse profiles with standard
  pulse profiles. The basic timing model for the
  barycentric pulse phase, , as a function of
  time is
• where is the phase at time , and
  represent the pulse frequency, frequency
  derivative and frequency second derivative.
  Frequent observations at Nanshan revealed 49
  glitches up to December 2011. These include nine
  glitches that have not been reported in our
  earlier works (see Table 2 for details).

Figure 2. The glitch of PSR J09220638 . (a)
Variations of rotational frequency relative to
the pre-glitch solution. (b) An expanded plot of
frequency derivative. (c) Variations of
rotational frequency derivative.
Bibliography
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W., Manchester R. N., 2004, PASA, 21, 302 Lyne
A. G., Pritchard R. S., Graham Smith F., 1993,
MNRAS, 265, 1003 Smith D. A., Guillemot L.,
Camilo F. et al., 2008, AA, 492, 923 Wang J. B.,
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447 http//www.jb.man.ac.uk/pulsar/glitches/gTabl
e.html
Figure 1. The 2011 glitch of PSR J06301036. (a)
Variations of rotational frequency relative to
the pre-glitch solution. (b) An expanded plot of
frequency derivative where the mean post-glitch
value has been subtracted from the post-glitch
data.