Pulsar Studies at Urumqi
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Pulsar Studies at Urumqi
Na Wang
Urumqi Observatory, NAOC
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History of Urumqi Observatory
Nov 1957: Founded, Urumqi Satellite Observation Station, Chinese Academy Of Sciences (CAS)
Oct 1987: Urumqi Observatory, CAS
Apr 2001: Urumqi Observatory, National Astronomical Observatories of CAS
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The Nanshan Station of Urumqi Observatory
• Built in 1993 as a VLBI station• 76 km to the south Urumqi• Altitude: 2080 m• On Tianshan Mountain, called
Nanshan
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0.001s 0.01s 0.1s 1s 10s
~1750 known, Galaxy, period ~ 1s
MSPs(~ 0.003 s): Binary, recycled, stable
NASA/GSFC; Walt Feimer/Allied Signal
Pulsars in brief
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Pulsar timing systemat Urumqi
PCI-DIO-32HS:Data card
PCI-DIO-96:Control card
GPIB: Start time
Center Frequency:1540 MHzTotal Bandwidth: 320 MHzFilterbank: 2x128x2.5 MHz
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• Glitch & Timing noise• Proper motion • Scintillation: DISS & RISS• Emission & single pulse• Transient source• Searching
• New backend• 80m• Application: GW, navigation & time keeper
Future
Work done at Urumqi
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Glitch & Timing Noise Study
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• For the slow glitch, there was a continuous increase in frequency for about 300~d followed by a return to the initial state for the next 500~d.
• Associated with the spin-up process is a decreasing slow-down rate (increasing ) which lasted 120~d with maximum
. The slow-down rate then decayed to approximately the pre-glitch level within 220~d.
• The fractional changes in frequency and frequency derivative before and after the slow glitch are and
respectively.
Urumqi: Detected a slow glitch in PSR B1822-09 (J1825-0935)
9/ 31.2(2) 10
15 2~ 3 10 s
3/ 1.9(1) 10
Similar glitches were also observed in PSR B1822-09 by Shabanova & Urama (2000)
Unusual glitch behaviours of two young pulsars
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• Significant cubic terms with opposite signal are present in the pre- and post-glitch data, suggesting a sign change in at the time of the glitch.
• The jump in at MJD 52220 has the reversed sign of before and after the glitch. There was little or no change in at the time of the glitch.
Detected one glitch in PSR J1835-1106
Zou, W. Z.; Wang, N.; Wang, H. X.; Manchester R. N. et al. 2004, MNRAS, 354, 811
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Observations of Six Glitches in PSR B1737-30
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Zou, W. Z.; Wang, N.; Manchester, R. N.; Urama, J. O.; Hobbs, G.; Liu, Z. Y.; Yuan, J. P.: MNRAS, accepted.
Observations of Six Glitches in PSR B1737-30
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n= -3(1)
Observations of Six Glitches in PSR B1737-30
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Updated rotational parameters
Residual: few hundred usPeriod accuracy: 0.1ns or better
Pulsar timing at Urumqi Astronomical Observatory:
observing system and results
Wang, N.; Manchester, R. N.; Zhang, J.; Wu, X. J. et al.: 2001, MNRAS, 328, 855
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Glitch Model:
ttQtt pdg )]/exp(1(1[)()( 0
pdd tt )/exp()(
Fractional decay Q = △νd/ △νg
Size △ν/ν=10-6
time constant τd=400 d
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◇ Amplitude in ΔP and
agree with our observation◇ In agreement with the Crab pulsar glitch:
◇ Correlation in sign
0P 0pP
pP
0pP
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Zou, W. Z.; Hobbs, G.; Wang, N. ; Manchester R. N. et al.: 2005, MNRAS, 362, 1189
Timing measurements and proper motions of
74 pulsars using the Nanshan radio telescope
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Projected directions of the proper motions for the 74 pulsars in our sample relative to the Galactic Plane
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20/25
Analyzed timing noise for 100 pulsars, to study the effect of timing noise to the accuracy of pulsar position measurement
White noise Red noise
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拟投MNRAS Long term monitoring of RRAT 1819 - 1458• RRATs are discovered in 2006• 11 known, 3pdot • Our observations started from 2007, 174pulses
( a )宽爆信号 ( b )窄爆信号 ( c )双峰脉冲 ( d ) RRAT 脉冲和地面干扰。
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RRAT1819 - 1458: timing residual of the observed 174 pulses.
Zhao, C. S.; Esamdin et al, 2009, MNRAS, in preparing
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Long-term scintillation observations of five pulsars
at 1540 MHz Observe every 9 d, 2001 Jan – 2002 Jun
2 - 6hr , 2 - 4min sub-integration
Pulsars : PSR B0329+54
PSR B1823+26
PSR B1929+10
PSR B2020+28
PSR B2021+51
Wang, N.; Manchester, R. N.; Johnston, S.; Rickett, Bet al.: 2005, MNRAS, 358, 270
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Dynamic spectra of PSR B0329+54
DM = 26.8 pc cm-3
Dist = 1.06 kpc
3 hr obs.
Δtd ~ 10-30 min
Δνd ~ 5-15 MHz
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Secondary Spectra,Two dimensional FFT of dynamic spectrum
3
s
r
V
D
d
dt
2222
t
s
fVc
Df
Observing the structure of central image !
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Modulation indices
Observed > prediction !!
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Frequency dependence of DISS parameters
a. Bhat, Rao & Gupta 1999b. Gupta, Rickett & Lyne 1994c. Stinebring, Fainon & Mckinnon 1996d. Our results
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Kolmogorov Spectrum β=3.67
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Daily Observations of Interstellar Scintillation in PSR B0329+54
Obs: Mar 12—31, 2004
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Daily Observations of Interstellar Scintillation in PSR B0329+54
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Structure Function
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Cross correlation
Wang, N.; Yan, Z.; Manchester, R. N. et al.: 2008, MNRAS, 385, 1393
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Other projects
• Searching for Radio Pulsars in 3EG Sources at Urumqi Observatory
Dong, J.; Wang, N.: 2006, ChJAS, 6b, 294
• Monitoring of Pulse Intensity and Mode Changing for PSR B0329+54
Liu, Z. Y.; Wang, N.; Urama, J. O. et al: 2006, ChJAS, 6b, 64
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Timing Noise
Yuan J. P. et al, 2009, MNRAS, in preparing
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Threads: • setting the digitizer
parameters• data sampling• data unpacking & checking
time synchronization, folding of channel data
• de-dispersion, display• save data to disk• communicating with
telescope computer
Block Diagram for Online Program
V1: Pulsar Timing Data Acquisition—PTDA , written in Visual C++, by N. WangV2:Pulsar Observing —POP , Linux version, fits, written in C, by Z. Y. Liu
Timing modeSingle pulse modeSearch mode
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Future
New back-end system• Digital filter-bank• Coherent de-disperse
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• 80m
• Freq : up to 22 GHz
• digital filter-bank
• Multi-beam
ABC Collaboration for Global Pulsar Monitoring (Australia , Britain , China)
A plan for 80m radio telescope
Gravitation wavePulsars as clock Deep space navigationPulsar monitoring
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49°10′
34°20′
73°33′
96°22′