zhen yan, zhi-qiang shen, xin-ji wu on behalf of the shanghai 65m radio telescope team
TRANSCRIPT
PULSAR SCIENCE WITH SHANGHAI 65M RADIO TELESCOPE
Zhen Yan, Zhi-Qiang Shen, Xin-Ji Wu
On behalf of the Shanghai 65m Radio Telescope Team
OUTLINE
Introduction to pulsar observationIntroduction to SH-65m radio telescope
Four low frequency Receivers of SH-65mThe radio environment at SH-65m
Tentative pulsar observations with SH-65m Prospects of pulsar observations with SH-65m Conclusion
THE CHALLENGE OF PULSAR OBSERVATION
Weak pulse signal with accurate period
• Average flux density 0.8mJy @1.4GHz （ Statistic on 908 pulsars ， 1 Jy =10−26 W m−2 Hz−1 ）
• Duty cycle < 10%Observation sensitivity
α dimensionless loss factor, β threshold signal-to-noise ratio,
Tsys system temperature, G telescope gain, Npol number of polarizations,
B observing bandwidth, t integration time, δ effective duty cycle.
INTRODUCTION TO SHANGHAI 65M RADIO TELESCOPE
New built 65-m in diameter fully steerable radio telescope located in Song-Jiang district of Shanghai city
Phase of the SH-65m projectFunded in 2008; Started manufacturing in 2009;its 1st phase will be finished in July 2013, four low frequency
receivers (L,S,C,X) have been installed.Will expand to Q-band (43GHz) in 2015 using active surface
system to make sure its efficiency
THE LOCATION OF SH65
THE RADIO ENVIRONMENT AT SH-65M
COMPARISON SH65M WITH OTHER TELESCOPES
GBT Effelsberg Parkes Lovell SH65m
LFreq-R 1.15-1.73 1.27-1.45, 1.59-1.73 1.2-1.8 1.25-1.50, 1.55-1.73 1.25-1.75
SEFD 10 20,19 31 36,65 31
SFreq-R 1.73-2.6 2.20-2.30 2.2-2.5 ----- 2.2-2.4
SEFD 12 300 25 ----- ≥31
CFreq-R 3.95-5.85 5.75-6.75 4.5-5.1 6.0-7.0 4.0-8.0
SEFD 10 25 61 80 28
XFreq-R 8.00-10.1 7.9-9.0 8,1-8.7 ----- 8.2-9.0
SEFD 15 18 170 ----- ≥38
2 B sys
e
k TSEFD
ASystem Equivalent Flux Density (SEFD):
TENTATIVE PULSAR OBSERVATIONS WITH SH-65M
Backed: Pulsar Digital Filter Bank (PDFB4) from ATNF
Under the kind help of YNAO & NAOC Incoherent de-dispersionMaximum bandwidth 512MHzS-band & X-band observations
S-band: band width ~150MHz usedX-band: band width ~350MHz used
Pulsars including normal pulsars and millisecond pulsars
A LARGER DM PULSAR-J0248+6021
DM=370, Ob: S-band, tint~15min
DIBAS-THE DIGITAL BACKENDSYSTEM FOR SH65M
Search mode One beam, dual polarization Up to 2 GHz bandwidth, depending on
the analog bandwidth available at the telescope
256, 512, 1024, 2048, 4096, and 8192 spectral channels
Full Stokes, summed polarizations, or Stokes I only modes
8 bit output width 800 MB/sec maximum output data
rate to disks on a clustered file system Online folding mode
Coherent-dedispersion & incoherent-dedispersion
Operate at 2 GHz [email protected]
BLOCK DIAGRAM
Analog to Digital Convert
Roach 2 Running Vegas or Guppi Fireware
10 GbE Switch
High Performance Computer running Vegas and Guppi software
Parallel File system based storage
(GTX-580 GPU)
THE ADVANTAGE OF C-BAND PULSAR SEARCH
Yellow： discovered by 1.4GHz surveyBlack： discovered by 430MHz survey
Low frequency is blocked by thick plasma around the Galactic center
lower galactic noise background, as the galactic noise is steeper power law
weaker dispersion effect, as the dispersion delay is in proportion with the square of observation frequency
weaker scattering, as the width of scattering broadening is in proportion of 4th power of observation frequency;
weaker scintillation
A SAMPLE OF PULSARS DISCOVERED BY PARKES-64M @6.5GHZ
the DM of these pulsars are very large (>900 pc cm−3)
UNASSOCIATED Γ-RAY POINT SOURCES
GBT search 27 bright γ-ray unassociated source ， 3 new pulsar discovered （ all of them are binary ） !
GLOBULAR CLUSTERS Globular clusters, which are
found in the halo of a galaxy, contain considerably more stars and are much older than the less dense galactic, or open clusters, which are found in the disk. Globular clusters are fairly common; there are about 150 to 158 currently known globular clusters in the Milky Way, with perhaps 10 to 20 more still undiscovered.
~200 pulsars have been discovered in Globular clusters by now.
Most of these pulsars are recycled pulsars (P<50ms)
ADVANTAGE OF GALACTIC CENTER PULSAR OBSERVATION WITH SH-65M
By now, 5 pulsars have been discovered in the galactic center. (Johnston et al., 2006, Deneva1 et al.,2009)
Pfahl & Loeb （ 2004 ） predicted that there are at least 100-1000 pulsars circle Sgr A* .
Compared with Parkes 64m C-band pulsar search, the sensitivity of our search is with higher sensitivity.
Higher frequency is the good choice when we want to find some new pulsars in the galactic central area. This is approve by following research work: A magnetar PSR J1745-2900 discovered only
3” from Sgr A* This pulsar has detected with large telescope
at 2.5GHz, 4.85 GHz, 7GHz, 8GHz, 14.6 GHz, 22GHz
But it can not be detected at 1GHz with GMRT and 1.5GHz with Lovell Telescope
MULTI-FREQUENCY OBSERVATION The multi-frequency integration
profile and flux density are important information for studying the pulsar radiation process
The high frequency (>4GHz) integration profile and flux density of almost all the pulsars have not been measured.
A project that measures the high frequency integration profile and flux density of a large sample (~60) of pulsars with SH65m will be carried out.
C-band (central frequency ~5GHz), for some strong pulsars, will expand to X-band
THE PULSAR CATALOG----------------------------------------------------------------------------# NAME P0 DM W10 S1400 (s) (cm^-3 pc) (ms) (mJy) ----------------------------------------------------------------------------1 B0329+54 0.714520 26.83 31.400 203.00 2 B0950+08 0.253065 2.96 20.600 84.00 3 B1933+16 0.358738 158.52 17.700 42.00 4 B2020+28 0.343402 24.64 15.800 38.00 5 B1929+10 0.226518 3.18 14.000 36.00 6 B1133+16 1.187913 4.86 41.800 32.00 7 B2016+28 0.557953 14.17 22.200 30.00 8 B2021+51 0.529197 22.65 29.400 27.00 9 B0355+54 0.156382 57.14 10.800 23.00 …….56 J1852-0635 0.524151 171.00 * 5.90 57 B1900+01 0.729304 245.17 23.000 5.50 58 B2106+44 0.414871 139.83 102.000 5.40 59 B0450-18 0.548939 39.90 36.800 5.30 ----------------------------------------------------------------------------
SINGLE PULSE OBSERVATION
Pulsars with giant pulse——————————————————PSR P (ms) S1400 (mJy)——————————————————B0531+21 33 14.00B1937+21 1.5 10B0031-07 942 11.00B0656+14 385 3.70____________________________________
In order to study their radiation process (coherent curvature radiation, plasma )Carried out at L / C band30min/pulsar, twice a month; or monitoring one pulsar for several hours
RRAT (rotating radio transient) Discovered recent years (2006)
————————————————————————————————RRAT P (s) DM (cm-3 pc) S1400 (mJy) 备注————————————————————————————————J1819-1458 4.263 196 3600 新疆 25 米 1.5GHz 已观测J1826-17 0.77 159 600 尝试 65 米能否观测到J1913+1333 0.92 175 650 尝试 65 米能否观测到————————————————————————————————
Pulsars with nulling phenomenon Candidates
---------------------------------------------------------------------------Name P(s) NF (percent) S1400 (mJy) --------------------------------------------------------------------------J1115+5030 1.656 60 3J1717–4054 0.887 >95 54J1727–2739 1.293 52 (3) 1.6J1933+2421 0.814 80 25.9 （ 400MHz ） J1944+1755 1.997 60 40 （ 400MHz ）J1946+1805 0.441 55 10J1853+0505 0.905 73 1.5----------------------------------------------------------------------------
Observe at L&C band2 hours/pulsar, twice a month
Wang et al., 2007
Pulsars with mode change
L&C band 30min/pulsar, twice a month
---------------------------------------------# NAME P0 DM S1400 (s) (cm^-3 pc) (mJy)----------------------------------------------------------------1 B0329+54 0.714520 26.83 203.002 B0355+54 0.156382 57.14 23.003 B1937+21 0.001558 71.04 13.204 B1822-09 0.769006 19.38 12.005 B2319+60 2.256488 94.59 12.006 B0031-07 0.942951 11.38 11.007 B0809+74 1.292241 6.12 10.008 B0823+26 0.530661 19.45 10.009 B1237+25 1.382449 9.24 10.0010 B0818-13 1.238130 40.94 7.00-----------------------------------------------------------------
Pulsar in the Galactic center (C-band, ~1hour/pulsar)MSPs selected from NanoGrav,
EPTA & PPTA source list (L-band,~30min/pulsar)Pulsar with glitch phenomenon,
such as Crab et al (C-band, >30min/pulsar). twice a monthLong term monitoring. The
longer the better.
PULSAR SCINTILLATION AT C-BAND
Lorimer & Kramer 2005
Wang et al., 2005
GBT have detected the scintillation of PSR B0329+54 at 15GHz (private discussion)
PULSAR ASTROMETRY WITH VLBA PLUS SH-65M
For pulsars located at high declination (DEC>45 deg), the resolution in right ascension (RA) will be affected because of the limited length of projected baseline along East-West direction of VLBA . The partition of some Chinese antennas will lengthen the baseline twice times in East-West direction and make the UV-coverage of observation of source much better..
Yan et al.,2013
CONCLUSIONSPulsar will be one of important scientific
targets of SH-65mSome tentative pulsar observations with SH-
65m have been done. And good results have been obtained.
SH-65m can play an important role in the fields of pulsar research, such as pulsar searching, nulling, giant pulse, RRAT, pulsar timing, astrometry plus VLBA et al.
We are looking for cooperators who are interested with about fields. Welcome to use our telescope!
Thank you!