Transcript Black Hole - bao.ac.cn
Zhen Yan, Zhi-Qiang Shen, Xin-Ji Wu On behalf of the Shanghai 65m Radio Telescope Team
Introduction to pulsar observation Introduction to SH-65m radio telescope
Four low frequency Receivers of SH-65m
The radio environment at SH-65m
Tentative pulsar observations with SH-65m Prospects of pulsar observations with SH-65m Conclusion
Clock on the sky Ultra-condition lab in the universe
Pulsar
Detector of ISM
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% t β T G N B δ α dimensionless loss factor, sys pol threshold signal-to-noise ratio, system temperature, telescope gain, number of polarizations, observing bandwidth, integration time, effective duty cycle.
New built 65-m in diameter fully steerable radio telescope located in Song Jiang district of Shanghai city Phase of the SH-65m project Funded in 2008; Started manufacturing in 2009; its 1 st 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
L S X C Freq-R
GBT
1.15-1.73
SEFD Freq-R SEFD Freq-R SEFD Freq-R SEFD 10 1.73-2.6
12 3.95-5.85
10 8.00-10.1
15
Effelsberg
1.27-1.45, 1.59-1.73
20,19 2.20-2.30
300 5.75-6.75
25 7.9-9.0
18
Parkes
1.2-1.8
31 2.2-2.5
25 4.5-5.1
61 8,1-8.7
170
Lovell
1.25-1.50, 1.55-1.73
36,65 ---- ---- 6.0-7.0
80 ---- ---- System Equivalent Flux Density (SEFD):
SEFD
2
k T B sys A e
SH65m
1.25-1.75
31 2.2-2.4
≥31 4.0-8.0
28 8.2-9.0
≥38
Backed: Pulsar Digital Filter Bank (PDFB4) from ATNF
Under the kind help of YNAO & NAOC
Incoherent de-dispersion
Maximum bandwidth 512MHz
S-band & X-band observations
S-band: band width ~150MHz used X-band: band width ~350MHz used
Pulsars including normal pulsars and millisecond pulsars
[email protected], Ob: S-band, t int ~3min
[email protected], Ob: S-band, t int ~15min
[email protected], Ob: S-band, t int ~18min MSP
DM=370, Ob: S-band, t int ~15min
[email protected], Ob: X-band, t int ~5min
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 bandwidth [email protected]
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)
Yellow
：
discovered by 1.4GHz survey Black
：
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 4 th power of observation frequency; weaker scintillation
the DM of these pulsars are very large (>900 pc cm −3 ) [email protected]
GBT search 27 bright γ-ray unassociated source ， 3 new pulsar discovered （ all of them are binary ） !
Globular clusters, which are found in the halo the less dense of a galaxy, contain considerably more stars and are much older than 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 undiscovered.
Milky Way , with perhaps 10 to 20 more still ~200 pulsars have been discovered in Globular clusters by now. Most of these pulsars are recycled pulsars (P<50ms)
By now, 5 pulsars have been discovered in the galactic center. (Johnston et al., 2006, Deneva1 et al.,2009) Pfahl & Loeb Sgr A* .
（ 2004 ） predicted that there are at least 100-1000 pulsars circle 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
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
--------------------------------------------------------------------------- # 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 ----------------------------------------------------------------------------
Pulsars with giant pulse —————————————————— PSR P (ms) S1400 (mJy) —————————————————— B0531+21 33 14.00
B1937+21 1.5 10 B0031-07 942 11.00
B0656+14 385 3.70
____________________________________ In order to study their radiation process (coherent curvature radiation, plasma ) Carried out at L / C band 30min/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 J1717 – 4054 J1727 – 2739 J1933+2421 J1944+1755 1.656 60 3 0.887 >95 54 1.293 52 (3) 1.6
0.814 80 25.9
（ 400MHz ） 1.997 60 40 （ 400MHz ） J1946+1805 J1853+0505 0.441 55 10 0.905
73 1.5
--------------------------------------------------------------------------- Observe at L&C band 2 hours/pulsar, twice a month Wang et al., 2007
Pulsars with mode change -------------------------------------------- # NAME P0 DM S1400 --------------------------------------------------------------- 1 B0329+54 (s) (cm^-3 pc) 0.714520
26.83
(mJy) 203.00
2 3 B0355+54 B1937+21 0.156382
0.001558
57.14
71.04
23.00
13.20
4 5 6 7 8 B1822-09 B2319+60 B0031-07 B0809+74 B0823+26 0.769006
2.256488
0.942951
1.292241
0.530661
19.38
94.59
11.38
6.12
19.45
12.00
12.00
11.00
10.00
10.00
9 B1237+25 10 B0818-13 1.382449
1.238130
9.24
40.94
10.00
7.00
---------------------------------------------------------------- L&C band 30min/pulsar, twice a month
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 month Long term monitoring. The longer the better.
GBT have detected the scintillation of PSR B0329+54 at 15GHz (private discussion) Wang et al., 2005 Lorimer & Kramer 2005
.
Yan et al.,2013 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.
Pulsar will be one of important scientific targets of SH-65m Some 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!