A Commensal FAST Drift-Scan Survey
Di Li· 李菂Chief Scientist, Radio Dept., NAOC
Deputy Manager, Deputy Chief Engineer, FAST
FAST
the waking Giant
Timeline
•Project Approval: Dec., 2007 •Commence Construction: March, 2011 •Openning ceremony: Sep. 25, 2016
•19 beam L-band array: to be delivered in Dec., 2016 •Backend upgrade (for commensal survey): • under development, to be expected in Spring of 2017
•Commissioning: 2016 - ~2018 •Operation: ~2019
Outline๏ FAST Concepts and Innovations
“mega”-science: uniqueness and limitations
๏ Early Science Preparation a. Galaxy and Cosmology b. Pulsar, gravitational wave, and FRBs c. ISM and Star Formation
๏ A Commensal Drift-Scan Survey Necessity, advantage, and challenges
Five-hundred-meter
Aperture Spherical radio
Telescope (FAST)
FAST (2016.5)
Arecibo
100 m
300 m
500 m
GBT
100meters
SiteActive Reflector
Feed supportMeasurementsReceivers
Observatory
Site
Exploration
Drainage
Earth work
Active Reflector
Disaster prevention
Main cable net
Elements
Winches
Tension monitoring
Tower
Capstan
AB-rotator & Stewart
Cables
Mark stone
Laser total station
Photogrammetry
Field bus
Optical fiber
Observatory building
Computing center
Observatory
Feed support
MeasurementsReceiversReceivers
Backend
6 Subsystems
667,230,000 RMB 1,149,590,000 RMB
IIIIIIIV
cI. Active Reflector: Cable Mesh
II. Measurement and Control
II. Measurement and Control
Measurement 1)Anchor Grids
Anchor points: 5cm+0.5" Baseline: 1mm Time accuracy: 10ms
(2)Feed Cabin Supporting tower: 2cm Cabin Initial Position: 2mm Cabin dynamic measurement: 3mm Cabin dynamic control: 10mm Frequency: 5Hz
(3)Primary Panels Actuator anchor point: 2cm Cable mesh system anchor point: 2cm Panel connecting nodes: 1.5mm Nodes dynamic measure and control: 2mm Frequency: 0.0017Hz
FAST Optics
III. Focal Cabin
7setsoffrontend�
No.$ $ Frequency$range(a)$(MHz)$
Number$ of$Beams$
Polarization$Mode(b)$
System$Temperature(c)$
1$ 70D140$ 1$ RCP$&$LCP$ 1000$2$ 140D280$ 1$ RCP$&$LCP$ 400$3$ 270D1620$ 1$ RCP$&$LCP$ 150$4$ 560D1020$ 1$ RCP$&$LCP$ 60$5$ 1100D1900$ 1$ RCP$&$LCP$ 25$6$ 1050D1450$ 19$ X$&$Y$linear$ 25$7$ 2000D3000$ 1$ RCP$&$LCP$ 25$
$
35
IV. Receiver System
Constraints on FAST• Slewing time: 1.5min - 10min
• Beam and FOV: 3’ in L-band, ~26’ with 19 beam
• Drift Scan: only feasible mode for large surveys in early years
• Sky coverage: DEC -14º to 66º ( -1º to 52º with full gain)
• Confusion limited: in 1 s @ ~1 mJy
• VLBI/Timing: moving phase center?
FAST is slow.
Outline๏ FAST Concepts and Innovations
“mega”-science: uniqueness and limitations
๏ Early Science Preparation a. Galaxy and Cosmology b. Pulsar, gravitational wave, and FRBs c. ISM and Star Formation
๏ A Commensal Drift-Scan Survey Necessity, advantage, and challenges
70MHz~3GHz
a)Hydrogen hyperfine structure 21cm line
b)Pulsars c)Molecular lines, masers, radio continuum
Observablescontinuous coverage
MOST Key Program (973) 2012.2.14-2016.8.30 Observers lead, collaborating with theorists, modeling experts, and instrumentalists, work toward a concrete definition of FAST key programs and early science goals.
1. Pulsar Observations and Theories (Xu@PKU) 2. From Atoms to Star: ISM and Star Formation (Li@ NAOC) 3. Galaxy Evolution and Structures (Zhu@NAOC) 4. Cosmology and Dark Matter (Zhu@BNU) 5. Radio Spectroscopy and Masers (Wang@NJU) 6. Multi-beam System and VLBI (Jin@NAOC)
MOST Key Program Timeline
2011
FAST Construction
2012 2013 2014 2015 2016 2017
FAST OperationFAST Project
973 项 目 计 划
Survey Data Aggregation
Key Algorithm Development
Discoveries: Pulsar, Galaxies, Masers ...
Astrophysics
FAST Early ScienceFAST Science
FAST Normal Observation
Synergy!
“Radio Frontiers” Highlights
Feb. 2012 – Aug. 2016
• Science Outputs
• High Impact Results
– Published 339 papers in all (270 in SCI, 8 in EI) – Organized 30 international conferences or workshops (HI, pulsar search, etc.) – 62 invited talks at international conferences – International Leadership: SKA Board Member, SKA SWG
Chair, ATNF Steering Committee, Breakthrough Listen Advisory Committee, etc.
– Direct Test of Cosmic Acceleration (Yu, Zhang & Pen 2014) – Finding New Type of Megamasers (Wang et al. 2014) –Most Comprehensive Statistical Research of Pulsar Glitches
(Yu et al. 2013) – Complete molecular dynamic structures in Taurus (Li et al.
2015 – Discover New Millisecond Pulsars (Pan et al. 2016)
ARECIBO
AL
MA
EFFELSBERG ATCA JVLA GMRT …
支持竞争使用国际一流射电望远镜
IRAMJCMT
北京师范大学 天文系(于浩然,张同杰等) HI 21 absorption line system在不同时间内测量同一个中性氢云的21cm吸收线的谱线移动->红移变化->速度变化->最终得到宇宙不同时刻的加速度Sandage-Loeb (SL) effect
量级~ mm/s/yr—异乎寻常地小!Time baseline: t_0 (5年或者10年)观测要求: (1). Spectral resolution: ~ kHz(2). Frequency stability ~ 10^{-11} over 10 yr
a)
Two New Pulsars!➡ 正⽂级别 1
- 正⽂级别 2 ‣ 正⽂级别 3
正⽂级别 4
正⽂级别 5
Pan, Hobbs, Li et al. 2016 MNRAS
Pan, Hobbs, Li et al. 2016, MNRAS 中国工作的学者主导发现新射电脉冲星
• Max Planck group will soon published new timing results
• GBT started reprocessing of GC surveys (S. Ransom)
b)
IRAM 30M SiO 2-1 (v=3) emission line in NGC
1068 with 26 hours observation using
▪ Selected as highlight: Nature Communication 2014.11
▪ 2014 Top Ten Highlights of Chinese Astronomy
Discovery Two New Kinds of Megamaser c)
FAST Early Sciences (ES)Main Challenge Error budget – 10 mm Distance/Range- 150m/300m
Sci-Tech Considerations Low frequency point sources signature
Build an Ultra-wide Band Receiver Drift-scan survey!
Li, Nan & Pan 2012, IAUS291
UWBR: dream came true!
Built, installed, commission started.
2012于加州理工3年合作研发
2016于工地9月14-18号中秋假期
接收机组连夜奋战
Key ES Programs
a)HI Emission/Absorption Survey, Disk coverage and M31-M33
b)Pulsar Search in Nearby Galaxies and Globular Clusters M31 is out of Arecibo Coverage
c.1)OH Mega-Maser Search FAST 2.3 X Arecibo Sky; growing IR Galaxy catalogues
c.2)Orion Spectral Line Survey Orion is out of Arecibo Sky; Herschel Orion Source Model
Radio Detection of cosmic carbon structures?
Planetary Nebular: C60和C70 Cami et al. 2010,
SCIENCE 329, 1180
MOST Key Program Timeline
2011
FAST Construction
2012 2013 2014 2015 2016 2017
FAST OperationFAST Project
973 项 目 计 划
Survey Data Aggregation
Key Algorithm Development
Discoveries: Pulsar, Galaxies, Masers ...
Astrophysics
FAST Early ScienceFAST Science
FAST Normal Observation
Synergy!
Outline๏ FAST Concepts and Innovations
“mega”-science: uniqueness and limitations
๏ Early Science Preparation a. Galaxy and Cosmology b. Pulsar, gravitational wave, and FRBs c. ISM and Star Formation
๏ A Commensal Drift-Scan Survey Necessity, advantage, and challenges
Actuators - Cables - Rods Constraints
Shadowing Extension: +/- 0.5m Fatigue: >100k stretches Tension: 2-10 tons Failure rate: ? A
n Actuator
Tripyramid backframe support
Actuator
Light- and corrosion-resistant aluminum construction
Re�ector panel
Support grid
500 m
305 m
FAST
Arecibo
Dish
Central sensor array with cable suspension
Supporttower
Natural karstdepression
Natural karstdepression
Maximum movementis roughly 47 cm.
300 m
Radio astronomy writ large The world’s largest radio telescope, China’s
new Five-hundred-meter Aperture Spherical radio Telescope (FAST), will gather radio signals from the cosmos to catalog pulsars; probe gravitational waves, dark matter, and
fast radio bursts; and listen for transmissions from alien civilizations.
A “bowl within a wok”FAST’s signature innovation is a system that pulls a section of the dish as much as 300 meters across into a parabola to focus cosmic radio waves on receivers. Provided a glitch is resolved, the parabola’s position can be shifted in real time to keep it trained on an astronomical object as Earth rotates.
Bigger is betterFAST has more than twice the collecting area of the world’s second largest radio telescope, the Arecibo Observatory in Puerto Rico, enabling it to study fainter and more distant objects.
Snug fitFAST planners studied some 400 karst depressions in southwestern China before deciding Dawodang was just right for cradling the telescope’s massive dish.
Tuning the radio dial To deform the reflector and create the bowl-within-a-wok effect, 2225 actuators, essentially high-tech winches, are anchored into rock beneath the dish’s 4450 triangular reflector panels. A 300-meter-diameter deformed section can be trained on objects 26° from the zenith; smaller sections can view the skies up to 40° from the zenith.
A gentle tugThe actuators pull on tie-down cables connected to the dish’s supporting mesh to form the parabola. The natural springiness of the supporting mesh restores the dish’s spherical shape when the actuators relax the tension.
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Drift (sidereal):漂移扫描
?
~200 days for one pass
Drift (sidereal):多波束漂移扫描规划
The Key Challenges2457 radio pulsars
➡ Parkes 1407 - Parkes Multi-beam Survey;Swinburne Mid-latitude Survey;
Parkes High-latitude Survey ➡ Arecibo ~150
- PALFA ➡ Fermi follow-up ~200
1.How to search for pulsars with drift scans? 2.How to realize an effective, simultaneous surveys of
pulsars, HI galaxies, Galactic HI, FRBs, and SETI?
(COMMENSAL: unprecedented)
Drift-scan surveys not as productive!
Commissioning + Upgrade➡ Multi-backend ➡ Noise-cal strategy ➡ baseband ➡ scan pattern ➡ RFI mitigation ➡ Voltage data ➡ Pointing, tracking, beam characterization, data
archiving, pipeline
How to realize a first large-scale commensal survey of pulsars, HI, and transients?
The Knowledge Gap
The “Millennium" Simulation
Springel et al. 2006
ASKAP-FAST HI Gals Survey3.8π sky survey
• 1201 ASKAP fields – 9600 hrs • 110 FAST driftscans – 2700 hrs • 0 < z < 0.26 (<z>=0.05) • 500,000 galaxies vs ALFALFA (15000 galaxies)
• Velocity resolution 4 km s-1
• 30”-3’ resolution
Matching Optical Surveys?
Credit: Lister Staveley-Smith (UWA) + Di Li (NAOC)
a)
INcrease gaseous galaxies x10
FAST Cosmological Studies
Yue, Li, Gu, Wu, Zhao, & Zhang ... 2016, in pep.
Baryon Acoustic OscillationDark Energy EoS
a)
The Cosmic Web
Credit: A. Popping (UWA)
a)
FAST Drift Scan SurveysDrift scan whole FAST sky (~58% whole sky)
~2300 pulsars, 300 MSP +5year timing =>
3 x improvement over current IPTA
0 5 10 15 2010−16
10−15
10−14
10−13
10−12
Tobs (yr)
h c
IPTA White NoiseFAST New Pulsar White NoiseFAST New Pulsar Red NoiseFAST New Pulsar Red Noise+JitterIPTA Red NoiseFAST+IPTA Red Noise+Jitter
Yue et al. 2013 and Yue et al. in prep.《RAA》
b)
Dark Matter vs PulsarsPAMELA, Fermi-LAT, AMS-02, et al. E>10GeV Positron Fraction increases along with the energy increasing
L. Accardo et al. (AMS Collaboration) PRL 113, 121101 (2014)
AMS02
CRs model
Dark Matter Annihilation Or High Energy Radiation of Pulsars ?
A Pulsar Origin of Positron Excess
The injection CR positrons (left) and the resulting positron fraction (right) from the sum of all nearby pulsars throughout the Milky Way. Testing validity of method by using 3 nearest known pulsars. Additional component of e+/e flux from local pulsar sources can set stringent constraints on dark matter interpretation.
Wang, Li, and Bi et al. 2016 in prep.
Globular Clusters
Zhang, Hobbs & Li et al. 2016, RAA
NGC7078�
NGC6517�
NGC6254�
NGC6402�
Num
ber of Drifts
1285-1600 MHz
970-1285 MHz
500-850 MHz
16
20
34
UWBR
Continuous data stream in timeBeam forming by weighted Fourier transformRFI rejection by utilizing time domain information
Extra-galactic PulsarsBahcall, Rees & Salpeter 1970
Bachetti et al. 2014: M82, Chandra, 1.37s
Manchester et al. 2000 LMC, SMC: now > 15 pulsars, also X-ray
M33: None M31: ?
50-80 normal pulsars detectable by FAST (Smits et al. 2009) Giant pulse Credit: Crawford, Cordes & Li LOW HIGH Freq(MHz) 560 1295 BW (MHz) 580 680 Nchan 5220 5850 T_drift (sec) 33 14
LOW: one detection every 0.7 to 2.0 minutes HIGH: one detection every 180 to 540 minutes
Yue, Li, Nan 2013
Fang et al. 2014
They re-examine the observational data, particularly in the X-ray / radio bands and pulsar DM, in order to determine whether it is possible for a substantial fraction of the Galaxy’s baryons to exist in a hot halo. Extragalactic pulsar DM may provide the crucial distinguishing evidence.
• Extended Adiabatic Halo: MB• Cuspy Halo: NFW• Local Model: DISK
LMCSMC
a+b)
A simple ‘double drift’ survey would put tight constraints on the timing and power of reionization, and
discover between 5 and 10 new gas-rich local group dwarfs
←24 local group simulations →
FAST
yie
ld (
var.
assu
mpt
ions
)a+c)
cf. Rees 1986 Grebel and Gallagher 2004 Weisz et al. 2014
Reionization Effect
ISM Inventory
EGRET [CR/H-nuclei]interaction
-(HI+X*CO)Grenier et al. 2005 Science
IRAS [IRAS–(HI+X*CO)]
Planck DustOpacityvs(HI+X*CO)
Dark Gas “暗气体”
Dark Gas SurveyHeiles & Troland, 2003, ApJ • Arecibo telescope • 79 sources, 286 citations
FAST: 800 quasars in 5 years
• Z17 pattern • 4 hours on each source, total of 400 hr per year
Publication: 1, Li et al. 2015, Quantifying Dark Gas
2, Tang et al. 2016 accepted, Physical Properties of CO-dark Molecular Gas Traced by C+
3, Tang et al. 2016 in prep, Pilot OH Survey along Sightlines of Galactic Observations of Terahertz C+
Li et al. 2015 Heiles & Troland 2003
PRIMO“ ”
Dark gas absorption survey
INcrease sample x10 times
c)
Fast Radio Burst
17 FRBs’ location, 9 red spots are the FRBs in FAST.(FRB121102, FRB130628, FRB110523, FRB110703 , FRB130729 , FRB130626 , FRB010621, FRB140514, FRB110220).
Li et al. 2016 RAAFAST 19beam: 5 FRB/1000hrs
Drift Scans
1)Anchor Grids Anchor points: 5cm+0.5" Baseline: 1mm Time accuracy: 10ms
(2)Feed Cabin Supporting tower: 2cm Cabin Initial Position: 2mm Cabin dynamic measurement: 3mm Cabin dynamic control: 10mm Frequency: 5Hz
(3)Primary Panels Actuator anchor point: 2cm Cable mesh system anchor point: 2cm Panel connecting nodes: 1.5mm Nodes dynamic measure and control: 2mm Frequency: 0.0017Hz
2016-2017 UWB: high latitude drift 2017-2019 19 beam-L band: all sky two drifts ~500 pulsars; 100K galaxies; 1 billion-Voxels HI Map ~20 FRB: confirm counter part?
COMMENSAL
多项同时巡天
a+b+c)
FAST-LIGO-VIRGO
LIGO-Fxxxxx, VIR-0495D-xxx Memorandum of Understanding between FAST and LIGO and VIRGO regarding
mutual follow up observation of potential gravitational wave events
Ferm
i Sources in
FA
ST Sk
y
• 射电-高能脉冲星分布成协性统计
• HXMT & FAST 开展对未认证源的多波段联合观测
• X-ray、射电多波段鉴别双星、AGN、Nebula、FRB、超新星遗迹等源属性
• 多波段联合监测光变时延、Recycled MSP模式变换、Glitch、TOA相位差等演化属性
41 MSP Cands 39 Nomal_PSR Cands
FAST - HXMT Synergy
➡ East Asia Core center of Astronomy (EACOA) Fellow: $5000/month; two host during tenure
➡ National Astronomical Observatories of China (NAOC) Fellowship
➡ Big Science Center-FAST Fellowship • Senior fellowship (2weeks - 1month) • Key Staff: ~1year • Postdoctoral fellowship: 2-3 years @ 2/year
➡ Chinese Academy of Sciences (CAS) Fellowship (PIFI etc.)
➡ Talent program: ~$400 ~ 500 K startup grant
Opportunities
SouthAfrica - China SKA Collaboration?
•Sept. 1972: Joe Taylor’s proposal to NSF: A High Sensitivity Survey to Detect New Pulsars ($33,557) 2 × 32 × 250 kHz filter bank receiver + Modcomp II/25 “mini-computer”
• The Arecibo Legacy Fast ALFA Survey (ALFALFA) 2005-2012, 2pass-drift scan, 7000 d2 , 15000 HI Galaxies, 14 PhD
ARECIBO Landmark Science
Current StatusOfficial first light: Sep. 25, 2016
➡ Commissioning goals: 2000 m2/K, 6 hr tracking, 10” pointing ➡ Major contracts: actuators, control systems, etc. yet to be closed. ➡ Operation fund: $0 (to be determined after a successful project
review). Stop-gap funding from CAS: ¥40M ➡ Data center: non-existant, to be funded by operational fund. ➡ Operational mode (only a suggestion from the project scientist):
~50% large surveys, ~50% PI-driven open time ➡ Science planning: welcome suggestions made to the CAS science
advisory panel (Chair: Wu, X.P.) and the FAST Chief Scientist: (Nan, R.D.)
South Africa - China➡ MeerKat + FAST ➡ Personnell Exchange ➡ Infrastructure
ROACH2 CRANE
Roach2 FDB-1
1 Virtex-6 SX475T FPGA 2 Virtex-6 4
ADC 3Gsps 8bit 550 Msps12 bit etc FAST3212 ADC 3Gsps12bit
8 10GbE 12 10GbE
4 x 36 * 2M QDR II+ SRAMs 288M QDR extensible
A single 72-bit DDR3 RDIMM slot 16G DDR3-SDRAM extensible
;
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