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

;