VLBI Activities in China：an update

Zhi-Qiang Shen

Shanghai Astronomical ObservatoryChinese Academy of Sciences

11th East Asia VLBI Workshop 20184-7 September 2018, PyeongChang, Korea

Major Facilities for RA in China

Kashi 13m

Sanya 13m

Jilin13m

Legacy CVN

Newly built big dish

VGOS

CDSN

Current VLBI facilities in China

Luonan 40m

Activities at each site FAST

Kunming

Urumqi

VGOS

Shanghai

FAST - VLBI system installed

Test observations in planning

• L band with Sh, Ur

• Drift scan mode

• Tracking mode

• First light in 2019?

H-maser ROACH-2 Mark 6

Kunming - VLBI system updated

Updated to CDAS2

DBBC2+MARK6

New H-maser

FlexBuff coming soon!

S X C(new)

Frequency range

2150~2450MHz

8200~9000MHz

4000~8000MHz

Polarization

L&R L&R L&R

LO 2000MHz 8100MHz optional

Tsys 50K(Room TEMP.)

70K(Cooled)

45K

Efficiency ~60% ~45% ~50%

Good EM env (4040—7500 MHz)

Urumqi – updated to 26m

Dish 25m -> 26m

New Q-band Rx

30 GHz~50 GHz

Tsys < 65K

DBBC2 backend

Test observations in late of 2018

Tsys measurements LCP & RCP

Q-band receiver installing

25 m

VGOS – NTSC+SHAO

13m diameter antennaVery high slew rates

12° /s in azimuth 6° /s in elevation

Frequency range 1.2 ~ 9 GHzEfficiency > 50%Bandwidth: 1GHz *4Commissioning since 2017

Sheshan VGOS

Fringes Dec. 2017

Tianma VGOS

Sh

Shanghai – update

FlexBuff installed 240 TB e-VLBI & local disk

e-VLBI up to 2Gbps under testing

EAVN 2018B open useCE-4 VLBI trackingrelay-sat in orbit

Shanghai – VLBI Sci & Tech workshop

(18-19 May, 2018)

More than 100 participants from 20+ institutes and universities.

40+ presentations: covering VLBI facilities, astrophysics, astrometry, geodesy, deep space applications and technical development.

Related scientific outputs AGN studies

Pulsar astrometry, Survey

Lunar missions

Study the compact structure in M81*

Tm

Ur

Sh

6.1km

~3250km

VLBI detected jet component of M81* with CVN at X-band (Kawaguchi et al. 2015)

0.1 mas

The first VLBI Image of M81* at 3.4 mm with VLBA. (Jiang et al. 2018)

Peak=45.3 mJy/beamRMS=0.34 mJy/beamDynamic range ~ 130

s ∝ λ0.88

Among 3321 sources (red+green) in the ecliptic plane, 556 sources detected (green).

VLBI Ecliptic Plane Survey (VEPS)

(Shu et al. 2017 )

澳大利亚LBA干涉阵+昆明40米望远镜

~13 arcsec, ~45 arcsec ~1 mJy, compact and flat spectrum calibrators

LBA+KM40：@2.3GHz；

Li et al, 2018

Improve the parallax of J0437-4715 Measure Gdot combined with timing results

Detection of nearby calibrators for MSP

J0437-4715 with LBA+KM 40m

Pulsar Astrometry with VLBA+TM

NAME PSRJ P0 DM S1400B0458+46 J0502+4654 0.638565 s 42.19 cm^-3 pc 2.50 mJyB2334+61 J2337+6151 0.495370 s 58.41 cm^-3 pc 1.40 mJy

(Yan et al. )

pulsar parallaxes via relative astrometry (differential

astrometry) to get distances and transverse velocities

VLBI astrometry of white dwarf binary

system AR Sco with EVN and CVN

PM_ra = 11.44 ± 0.33 mas/yrparallax=8.37 ± 0.19 mas

(Jiang, Cui, et al. )

In collaborations with HartRAO, SHAO, UTAS etc.

Fringe test on April 18, 2017 (Hart26m-TMRT).

The first 24 h session already done on August 28, 2017!

K band Astrometry

Corr. @ SHAO

2Gbps K-band fringe Hh-T6!

Phase-reference results of CE-3 Rover

Target: Rover using the Lander as the Calibrator.

The accuracy of the relative position between Lander and Rover is ~1m (0.5mas).

Rover

Lander

AB

C

D

EE17

Future QTT110m

A 40-m RT at YBJ（Tibet）

Space VLBI

QTT110m

150 MHz – 115 GHz (1st phase upto 30 GHz)

Major Facilities for RA in China

Kashi 13m

Sanya 13m

Jilin13m

Legacy CVN

Newly built big dish

VGOS

CDSN

Current VLBI facilities in China

Luonan 40m

YBJ 40m

Space Millimeter VLBI Array

Main Scientific Objectives:• High-resolution imaging of emission structure surrounding super-massive

black hole (SMBH) to study

• SMBH Shadow (e.g. M87)

• Disk structure & dynamics, SMBH mass (water mega-masers)

• Astrophysical Jet in Active Galactic Nuclei (AGN)

Specifications:

• Two 10-m (in diameter) space antennas

• Three frequency bands (8, 22 & 43 GHz)

• Dual polarization (LCP/RCP)

• Date rate (1.2 Gbps , or 2.4 Gbps)

• Angular resolution: 20 micro-arc-second

• Optimized orbits for a better (u,v) coverage

• Apogee: 60,000 km

• Perigee: 1,200 km

• Inclination: 28.5 deg

• Life time: 3 year

Review Mtg in June 2016

@ CAST (China Academy of Space Technology)

High precision reflector: 10m diameter with a surface accuracy better than 0.4mm (RMS)

Lunar orbit VLBI experiment（LOVE）

• Relay satellite antenna diameter: 4.2m （？）

• Band: X (8-9 GHz), Cooled receiver, bandwidth: 512MHz

• Orbit: 200 km x 8,500 km

• Baseline: ~400,000km, unprecedented longest baseline

• Ground telescope: Big Dishes of Ground VLBI Network，e.g. Tianma 65m、GBT 110m，Effelsberg 100m，SRT 64m, et el.

conception of lunar orbit VLBI experiment

• Space antennas: 2 x 30 m

• Orbit :

– Apogee (60-)90,000 km

– Perigee 2,000 km

– Inclination angle 28.5o

• Frequency Bands:

– 30MHz, 74MHz, 330MHz, 1.7GHz

• Weight: 1.5 Ton/satellite

• Resolution :

– 20mas (30MHz), 8mas (74MHz), 2mas (300MHz),

0.36 mas (1.7GHz)

• Sensitivity：

– BL sensitivity: sub-mJy (int. time =10min)

– image sensitivity: 1 microJy/beam (1h, 1.7GHz)

• Onboard Clocks : H maser or Rb standard

Space VLBI in FAST & SKA era -‘microscope’ probing the Universe from nearby exoplanets to SMBHs in Cosmic Dawn

Low Frequency Twin VLBI Stations in Space

Operation modes

1. Space-ground VLBI

• Unprecedented Super VLBI network consists of

Twin space-based VLBI Stations + ground large telescopes (SKA1, FAST, Arecibo, Effelsberg, GBT, GMRT, QTT......)

• new electromagnetic spectrum window (30 - 300MHz) for space VLBI

2. Space-space VLBI (single baseline)

• Unique space-based VLBI, long integration time, fast response of super-burst of OH masers, auroral radiation from extrasolar systems

3. Space-based single dish

• EoR total power spectrum, pulsar timing array, planets......

Scientific objectives

• EoR and Cosmic Dawn

• Discovery of Jupiter-type exoplanets, Solar flares in nearby stellar systems

• Search for Dual AGN and SMBH binariesin nearby massive galactic centers as remnants of mergers – nano Hz GW sources

• BH (AGN, XRB; Galactic transients) physics: jet launching, collimation, acceleration; GRB, FRB

• Pulsar : accurate astrometry, parallax distance, radiation mechanism; giant pulse

• Planets radio emission

• …

30MHz

74MHz

330MHz

1670MHz

Thank you for your attention!

Welcome collaboration from

all of you!