Science Cases of Korean VLBI Network & Extended KVN Project

Taehyun Jung (KASI)

AGN Jet Workshop 2018 2018 Jan 25, Tohoku University, Japan

AGN Jet Workshop 2018 @ Tohoku University Japan (Jan 24-27, 2018)

Korean VLBI Network (KVN)

• 3 Telescopes (D = 21m)

• 22/43/86/129GHz

• 300 - 500 km

• 𝚯 = 1 - 6 mas

• Science Targets

AGN/SF/Evolved Star

+ microquasar

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Yonsei

Tamna

Ulsan

θHBPW ~ 6 mas @ 22 GHz ~ 1 mas @ 129 GHz

AGN Jet Workshop 2018 @ Tohoku University Japan (Jan 24-27, 2018)

Multi-Frequency Receiving System

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• Simultaneous Multi-frequency Observation • @ 22/43/86/129GHz • Dual Pol : LCP & RCP

• (Source) Frequency Phase Transfer • Weak Source Detection • Chromatic Astrometry

• Multi-Frequency Observation • SED • Rotation Measure

AGN Jet Workshop 2018 @ Tohoku University Japan (Jan 24-27, 2018)

Operation & Publications• VLBI ~ 4000h/yr ( + SD ~ 500-1000 h/yr/site)

• KVN Only : 2500h • KaVA (KVN and VERA Array) : 1000h

• EAVN, EVN (22/43GHz), GMVA (86GHz) > 300h

• KVN Key Science Projects : 1000h/yr • KaVA Large Programs : 500h/yr • Global Common Use : 1000h/yr

• KVN : 500h/yr + KaVA : 500h/yr • Total 86 refereed papers since 2013 (SCI: 66)

• 16 SCI papers/yr (half from VLBI observations)

• https://radio.kasi.re.kr/kvn/publication.php

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AGN Jet Workshop 2018 @ Tohoku University Japan (Jan 24-27, 2018)

KVN Key Science Projects

1. Interferometric Monitoring of Gamma-Ray Bright AGN : iMOGABA (Sang-Sung Lee/KASI)

2. Simultaneous Monitoring of KVN 4 Bands towards Evolved Stars (Se-Hyung Cho/KASI)

3. The Plasma Physics of AGN with KVN : PaGAN (Sascha Trippe/SNU)

• KVN Legacy Program: Multi-Frequency AGN Survey with KVN : MASK (KVN Team)

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Interferometric Monitoring of Gamma-Ray Bright AGN : iMOGABA

– Monthly VLBI monitoring of the MOGABA sources (~35) – correlated flux of inner-jet structure after gamma-ray flare – Multi-freq. (22/43/86/129GHz) monitoring

(S-S Lee )

http://radio.kasi.re.kr/sslee/

Interferometric Monitoring of Gamma-Ray Bright AGNs. I. The Results of Single-epoch Multifrequency Observations, S-S Lee+ 2016

Spectra over 22GHz-129GHz can be fitted with a power-law or a curved power-law

J. A. Lee+17 ApJS

Total: 1533 sources874 (57%) observed659 (43%) remained

(until 2017)

Multifrequency AGN Survey with KVN Goal : Constructing Multi-Frequency mm-VLBI Catalog of AGNs

459 sources(Total ~30%) K-band FPT

(KàQ)FPT

(KàW)FPT

(KàD)

Target Freq. 22GHz 43GHz 86GHz 130GHz

Detected 446 401 325 246

Detection Rate 97% 87% 71% 54%

5𝛔 detection limit (mJy)

168 (60)

20 (8)

40 (15)

55(20)

Common sources with ALMA ~300

1Gbps Mode

8Gbps Mode

AGN Jet Workshop 2018 @ Tohoku University Japan (Jan 24-27, 2018)

AGN Torus from Absorption Lines with KVN

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NGC 1052

Surveys with KVNTHE QCAL-1 43 GHz CALIBRATOR SURVEY

(L. Petrove+2012)

• VLBI Source detection at 43GHz : 623 (~78%) • The catalog of correlated flux densities

Korean VLBI Network Calibrator Survey: Source Catalog of KVN Single-dish Flux Density Measurement in the K and Q Bands (J.A. Lee+2017)

• SD Source detection: 1533@K, 533@Q • The catalog of flux densities & SI

SFPR and Astrometry with KVN

• Demonstration of high-precision astrometry up to 130GHz

KVN SFPR demonstration using Polar Cap samples (Rioja+ 2015)

Verification of Astrometric Performance of KVN with VLBA at 14/7 mm (Rioja+ 2014)

Astrometric Error (0854-213 wrt OJ287) RA/Dec ~ 62/32 µas (KVN) RA/Dec ~39/35 µas (VLBA)

Systematic shifts due to structure blending effects

Coreshift measurement of SgrA* (I-J Cho)

Microquasar Study with KVN• When a jet is produced in a flare ? •  How does the jet evolve ? (e.g. spectral inversion)

(Fender+ 1999)

(J.-S Kim)

IDV with KVN

Detection of mm-wavelength IDV in polarized emission from S5 0716+714 (JW Lee+ 2016)

Simultaneous dual-freq. Radio observation of S5 0716+714: A search for IDV with KVN (JW Lee+ 2017)

A Search for AGN IDV with KVN(T Lee+ 2015)

• “anti-correlated” observation mode at 22/43/86/129GHz

• Light curves a short timescale (< 3min)

• 3C279, 3C111, 3C4554.3,BL Lac

• IDV in polarized emission detected by MF Pol Obs. at 22/43/86 GHz

• Significant variations in the degree of linear polarization22GHz : 2.3 —> 3.3%43GHz : 0.9 —> 2.2%86GHz : 0.4 —> 4.0%

• Search for the existence of IDV at 22/43GHz

• Inter-month variability, no clear IDV

• Monotonic flux increase and decrease

2013/12 AA 560The relationship between radio power at 22 and 43 GHz and BH properties of AGN in elliptical Galaxies, Songyoun Park, et al.

2016/02 AN 337, 82High-frequency radio properties of central AGNs in cluster environments, J. Baek et al.2016/02 AN 337, 130Identifying High Frequency Peakers using the Korean VLBI Network, Y. Jeong et al.

And Some More Studies with KVN

(Park+ 2013) (Baek+ 2016) (Jeong+ 2016)

Extended-KVN Project

This presentation is originally made by Do-Young Byun

Original Plan of KVN in 2002

• 2002 IVS Proceedings (Minh)• 4 in South + 2 in North

• EKVN• KASI long-term plan• Future facility of Korea

Astronomical Society

Th 7th Survey Science Workshop 2018 @ Highone

Extended KVN Project• Why new KVN sites ?

– 15 baselines

– more than 5 times better imaging

– Time Domain Astronomy & Rapid Response Science

• Unique baselines : 50 - 500 km

* longer baselines (> 500km) from international collaborations

• Frequency : 18 - 172 (230)GHz

• 45M USD for 3 sites

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KVN 연세

KVN 울산

KVN 탐라

Imaging PerformanceLimitation of 3-station KVN• Poor UV-coverage• No amplitude self-cal • Low success rates

at high frequencies (86/129GHz)

Proportional to # of baselines• Accuracy of VLBI observables

(delay, rate, amplitude)• Image fidelity / dynamic range• Imaging speed

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# of stations 3 4 5 6

# of baselines 3 6 10 15

# of phase closure 1 2 10 20

# of amp. closure N/A 1 5 15

6 times better dynamic range

before after

Amplitude self-cal using VLBA 6 stations

Pyeonchang

Sokcho

Kwangju

UV simulation for site selection• UV-coverage & beam pattern• baselines ~ 50 - 500 km• high success rates• candidates : Sokcho + Pyeonchang

( + Kwangju )

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Imaging Simulation (KVN vs EKVN6)

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Model Image Cleaned Image (KVN) Cleaned Image (EKVN)

Beam Pattern (KVN) Beam Pattern (EKVN)UV-Coverage

Frequency and Resolution of KVN

New Sites in Korea

International Collaboration

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Frequency and Resolution of EKVN

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1mm ~ 15mm submas ~ tens of mas

Th 7th Survey Science Workshop 2018 @ Highone

Wideband Rx Project • Period : 2017 - 2020 • Upgrade current Rx by replacing narrow band components

– LNA, Feed Horn, Polarizer, tunable LO etc • Instantaneous Bandwidth = 8GHz

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Band Wide (GHz) Trx(K) Installation

K 16-26 < 40 2017 - 18

Q 35-50 < 50 2019 - 20

W 84-116 < 80 2018 - 19

D 125-172 < 60 2020

1mm (230GHz) PossibilityAtmospheric condition in Korea• Transparency > 50% (PWV 7.5mm)

~90 days / year

Upgrade of antenna surface accuracy• Both for main dish and secondary mirror • Ant. Eff. ~ 20% (S. A. 110µm) • Ant. Eff. ~ 40% (S. A. 70µm)

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KVN Pointing accuracy (2 arcsec) + Tracking accuracy (1 arcsec) • Gain loss ~ 10%

Global Collaboration for Multi-Frequency

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VERA 22/43, ATCA 43/86, Yebes 40m 22/43/86, NRO45m 22/43/86Tianma 65m 22/43, Thai 40m 22/43, Millimetron 22/43/86/230EHT telescopes ??

EKVN Science Working Group EKVN Science Group Meeting (led by SS Lee)• KVN / Science Group members• S Trippe, JH Park, Algaba(SNU), A Chung, JH Baek (Yonsei Univ.) • H. Imai, S. Sawada-Satoh (Kagoshima Univ.)• 15+ members, Monthly Meeting, White Papers

Science Cases • AGN BH-Jet & AGN feedback• Mass loss mechanism of evolved star ( M/F maser movie)• Dynamical properties and magnetic field of star forming region (methanol

& water masers)• Absorption lines from AGN Torus

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Site Survey

Site Condition• UV coverage • Weather, Sky line, RFI etc• Infra structure, high-speed network connection

Pyeongchang & SokchoPyeongchang Campus of SNUJamboree camping area at Sokcho

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Sky line of Peongchang Campus

7.5deg7deg 10.2deg 17deg 17deg12.7deg

9.6deg

19.2deg

12.2deg2.3deg

Plan

• 2017 : feasibility study and interval review • 2018 : fund request to government• 2020 : construction start• 2024 : EKVN operation

Summary• 2 or 3 x 21m telescopes in Korea

• High surface accuracy for 230GHz observations

• Global collaboration for M/F

• Rapid Response Science

• Automated Operation, e-VLBI, Pipeline

• Synergy with EAVN (~ beam size at 130/230GHz)

• Collaboration with EHT, ngVLA

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Thank for your attention