Science Cases of Korean VLBI Network & Extended KVN Project · Science Cases of Korean VLBI Network...
Transcript of Science Cases of Korean VLBI Network & Extended KVN Project · Science Cases of Korean VLBI Network...
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