The VLBI survey of AGN jets at z > 3 by JVN subarray
Yosuke Furuya
Hiroki Tsuruta, Kotaro Niinuma, Kenta Fujisawa (Yamaguchi university)

INTRODUCTION:
Previous VLBI obs. of high-z AGN jets

INTRODUCTION: Low-z vs. High-z AGN jets
Question: Do AGN jets evolve during cosmological evolution?
M87; z = 0.0042

Low-z AGN jet- Large scale radio jet (pc - kpc scale)- Formation of radio lobe and hotspot

20 kpc1pcHigh-z AGN jet- Large scale jets rarely have been detected- Compact radio structure
J1026+2542; z = 5.3- Some radio sources show special radio spectrum
1 kpc>>> MPS/GPS/HFP (Mega-/Giga-hertz PeakedSpectrum/High Frequency Peaker)◯ Are these differences occurred byobservational bias?
◯ Are these feature effected by environment in
the early Universe?

100 pcFigure 3. The 8.4-GHz VLA A-array image of the quasar J1026+2542
12thEastAsia
VLBI
Workshop@ Ibaraki(experimentAP204,1991
June 19).
The lowest contours
are drawn

INTRODUCTION: Statistical discussion of high-z AGN jet in small sample

Discussion on 30 AGN jets ( z > 4.5 @ 1.7/5 GHz) statistically(Coppejans+16)- FSRQ (Flat Spectrum Radio Quasar) and GPS source are 13, respectively- Radio structures are mostly compact>>> Note that the dynamic-ranges were very low (~ 100)- Observations of the sources have been spent a lot of time (1999 - 2016)
BM: 3.2 x 6.1 mas
σimJ0940+0526: 170 μJy/beam
10 SNR: 108
core
20

01.7 GHz

101.7 GHz

20

Relative Declination (mas)Relative Declination (mas)30

BM: 1.4 x 1.5 mas
σimJ0940+0526: 120 μJy/beam
5SNR: 11630

201001020

Relative Right Ascension (mas)core05 GHz
55 GHzJ0940+0526

J0940+0526
30

30

Others4FSRQ50MPS/GPS
13

513(Coppejans+16)

Relative Right Ascension (mas)FigureFigure1. Naturally
1. Naturally
weightedweighted
1.7 1.7
andand
5 GHz
5 GHz
EVN
EVN
images.
images.
TheTherestoring
restoringbeam
beam(FWHM)(FWHM)is shown
is shown
in pthein pthebottombottomleftleftcorner.
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3 timesthetheimage
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noise,noise,thethepositive
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ForForthethesourcesourceJ1548+3335,
J1548+3335,
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a zoomed-out
versionversiondisplaying
displaying
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both
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in inthethesame
same
image.
image.

We would like to obtain a larger non-biased VLBI
sample in shorter term.
MNRAS
MNRAS
000,000,
1–18
1–18(2016)(2016)

12th East Asia VLBI Workshop @ Ibaraki

The purpose

Do the structure and spectrum of high-z AGN jets
evolve during cosmological timescale?
1. The fringe detection survey for high-z AGN jets
• Make Non-biased VLBI catalog for statistical discussion• Discuss on statistical property about high-z AGN jets
• Pick up the suitable targets which will be detected by VLBI imaging

2. Multi-band VLBI imaging for the detected sources• Discuss on the compact radio structure of high-z AGN jetsstatistically by focusing on the VLBI images and spectrum

12th East Asia VLBI Workshop @ Ibaraki

The plan of our study- From One baseline observation to Largearray
JapaneseVLBI Network
Japanese VLBI NetworkJapanese VLBI Network● ● ●●●EAVN/JVN imaging

Yamaguchi-Ibaraki VLBI survey

Yamaguchi 32m© Yosuke. F

6.7 GHz

Gifu 11m● 6.7 GHz ● 8.4 GHz ● 22 GHz© Yosuke. F● 6.7 GHz ● 8.4 GHz ● 22 GHz© Yosuke. F

8.4 GHz● 22 GHz

Usuda 64m ●●Mizusawa 20m ●●●Japanese VLBI NetworkMizusawa 20m ● 6.7 GHz ● 8.4 GHz ● 22Yamaguchi 32m ●●Gifu 11m ●Usuda 64m ●●Mizusawa 20m ●●●●●●●Japanese
VLBI
NetworkJapanese
VLBI
Network● 6.7Hitachi
GHz ● 32m
8.4 GHz ● 22 GHz ●Japanese VLBI Network●●●Japanese
VLBI
Network●●●●● 6.7 GHz ● 8.4 GHz ● 22 GH
Japanese VLBI Network© Yosuke. F© Yosuke. F

5090100110140130120

15050

8.4 GHz22 GHz43 GHz© Yosuke. F● 6.7 GHz ● 8.4 GHz ● 22 GHz© Yosuke. F

Yamaguchi 32m ●●NANSHAN

40Iriki 20m ●●●Gifu 11m ●40Array90NOBEYAMA

IRIKI

100110120140130

Ishigaki 20m ●●●Freq.

8.4 GHz

Advantage

High baseline sensitivity

PurposeStatistical discussion on nonbias VLBI sample

MethodThe fringe detection survey byone baseline.

Progress

431 targets have been observed

30

Ishigaki 20m ●●●Gifu 11m ●Usuda 64m ●●Kashima 34m ●●●Iriki 20m ●●●Ishigaki 20m ●●●Kashima 34m ●●●Iriki 20m ●●●Ogasawara
20m ●●●
Iriki 20m ●●●20 Ishigaki 20m●●●●150

Ishigaki 20m ●●●Gifu 11m

Ishigaki● 20m ●●●

Gifu 11m ●Kashima 34m ●●●Ishigaki34m20m●●●●●●
Kashima

Takahagi 32m ●●● Usuda 64m●●

Hitachi 32m ●●Takahagi 32m ●●●Hitachi 32m ●●●Yamaguchi 32m ●●© Yosuke. F

Ogasawara 20m ●●●Japanese
VLBI Network
Iriki 20m ●●●Iriki 20m ●●●Mizusawa 20m ●●●Usuda 64m ●●Mizusawa 20m ●●●Japanese VLBI
Network● 6.7 GHz ● 8.4 GHz

Iriki 20m●●●●Mizusawa20m ●Takahagi 32m●●●
Hitachi
32m
Gifu11m● ●●● Mizusawa
Usuda20m64m●●●●●
Usuda64m●●

Yamaguchi
Gifu 11m 32m● ●●Yamaguchi 32m ●●Yamaguchi 32m ●●Gifu 11m ●OGASAWARAISHIGAKI

Mizusawa
20m
Gifu 11m● ●●● Usuda 64m ●●Iriki 20m●●●32mYamaguchi 32m ●●Yamaguchi

MIZUSAWA

Iriki 20m ●●●TIANMA

20ULSANTAMNA

30

Hitachi 32m ●●●UsudaYamaguchi
64m ●●
32m ●●●●YONSEI© Yosuke. F© Yosuke. F

6.7 GHz

Hitachi 32m ●●●Hitachi
32m ●●●●
6.7 GHz ● 8.4 GHz● 22 GHz
Hitachi 32m ●●●© Yosuke. F

Usuda 64m ●●Kashima 34mMizusawa 2●●●

Ogasawara 20m ●●●Kashima 20m34m ●●●●●●Ogasawara
Ogasawara 20m

Takahagi 32m ●Ogasawara20m●●●
Takahagi
32m●●●

Yamaguchi 32m ●●Gifu 11m ●Usuda 64m ●●●●●● Mizusawa 20m ●●●Ishigaki 20m ●●●Kashima 34m ●●●Ogasawara 20m ●●●Takahagi 32m ●●●Ishigaki 20m ●●●Kashima34m●●●
Ogasawara 20m ●●●Takahagi 32m ●●●Iriki 20m●●●
Hitachi 32
Ogasawara 20m
Takahagi
32m

Kashima 34m ●●●●●●22 GHz●●●6.9/8.4 GHz●●●
High baseline sensitivity/High imaging
sensitivity●●●●●●
Iriki 20m

Ishigaki 20mKashima 34m

Hitachi 32m ●●●Ogasawara 20m ●●●Takahagi 32[EAVN]: Resolving compact radio structures at a few pc.
●●●●●●●●●GHz. ●●●[EAVN/JVN]: Discussing on Spectrum
6.9/8.4
to 22
Ishigaki 20m

Kashima 34m

Ogasawara 20m

Takahagi 32m

・Discussing radio structure at high freq.
・Estimating spectral index at VLBI scaleWill be conducted in this November

12th East Asia VLBI Workshop @ Ibaraki

TARGET SELECTION & OBSERVATIONTARGET SELECTION<< Selection criteria >>・The redshift is higher than three (from SDSS DR7/DR10 catalog)
・The estimated flux at 8.4 GHz is higher than 4 mJy (from FIRST)*The spectral index has been assumed flat spectrum.
250
250

Non-VLBIrfc_2017a200
200

NumberNumber150
150

NumberTotal target

588

Detected by VLBI

34

Non-VLBI detection

554* Cross-checked by using VLBI global solution rfc 2017a100
100

We have given the priority toobserving Non-VLBI detected targets.

50
5000
3.0
3.0

3.2

3.4

3.6

3.8

4.2
4.04.0
Redshift
Redshift

4.4

4.6

4.8

5.0
5.0

5.2

12th East Asia VLBI Workshop @ Ibaraki

OBSERVATION: The fringe detection survey by Yamaguchi & Ibaraki

Yamaguchi

Hitachi

Telescope
Frequency
Polarization
BandwidthResolution
Criteria
Correlator

Yamaguchi
Ibaraki
Yamaguchi 32m
Hitachi 32m
8192 - 8704 MHz
RHCP
512 MHz (2 bit/sample)
8.4 mas
SNR > 7
GICO3 (in Yamaguchi univ.)

Observation date
Weather
Tsys [K] Target Sensitivity (6 min)
(UT)
YMG
IBK
YMG IBK[mJy]
1 2018/06/28 03:15-13:15
48
2971
0.86-1.0☁☁2 2019/03/05 22:00-32:00 ☁→☂ ☀→☁ 49
2270
0.46-0.60
3 2019/04/25 09:30-19:30
2278
0.29-0.50☁☀→☂ 564 2019/07/02 03:30-13:30
56
28
72
0.66-0.77☁☁
5 2019/08/01 00:00-10:00
56
2370
0.61-0.72☀☁
6 2019/08/26 22:15-32:15
112 2670
Now correlating☔☀
7 - 9 epoch are going to be observed in this year.
12th East Asia VLBI Workshop @ Ibaraki

RESULT/DISCUSSION:
The fringe detection of our targets

RESULT: 215 targets have been detected (SNR > 7)160
160120120detected
non-detected

140
140

detected
non-detected

1001001201208080Number

NumberNumberNumber100
100
808060606060404040402020202000
3.03

3.2

3.4

3.6

3.84.04

4.2

RedshiftRedshift

4.4

4.6

4.85.05

5.20000

10203040 50
5060708090100
100 110 120 130 140150
150

FLux density [mJy]

Flux density [mJy]• z = 5.303 is the highest redshift in our sample.
• The high detection rates at z > 4 are statistical fluctuation.
(from K-S test)• First detection of 86 sources with Sν < 10 mJy !!
12th East Asia VLBI Workshop @ Ibaraki

DISCUSSION: Redshift distribution of Lv and RL
Luminosity:L⌫ = 4⇡DL⌫ (1 + z)
Radio-loudness: RL ⌘ S8GHz /S<latexit sha1_base64="okvwt1ckypIyECw5J8PuCp2VbS0=">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</latexit>

4770Å

<latexit sha1_base64="qpoMAIB1w9wI2rOkKeF3nQYoPsM=">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</latexit>

100.00 2Luminosity [×1026 W/Hz]S⌫
DL: Luminosity distanceS4770Å: Optical ﬂux density at 4770Å

Discuss the detected target whichluminosity is Lν > 1.37×1026 W/Hz

10Luminosity [x10^26 W/Hz]

1•10.00
101Lν > 1.37×1026 W/Hz

1.00 0In order to discuss targets indifferent redshift, the bias ofdetection limit caused byredshift is removed!

10Detection limit

100.10-1

3.0

4.0

5.0Redshift

6.0z = 5.303

12th East Asia VLBI Workshop @ Ibaraki

DISCUSSION: Redshift distribution of Lv and RL
L⌫ = 4⇡DL⌫ (1 + z) 1 S⌫
D : Luminosity distance
RL⌘
S/S
8GHz
Radio-loudness:
S: Optical ﬂux density at 4770Å

Luminosity:<latexit sha1_base64="okvwt1ckypIyECw5J8PuCp2VbS0=">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</latexit>

L4770Å<latexit sha1_base64="qpoMAIB1w9wI2rOkKeF3nQYoPsM=">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</latexit>

4770Å

100.10-1

3.0inarylim

relog(RL)

P

re

5.00

P

Optical luminosity [x10^26 W/Hz]

re

1.00
100

1.E-0110-1

1.E-0210-2

1.E-0310-3

10
1.E-04
3.0-4

4.0

5.0
Redshift

6.0

lim

10P

Luminosity [×1026 W/Hz]

10.00
101Radio-loudness

inary
1.E+000

lim

10

Optical luminosity [×1026 W/Hz]

100.00 2Luminosity [x10^26 W/Hz]

SDSS luminosity

ina

VLBI luminosity

ryDiscuss the detected target which luminosity is Lν > 1.37×1026 W/Hz

4.0

5.0

6.00.00

3.0Redshift

4.0

5.0

6.0Redshift• SDSS luminosity (g-band) is lower at higher redshift.
• Radio-loudness is higher at higher redshift.

Does this mean “radio activity is higher at higher redshift” ?
12th East Asia VLBI Workshop @ Ibaraki

NEXT OBSERVATION: EAVN/JVN imaging

EAVN/JVN imaging observations
EAVN
50 90

100110120

150 05140130

NANSHAN

4040

MIZUSAWAYONSEI

ULSAN

TAMNA

30IRIKITIANMA
20NOBEYAMA30OGASAWARAISHIGAKI

90100110

Japanese VLBI Network

Network140130120

Japanese VLBI Network

20150● 6.7 GHz ● 8.4 GHz ● 22 GHz© Yosuke. F

Observational information
Resolving pc scale structure @Purpose
high frequency.
Date (UT) 2019/11/21 19:30-11/22 05:30
Freq.
22 GHzStation
KaVA, Tianma, Nanshan
Resolution
0.55 masσI~ 60 μJy/beam (for 2 hr)● 6.7 GHz ● 8.4 GHz ● 22 GHz© Yosuke. F

JVN

Observational information
Obtaining Spectral index
Purpose●●●●●●
between 6.9/8.4 to 22 GHz
●● ●●
● ●●●
●●●●●
●●●● ●●●
●●
●●●
●●
● ●●
●●
●●●
Date(UT)
Now adjusting
●● ●
●
●●
●●●
●●
●●
●●●
Japanese VLBI Network
●●●
●●●
●●●
●●●
Freq.
6.9/8.4 GHz
●●●
●●●
●●●
●●●
●●●●●●●●●●●● ●●●●●●●●●
Station
VERA, Yamaguchi, Hitachi
Japanese●●●VLBI Network
●●●
●●●
●●●
●●
●
●●
●●●
Resolution
4.0/3.2 mas
●●●
●●●
●●●
●●●
●●●
●●●
●●●
●●●
●●●
●●●
●●●
●●●
●●
●
●●
●●●
σI~ 40 μJy/beam (for 2 hr)●●● ●●●●●● ●●●●●● ●●●●●●●●●● 6.7 GHz ● 8.4 GHz● 22 GHz
Usuda 64m ●●© Yosuke. F
Yamaguchi 32m ●●Gifu 11m ●(u,v) coverage

Mizusawa 20m ●●●Japanese VLBI NetworkMizusawa 20m ● 6.7 GHz ● 8.4 GHz ● 22 GHz
Yamaguchi 32m ●●Gifu 11m ●Usuda 64m ●●Mizusawa 20m ●●●●●●●Japanese
VLBI
NetworkJapanese
VLBI
Network● 6.7Hitachi
GHz ● 32m
8.4 GHz ● 22 GHz ● 6.7 GHz ● 8.4 GHz ● 22 GHzJapanese
VLBI Network●●●Japanese
VLBI
Network●● VLBI● Network●● 6.7 GHz ● 8.4 GHz ● 22 GHzJapanese(u,v) coverage© Yosuke. F© Yosuke. F© Yosuke. F© Yosuke. F

6.7 GHz

8.4 GHz22 GHz43 GHz© Yosuke. F● 6.7 GHz ● 8.4 GHz ● 22 GHz© Yosuke. F

Iriki 20m

u 11m ●

Hitachi 32m

UsudaYamaguchi
64m 32m

Mizusawa
20m
Gifu 11m

Iriki 20m
Yamaguchi 32mYamaguchi 32m●●

Yamaguchi 32m

Mizusawa
20m
Takahagi 32m●●●

Hitachi
32m
Gifu11m
Usuda64m

Yamaguchi
Gifu 11m 32m

Yamaguchi 32m
Gifu 11m

Usuda 64m

Gifu 11m
Usuda 64m

Usuda20m64m
Mizusawa

Usuda 64m
Mizusawa 20m
Mizusawa 20m● 6.7 GHz ● 8.4 GHz ● 22 GHz© Yosuke. F

Ishigaki 20m

Kashima 34m

Ogasawara 20m

Usuda 64m

Takahagi 32m●●

Iriki 20m

Iriki 20m●●●●

Ishigaki 20m

Hitachi 32m

Kashima 34m
Iriki 20m

Iriki 20m

Mizusawa 20m

Ogasawara
Iriki 20m 20m

Takahagi 32m

Hitachi 32m

Iriki 20m
Yamaguchi 32m© Yosuke. F

Gifu 11m

Hitachi 32m

Hitachi32m●
6.7 GHz ● 8.4 GHz● 22 GHz
Hitachi 32m

Usuda 64m Kashima 34mMizusawa 20m●●●

Ishigaki 20m●●●●

Ishigaki 20m

Kashima 34m

Hitachi 32m

Ogasawara 20m

Takahagi 32m@ 6.9 GHz

Gifu 11m

Ishigaki● 20m

Ishigaki34m
20m
KashimaKashima 20m
34m
Ogasawara

Ogasawara 20m

Ogasawara
20m
Takahagi
32m

Takahagi 32m

Yamaguchi 32m
Gifu 11m
Usuda 64m
Mizusawa 20m●●●●
Ishigaki 20m
Kashima 34m
Ogasawara
20m
Takahagi 32m
Ishigaki 20m
Kashima34m
Ogasawara 20m
Takahagi 32m
Iriki 20m●●● Takahagi
Hitachi 32m ●●●Ogasawara 20m
32m

34m ●●●●●●●●●

Iriki 20m ●●●Ishigaki 20m ●●●Thank you for your contributions!
Hitachi 32m ●●●Ishigaki 20m ●●●Kashima 34m ●●●Kashima 34m ●●●Ogasawara 20m ●●●Ogasawara 20m ●●●Takahagi 32m ●●●Takahagi 32m ●●●12th East Asia VLBI Workshop @ Ibaraki

SUMMARY

Question:Do AGN jets evolve during cosmological timescale?
Purpose: VLBI large survey for a lot of high-z AGN jets and statistical
discussion for the detected targets about luminosity and Radio-loudness
Result: 215 out of 361 targets (z = 3.0 - 5.3) have been detected by VLBI.
Discussion: Radio-loudness is higher at higher redshift. Opticalluminosity is relatively lower at higher z. It implies “the radio jets evolve
during z = 3.0 - 4.5”.
Next step: EAVN observation for five high-z sources will be conducted inthis November. We plan to investigate the compact radio structure andspectrum of the high-z radio jets.

12th East Asia VLBI Workshop @ Ibaraki