As onomy &As ophysics
manusc ip no. ou pu ©ESO 2025
Oc obe 6, 2025
Supplemen a y Ma e ial o “Iden i ying compac symme ic
objec s wi h high-p ecision VLBI and
Gaia
as ome y”
T. An1,2,⋆, Y. Zhang1,2, S. F ey3,4,5, W.A. Baan6,1,7and A. Wang1
1Shanghai As onomical Obse a o y, Key Labo a o y o Radio As onomy, CAS, 80 Nandan Road, Shanghai 200030, China
2S a e Key Labo a o y o Radio As onomy and Technology, A20 Da un Road, Chaoyang Dis ic , Beijing, P. R. China
3Konkoly Obse a o y, HUN-REN Resea ch Cen e o As onomy and Ea h Sciences, Konkoly Thege Miklós ú 15-17, H-1121
Budapes , Hunga y
4CSFK, MTA Cen e o Excellence, Konkoly Thege Miklós ú 15-17, H-1121 Budapes , Hunga y
5Ins i u e o Physics and As onomy, ELTE Eö ös Lo ánd Uni e si y, Pázmány Pé e sé ány 1/A, H-1117 Budapes , Hunga y
6Xinjiang As onomical Obse a o y, CAS, 150 Science-1 S ee , Ü ümqi, Xinjiang 830011, P.R. China
7Ne he lands Ins i u e o Radio As onomy, ASTRON, Oude Hooge eensedijk 4, 7991PD Dwingeloo, The Ne he lands
Recei ed 2025; accep ed 2025
ABSTRACT
This Supplemen a y Ma e ial p o ides he ex ended da a ables, figu es, and me hodological de ails suppo ing he analysis p esen ed
in he main pape . I includes he comple e CSO candida e sample, pa ame e lis s and addi ional diagnos ic plo s.
Key wo ds. galaxies: ac i e — galaxies: nuclei — galaxies: je s — quasa s: gene al — adio con inuum: galaxies — as ome y
1. Addi ional ables and figu es
This sec ion compiles he ma e ials suppo ing ou CSO classi-
fica ions. Table 1lis s he ull candida e ca alog (coo dina es,
edshi s, op ical IDs, classifica ions). Table 2 epo s he as-
ome y (angula scales, Gaia- adio offse s, and Gaia quali y
me ics) used in ou me hod. Tables 3–8gi e VLBI imaging,
model-fi ing, and spec al-analysis pa ame e s. Figu e 1shows
he edshi dis ibu ion o he sample. Figu es 2–4show mul i-
equency VLBI maps, spec al-index images, and Gaia o e -
lays ha sepa a e genuine CSOs, whe e he op ical nucleus lies
be ween symme ic lobes, om co e-je sou ces, whe e i si s a
one end. Figu e 5displays he ligh cu es o confi med CSOs.
Figu e 6shows componen p ope mo ions o each CSO.
2.
Gaia
+VLBI c oss-ma ch
We compiled Gaia as ome ic posi ions o ou sou ces di ec ly
om he Gaia da abase1. Fo VLBI da a, we used he Radio Fun-
damen al Ca alogue (RFC, Pe o & Ko ale 2025)2, which cu -
en ly includes o e 20,000 objec s wi h ypically sub-mas p eci-
sion in absolu e VLBI as ome y, achie ed h ough obse a ions
om a ious as ome y and geodesy p og ams. This p ecision
makes he RFC an in aluable esou ce o aligning he op ical
and adio ex agalac ic e e ence amewo ks (as demons a ed
by Bou da e al. 2008).
In ou analysis, we c oss-ma ched he Gaia DR3 ca alog
(Gaia Collabo a ion e al. 2016,2023) wi h he VLBI sample
om Sec ion 2.2 in he main pape , employing a sea ch adius
o 1′′ o iden i y op ical coun e pa s o he adio sou ces. Ou
o 105 VLBI-iden ified CSO candida es, 40 ha e Gaia coun e -
⋆Co esponding au ho : [email p o ec ed]
1h ps://gea.esac.esa.in /a chi e/
2h p://as ogeo.o g/
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Redshi
0
2
4
6
8
Numbe o Sou ces
Co e-je
CSO candida e
CSO
Fig. 1. Redshi dis ibu ion o he sample, including he confi med
CSO, CSO candida e (CSOc), and co e–je (CJ) sou ces.
pa s (Fig. 1 in he main pape ). The modes ma ch a e (38%)
p o ide impo an physical insigh , sugges ing ha mos CSO
nuclei a e op ically ain o obscu ed, highligh ing he unda-
men al challenge in CSO iden ifica ion and he alue o ou
combined Gaia+VLBI app oach. This finding demons a es why
adio–only iden ifica ion me hods ha e p o en insufficien and
alida es ou mul i–wa eleng h s a egy. Since bo h Gaia and
VLBI ca alogs emain in con inuous upda es, he sample sizes
analyzed in his pape a e sligh ly la ge han in hose used in
p e ious s udies.
The as ome ic p ecision o bo h Gaia and VLBI is c i i-
cal o aligning op ical and adio posi ions. Gaia DR3 p o ides
unp eceden ed as ome ic p ecision wi h ypical unce ain ies
o ∼0.04 mas o b igh sou ces (appa en op ical magni ude
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Table 1. The CSO candida e sample collec ed in his pape .
Sou ce name Righ ascension (h m s), declina ion (◦ ′ ′′)zType Re . Classifica ion
J0003+2129 00:03:19.350009 +21:29:44.50822 0.450 Q 2 CJ
J0005+0524 00:05:20.215504 +05:24:10.80305 1.887 Q 2 CJ
J0048+3157 00:48:47.141485 +31:57:25.08483 0.015 G 2 CSO
J0119+3210 01:19:35.001084 +32:10:50.06103 0.0602 G 2 CSOc
J0650+6001 06:50:31.254327 +60:01:44.55477 0.455 Q 1,2 CSOc
J0741+2706 07:41:25.732847 +27:06:45.39211 0.772 Q 3 CSO
J0753+4231 07:53:03.337437 +42:31:30.76470 3.594 Q 1,3 CJ
J0831+4608 08:31:39.802592 +46:08:00.77140 0.131 G 3 CSOc
J0832+1832 08:32:16.040301 +18:32:12.13265 0.154 G 3 CSO
J0906+4636 09:06:15.539809 +46:36:19.02416 0.0847 G 3 CSOc
J0943+1702 09:43:17.223952 +17:02:18.96252 1.600 Q 3 CSOc
J1110+4817 11:10:36.324124 +48:17:52.44997 0.742 Q 3 CSO
J1111+1955 11:11:20.065601 +19:55:36.00040 0.299 G 1,2,3 CSO
J1148+5924 11:48:50.358181 +59:24:56.38223 0.0108 G 1,3 CSOc
J1148+5254 11:48:56.569098 +52:54:25.32250 1.638 Q 2 CJ
J1158+2450 11:58:25.787561 +24:50:17.96392 0.203 G 3 CSO
J1234+4753 12:34:13.330774 +47:53:51.23687 0.373 Q 3 CSO
J1244+4048 12:44:49.187531 +40:48:06.16239 0.814 Q 1,3 CSO
J1247+6723 12:47:33.329586 +67:23:16.44894 0.107 G 2 CSO
J1254+1856 12:54:33.271499 +18:56:01.90866 0.125 G 3 CSOc
J1256+5652 12:56:14.233979 +56:52:25.23760 0.0417 G 2 CSO
J1309+4047 13:09:41.508928 +40:47:57.23878 2.908 Q 2 CSOc
J1310+3403 13:10:04.433638 +34:03:09.10854 0.960 G 3 CSO
J1311+1417 13:11:07.824225 +14:17:46.64778 1.955 Q 1 CJ
J1326+3154 13:26:16.511702 +31:54:09.52057 0.368 G 2,3 CSO
J1335+4542 13:35:21.962189 +45:42:38.23218 2.451 Q 2 CJ
J1358+4737 13:58:40.666477 +47:37:58.31155 0.230 G 3 CSO
J1407+2827 14:07:00.394417 +28:27:14.69011 0.077 G 2 CSO
J1511+0518 15:11:41.266365 +05:18:09.25931 0.084 G 2 CSO
J1559+5924 15:59:01.701929 +59:24:21.83416 0.060 G 2,3 CSOc
J1602+2418 16:02:13.838513 +24:18:37.79350 1.791 Q 3 CSO
J1616+0459 16:16:37.556823 +04:59:32.73651 3.215 Q 2 CJ
J1755+6236 17:55:48.435228 +62:36:44.12661 0.0276 G 2 CSO
J1815+6127 18:15:36.792244 +61:27:11.64744 0.601 Q 1 CSO
J1816+3457 18:16:23.901115 +34:57:45.74704 0.245 G 1,2 CJ
J1823+7938 18:23:14.108654 +79:38:49.00188 0.224 Q 1,2 CSOc
J1945+7055 19:45:53.519774 +70:55:48.72880 0.101 G 1,2 CSO
J2022+6136 20:22:06.681748 +61:36:58.80472 0.227 G 1,2 CJ
J2245+0324 22:45:28.284742 +03:24:08.86404 1.350 Q 1 CJ
J2355+4950 23:55:09.458159 +49:50:08.33951 0.238 G 1,2 CSO
No es. Column (1): sou ce name. Column (2): Equa o ial coo dina es om As ogeo (Pe o & Ko ale 2025). Column (3): Spec oscopic o
pho ome ic edshi s collec ed om he NASA/IPAC Ex agalac ic Da abase (h ps://ned.ipac.cal ech.edu/) o SIMBAD (h ps://
simbad.u-s asbg. /). Column (4) lis s he op ical iden ifica ion o he sou ce ype om SIMBAD. Q – quasa ; G – galaxy. Column (5) lis s
he e e ences o he sou ces. Column (6) p esen s he classifica ion o he adio mo phology: CSO – confi med CSO wi h Gaia-iden ified AGN
be ween wo adio componen s; CJ – one-sided co e–je wi h Gaia-iden ified AGN a he end o he adio s uc u e; CSO candida e – sou ces wi h
la ge op ical– adio offse emain as CSO candida es. Re e ences: 1 – Peck & Taylo (2000); 2 – An & Baan (2012); 3 – T emblay e al. (2016).
G<14mag) and ∼0.7 mas o ain e sou ces (G=20mag).
The RFC deli e s sub-mas as ome ic accu acy o b igh adio
AGN, wi h ypical unce ain ies anging om ∼0.1 o 1 mas.
When combining Gaia and VLBI posi ions, he final unce ain y
is es ima ed o be less han 1 mas o mos sou ces, much smalle
han he ypical sepa a ion be ween he co e and ho spo s in
CSOs (se e al o ens o mas), p o iding a obus ounda ion o
he Gaia+VLBI me hod.
Table 2p esen s he CSO candida e sample collec ed in his
s udy, de ailing key pa ame e s such as hos galaxy ype, angu-
la scale, and as ome ic offse s be ween VLBI and Gaia posi-
ions. The majo i y o he CSOs and candida es in his sample a e
clus e ed a mode a e edshi s (z<1.0), while co e–je sou ces
show a b oade edshi ange, o en ex ending o highe ed-
shi alues (Fig. 1). This dis ibu ion likely eflec s bo h phys-
ical diffe ences in he popula ions and selec ion effec s, wi h
CSOs lacking he Dopple –boos ed emission ha makes co e–
je sou ces de ec able a highe edshi s.
The c oss-ma ched CSO candida es include a he e ogeneous
mix o quasa s, adio galaxies, and o he AGN ypes (e.g. Sey e
galaxies, BL Lac objec s, o unclassified AGN), wi h quasa s
making up ∼40% o he ma ches. This p e alence o quasa s
eflec s mul iple ac o s: Gaia’s sensi i i y o poin –like op ical
sou ces, he highe in insic luminosi y o quasa s enabling de-
ec ion a g ea e dis ances, and VLBI su ey biases a o ing
sou ces wi h compac , b igh adio componen s (Pe o e al.
A icle numbe , page 2 o 28
T. An , Y. Zhang , S. F ey, W.A. Baan and A. Wang: Iden i ying CSOs wi h Gaia and VLBI
Table 2. P ope ies o he CSO candida e sample collec ed in his pape .
Name Type Angula scale Scale Offse RA Offse DEC AEN AENS G
(mas) (pc) (mas) (mas) (mas) (mag)
CSO
J0048+3157 G 11.70 3.59 10.05±1.98 −40.93±1.30 9.21 418.29 17.95
J0741+2706 G 16.90 125.32 7.05±0.75 −0.04±0.75 0.00 0.00 19.49
J0832+1832 G 7.90 21.15 6.14±2.55 2.30±1.71 7.12 19.90 20.07
J1110+4817 Q 22.30 162.87 −6.71±2.62 −10.33±2.63 3.08 1.28 20.73
J1111+1955 G 17.20 76.45 4.06±14.48 −5.80±9.15 18.47 107.18 21.25
J1158+2450 G 8.70 28.89 2.29±1.61 1.51±1.05 4.38 12.81 19.91
J1234+4753 Q 9.70 49.85 −0.97±0.41 0.90±0.38 0.20 2.24 16.84
J1244+4048 Q 29.20 220.43 −0.82±0.62 −0.61±0.80 0.00 0.00 19.75
J1247+6723 G 8.20 16.09 −12.73±5.52 10.37±3.90 18.62 89.49 20.23
J1256+5652 G 47.10 39.19 1.18±0.45 0.11±0.33 0.06 2.55 13.54
J1310+3403 G 15.50 122.88 3.28±6.98 5.62±6.60 9.59 26.84 21.10
J1326+3154 G 56.60 288.74 23.23±2.66 −25.85±2.36 8.56 10.49 20.94
J1358+4737 G 6.60 24.25 −3.15±2.81 1.69±3.19 10.92 101.41 20.59
J1407+2827 G 7.20 10.45 0.95±0.36 0.40±0.48 0.39 9.98 16.35
J1511+0518 G 5.00 7.89 5.74±0.68 −11.01±0.84 2.07 10.69 18.74
J1602+2418 Q 7.50 63.35 −4.92±0.36 1.98±0.53 0.05 0.04 18.02
J1755+6236 G 46.10 25.08 −6.46±2.00 0.40±1.65 2.72 2.17 20.10
J1815+6127 Q 11.00 73.59 0.17±0.95 −3.46±0.79 0.00 0.00 19.95
J1945+7055 G 32.70 60.84 24.11±6.28 −22.00±6.23 27.65 225.44 20.85
J2355+4950 G 49.80 188.92 −5.34±5.82 9.04±5.42 26.44 113.70 21.13
Co e–Je
J0003+2129 Q 4.20 24.19 5.58±4.24 −2.38±2.88 7.13 5.11 21.02
J0005+0524 Q 2.30 19.36 0.10±0.31 −0.24±0.53 0.00 0.00 16.10
J0753+4231 Q 12.00 86.99 0.80±0.44 2.02±0.47 0.22 0.53 17.90
J1148+5254 Q 7.90 66.92 −1.09±0.43 1.04±0.35 0.10 1.13 16.21
J1311+1417 Q 5.20 43.62 1.40±0.85 4.36±0.64 0.87 0.90 19.81
J1335+4542 Q 2.00 16.20 1.01±0.37 −0.47±0.39 0.00 0.00 17.70
J1616+0459 Q ... ... −0.36±0.55 0.29±0.58 0.00 0.00 19.34
J1816+3457 G 35.90 138.21 −4.72±4.31 1.76±4.50 17.63 22.04 21.16
J2022+6136 G 7.10 25.83 13.18±3.26 12.20±4.54 8.92 13.09 20.68
J2245+0324 Q 10.70 89.96 0.00±0.47 0.21±0.64 0.00 0.00 18.81
CSO candida es
J0119+3210 G ... ... −246.77±12.29 58.43±10.31 36.83 193.96 20.37
J0650+6001 Q 6.80 39.41 −0.18±1.25 −3.06±1.33 1.02 0.32 20.72
J0831+4608 G 4.50 10.50 −6.99±6.10 −7.31±4.13 17.68 301.92 20.38
J0906+4636 G 1.70 2.71 −5.69±1.08 7.85±1.06 4.23 30.38 19.26
J0943+1702 Q 13.60 115.21 −2.07±8.09 7.06±10.00 1.95 0.38 20.88
J1148+5924 G 22.80 5.60 −91.04±10.14 68.36±14.50 33.91 417.58 19.15
J1254+1856 G 3.30 6.90 −11.58±2.19 14.69±1.92 8.64 66.16 19.88
J1309+4047 Q 1.30 10.09 −0.82±1.29 −3.89±1.33 0.14 0.24 18.19
J1559+5924 G 7.80 9.07 25.83±2.40 7.88±2.41 9.98 61.47 19.25
J1823+7938 Q 15.70 56.54 −3.11±1.51 3.60±0.98 3.24 8.21 19.85
No es. Column (1): sou ce name; Column (2): hos galaxy ype. Q – quasa ; G – galaxy; Column (3): angula size o he sou ce om ou images in
mas; Column (4): linea scale o he sou ces in pc; Column (5)–(6): angula dis ance (in mas) be ween he X-band peak and he Gaia posi ion along
RA (∆RAcosδ) and DEC(∆DEC ); Column (7): as ome ic excess noise ac o om Gaia DR3; Column (8): as ome ic excess noise significance
om Gaia DR3; Column (9): mean G-band magni ude om Gaia DR3.
2019). Unde s anding hese selec ion effec s is c ucial when in-
e p e ing ou esul s and hei implica ions o CSO e olu ion.
The as ome ic excess noise (AEN) om Gaia, p esen ed
in Table 2, offe s aluable insigh s in o he hos galaxy p ope -
ies. AEN alues o CSOs a e consis en ly la ge han hose o
co e–je sou ces, while CSO candida es exhibi e en highe AEN
alues han confi med CSOs. This end aligns wi h he obse a-
ional e idence ha CSOs a e p edominan ly hos ed by galaxies,
whe eas co e–je sou ces a e ypically associa ed wi h quasa s,
whose compac , b igh nuclei domina e hei op ical emission.
The highe AEN alues o CSOs likely eflec he ex ended and
complex op ical mo phologies o hei hos galaxies, which can
in oduce addi ional sca e in Gaia’s as ome ic measu emen s.
In con as , he lowe AEN alues o co e–je sou ces co e-
spond o he mo e poin -like op ical appea ance o quasa s, dom-
ina ed by b igh nuclea emission. These a ia ions in AEN p o-
ide a quan i a i e measu e ha complemen s adio-based clas-
sifica ions and offe impo an insigh s in o he di e se op ical
cha ac e is ics o AGN hos s.
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Table 3. Image pa ame e s o 20 confi med CSOs shown in Fig. 2.
Name Epoch F eq. Speak σ θbeam
(GHz) (mJy beam−1) (mJy beam−1) (mas, mas, ◦)
J0048+3157 2018-09-01 8.7 269.3 0.21 (1.0, 2.1, −7.3)
2.3 105.7 0.52 (3.6, 8.2, -7.8)
J0741+2706 2018-11-18 8.7 245.3 0.17 (1.1, 2.3, −9.7)
2.3 732.6 0.55 (3.6, 8.8, −10)
J0832+1832 2017-06-10 8.7 116.7 0.23 (1.1, 2.1, 1.0)
2.3 231.8 0.48 (3.8, 7.7, 0.0)
J1110+4817 2018-02-09 8.7 37.7 0.24 (1.2, 1.7, −21.2)
2.3 175.5 0.56 (4.5, 6.7, −21.1)
J1111+1955 2018-03-26 8.7 68.9 0.30 (1.1, 2.4, −7.7)
2.3 498.8 0.85 (3.7, 9.4, −7.0)
J1158+2450 2017-05-01 8.7 301.5 0.31 (1.0, 1.9, −1.5)
2.3 423.6 0.91 (4.1, 7.5, −3.4)
J1234+4753 2018-06-09 8.7 142.3 0.19 (1.1, 1.5, 1.7)
2.3 208.9 0.46 (4.1, 5.5, −1.2)
J1244+4048 2018-07-01 8.7 86.8 0.53 (1.1, 1.6, 9.3)
2.3 142.9 0.69 (3.8, 6.1, 3.3)
J1247+6723 2017-05-27 8.7 57.8 0.22 (1.3, 1.5, −22.7)
2.3 138.7 0.30 (4.6, 5.4, -20.8)
J1256+5652 2018-12-04 8.7 283.7 0.17 (1.1, 1.3, 13.8)
2.3 148.2 0.37 (4.3, 5.3, 12.4)
J1310+3403 2006-07-17 4.8 46.6 0.25 (1.9, 2.9, −7.3)
J1326+3154 2011-05-15 8.7 77.1 0.52 (1.1, 2.0, 3.4)
2.3 459.2 2.72 (3.8, 7.1, −2.1)
J1358+4737 2017-08-12 8.7 172.3 0.25 (1.1, 1.6, 1.8)
2.3 480.0 0.42 (3.9, 5.7, 0.7)
J1407+2827 2018-08-14 8.7 537.5 2.30 (1.3, 2.7, −23.4)
2.3 1312.3 1.83 (4.4, 11.2, −27.4)
J1511+0518 2017-02-20 8.7 349.5 0.29 (0.9, 2.0, −0.1)
2.3 263.0 0.62 (3.4, 7.7, -3.2)
J1602+2418 2018-04-29 8.7 50.3 0.19 (0.9, 1.9, 0.0)
2.3 214.6 0.54 (3.7, 7.6, −3.1)
J1755+6236 2018-12-20 8.7 26.2 0.23 (1.2, 2.0, 69.2)
2.3 43.3 0.72 (4.6, 11.6, −45.1)
J1815+6127 2017-01-16 8.7 92.0 0.26 (1.4, 1.7, 24.5)
2.3 403.9 0.47 (5.4, 6.3, 21.9)
J1945+7055 2018-12-10 8.7 65.8 0.28 (1.1, 1.5, 25.1)
2.3 338.4 0.86 (3.9, 5.3, 20.2)
J2355+4950 2017-04-25 8.6 259.4 0.91 (1.2, 1.5, 57.3)
2.3 892.3 1.27 (3.7, 4.2, 70.3)
No es. Column (1): sou ce name; Column (2): obse ing epoch; Column (3): equency; Column (4): peak in ensi y; Column (5): ms noise o he
pos -fi image; Column (6): es o ing beam shape (majo axis, mino axis, and posi ion angle o he ellip ical Gaussian beam; he posi ion angle is
measu ed om no h o eas ).
In ypical AGN domina ed by compac adio co es, he im-
age cen e aligns wi h he ac ual sou ce coo dina e. Howe e ,
in CSOs, whe e emission is domina ed by lobes and ho spo s,
sel -calib a ion in VLBI p ocessing can shi he image cen e o
he b igh es componen , which may no be he co e. To econ-
cile Gaia posi ions wi h VLBI images, we implemen ed igo ous
as ome ic co ec ions, le e aging absolu e RFC posi ions de-
i ed om g oup–delay measu emen s a S- and X-band (cen al
equencies a 2.3 and 8.4 GHz) minimally affec ed by sou ce
s uc u e and calib a ion e o s (Po cas 2009). This c i ical s ep
ensu es accu a e egis a ion be ween op ical and adio e e ence
ames, o ming he ounda ion o ou classifica ion me hodol-
ogy.
Addi ionally, we accoun o equency-dependen co e
shi s using mul i- equency VLBI da a whene e a ailable
(Lobano 1998), whe e a obus op ically hin je componen
was used o each sou ce. This co ec ion is essen ial o ac-
cu a e VLBI componen iden ifica ion ac oss diffe en obse -
ing equencies and p e en s po en ial misclassifica ions due o
equency-dependen posi ion shi s.
This Gaia+VLBI me hod p o ides a uniquely powe ul and
p ecise app oach o confi ming genuine CSOs, o e coming he
undamen al limi a ions o adi ional mo phological analyses
ha elied on de ec ing o en in isible adio co es. By defini-
i ely pinpoin ing he AGN posi ion, ou app oach enables ac-
cu a e de e mina ion o adio s uc u e o ien a ion and de ailed
s udy o je kinema ics, significan ly enhancing ou unde s and-
ing o CSO physics and hei e olu iona y pa hways.
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Table 4. Image in o ma ion o he 10 confi med co e–je sou ces shown in Fig. 3.
Name Epoch F eq. Speak σ θbeam
(GHz) (mJy beam−1) (mJy beam−1) (mas, mas, ◦)
J0003+2129 2018-07-01 8.7 123.4 0.23 (1.7, 2.6, −14.2)
2.3 160.3 0.44 (3.6, 8.1, −4.5)
J0005+0524 2018-11-03 8.7 74.2 0.21 (1.0, 2.4, −4.4)
2.3 165.6 0.42 (3.8, 10.1, −7.2)
J0753+4231 2018-06-09 8.7 120.0 0.21 (1.2, 1.7 ,10.7)
2.3 300.1 0.64 (4.0, 6.2, 3.6)
J1148+5254 2017-08-05 8.7 465.9 0.32 (1.2, 1.4, 10.3)
2.3 241.6 0.46 (4.3, 5.4, 10.0)
J1311+1417 2018-12-10 8.7 75.3 0.15 (2.3 ,1.0, −4.4)
2.3 520.8 0.32 (9.9, 3.4, −9.4)
J1335+4542 2017-07-16 8.7 515.6 0.30 (1.0, 1.5, 3.0)
2.3 473.1 0.55 (3.8, 5.8, −0.9)
J1616+0459 2009-05-14 8.6 542.7 0.57 (1.1, 2.3, 3.4)
2.3 592.6 0.61 (4.9, 8.7, 5.0)
J1816+3457 2017-03-23 8.7 52.5 0.57 (1.2, 2.6, 7.5)
2.3 187.8 0.72 (4.5, 9.0, 5.4)
J2022+6136 2015-08-24 7.6 1268.9 0.76 (1.3, 2.7, −53.4)
4.3 1114.0 1.81 (2.3, 4.8, −55.9)
J2245+0324 2018-11-18 8.7 176.9 0.23 (1.1, 2.4, 3.5)
2.3 316.4 0.48 (4.1, 9.3, −1.8)
No es. Column (1): sou ce name; Column (2): obse ing epoch; Column (3): equency; Column (4): peak in ensi y; Column (5): ms noise o he
pos -fi image; Column (6): es o ing beam shape (majo axis, mino axis, and posi ion angle o he ellip ical Gaussian beam; he posi ion angle is
measu ed om no h o eas ).
Table 5. Image in o ma ion o he emaining 10 unclassified sou ces shown in Fig. 4.
Name Epoch F eq. Peak σ θbeam
(GHz) (mJy/b) (mJy/b) (mas, mas, ◦)
J0119+3210 2017-06-10 8.7 61.6 0.97 (2.3, 1.2, −4.4)
2.3 220.1 8.54 (4.2,8.3, −4.5)
J0650+6001 2017-07-16 8.7 573.7 0.52 (1.1, 1.3 , 36.8)
2.3 775.3 0.62 (4.8, 4.2, 33.2)
J0831+4608 2006-05-31 4.8 44.8 0.27 (2.0, 2.6, −12.6)
J0906+4636 2017-07-16 8.7 95.7 0.24 (1.0, 1.5, 11.8)
2.3 70.6 0.48 (4.0,5.9,10.7)
J0943+1702 2017-08-05 8.7 188.3 0.21 (1.0, 2.4, −7.8)
2.3 122.5 0.37 (3.7, 9.1, −9.5)
J1148+5924 2017-08-05 8.7 187.7 0.31 (1.2, 1.4, 13.8)
2.3 115.9 0.71 (4.5,5.4,12.3)
J1254+1856 2006-02-25 8.4 78.3 0.22 (1.1, 2.5, 5.3)
4.8 75.5 0.25 (2.1,3.4,−3.5)
J1309+4047 2022-07-26 7.6 36.8 0.42 (2.6, 0.9, 4.5)
2.3 77.1 0.41 (1.5, 4.4, 1.5)
J1559+5924 2017-05-12 8.7 43.4 0.21 (1.2, 1.4, −66.2)
2.3 113.5 0.43 (4.9,5.5,-45.9)
J1823+7938 2000-12-04 8.6 182.4 0.32 (1.1, 1.6, 46.5)
2.3 185.7 2.62 (4.9, 6.1, 41.3)
No es. Column (1): sou ce name; Column (2): obse ing epoch; Column (3): equency; Column (4): peak in ensi y; Column (5): ms noise o he
pos -fi image; Column (6): es o ing beam shape (majo axis, mino axis, and posi ion angle o he ellip ical Gaussian beam; he posi ion angle is
measu ed om no h o eas ).
3. VLBI da a educ ion and analysis
3.1. Con inuum images
We ob ained a chi e VLBI da a o 40 CSO candida es om he
As ogeo da abase. Mos o hese da a o igina e om as ome -
ic VLBI p ojec s, such as he VLBA Calib a o Su eys (e.g.
Beasley e al. 2002;Fomalon e al. 2003;Pe o e al. 2005,
2006;Ko ale e al. 2007;Pe o e al. 2008;Pe o 2016), and
consis o p e-p ocessed and sel -calib a ed isibili y da a, o en
including simul aneous S-band (2.3 GHz) and X-band (8.4 GHz)
obse a ions. Fo hese p e-calib a ed da ase s, we used s an-
da d hyb id mapping using he so wa e package Di map (Shep-
he d 1997), i e a i ely pe o ming clean decon olu ion and sel -
calib a ion o efine he imaging quali y.
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Table 6. P ope mo ions o he co e–je sample in Fig. 7.
Name Comp. µ ad βapp PA a
(mas y −1) (c) (◦y −1)
J0003+2129 J2 0.055±0.002 1.50±0.04 0.49±0.01
J1 0.058±0.008 1.57±0.23 −0.04 ±0.08
J0005+0524 J1 0.070±0.001 5.55±0.10 −1.36 ±0.12
J1311+1417 J1 0.031±0.004 2.54±0.32 −0.16 ±0.07
J1335+4542 J3 0.025±0.001 2.28±0.05 −0.53 ±0.47
J2 0.022±0.001 2.03±0.05 0.02±0.05
J1 0.050±0.001 4.53±0.11 0.02±0.02
J2022+6136 J2-J1 0.083±0.001 1.20±0.01 0.02±0.03
J2245+0324 J1 0.010±0.001 0.67±0.05 −0.14 ±0.01
No es. Column (1): sou ce name; Column (2): componen ID; Column (3): adial p ope mo ion o he componen wi h espec o he co e; Column
(4): posi ion angle change o he componen wi h espec o he co e, measu ed om no h o eas .
We implemen ed a igo ous quali y con ol p ocess, inspec -
ing each da ase and selec ing epochs wi h op imal signal- o-
noise a io ( ypically >10 o he weakes sou ce compoen s
o in e es ) and (u, )-co e age a X-band o ensu e he high-
es possible fideli y in ou esul ing images. When X-band da a
we e una ailable, we subs i u ed C-band (4.8 GHz) obse a-
ions, main aining consis en esolu ion ac oss he sample. Con-
inuum images we e p oduced o each selec ed epoch, wi h
Gaia DR3 posi ions o e laid o compa e he op ical cen oid
wi h he VLBI adio s uc u e, ocusing on he co e iden ifica-
ion (Figs. 2,3, and 4). This app oach allows us o di ec ly assess
he alignmen be ween he op ical and adio emission, aiding in
CSO classifica ion and unde s anding sou ce mo phology.
3.2. Spec al index map
Accu a e spec al index measu emen s equi e quasi-
simul aneous mul i- equency obse a ions. The simul aneous
dual– equency (2.3/8.4 GHz) VLBI da a om he as ome y
p og am p o ide an ideal oppo uni y o cons uc eliable
spec al index maps la gely ee om a iabili y effec s, offe ing
c i ical diagnos ic in o ma ion abou emission mechanisms in
diffe en egions o he sou ce.
We fi s p oduced FITS images om he calib a ed isibili y
da a o bo h he S- and X-band ( ypically 2.3 GHz and 8.4
GHz, espec i ely), ensu ing hey had he same pixel size and
map dimensions. We ha e used a common isibili y ange in
wa eleng h uni s a bo h equencies o ensu e consis ency in he
spec al index calcula ion. S anda d imaging and sel -calib a ion
p ocedu es we e pe o med using he AIPS ask IMAGR. I S-
band da a we e una ailable, C-band images ( ypically 4.8 GHz
o 5 GHz) we e used as a subs i u e.
To ensu e ha he spec al index calcula ion is sensi i e o
emission on simila angula scales and a oids a ificial spec al
ea u es due o esolu ion diffe ences, we ma ched he angula
esolu ion. Specifically, we con ol ed he highe - esolu ion X-
band images wi h a Gaussian beam ma ching ha o he lowe -
equency images using he AIPS ask CONVL and Di map ask
es o e.
In o de o p ecisely align mul i– equency images, a c i i-
cal equi emen o meaning ul spec al analysis, we used op-
ically hin, s eep–spec um componen s ( ypically ho spo s o
lobes) as e e ence poin s whe e a ailable and clea ly iden ifi-
able in bo h bands. These ea u es a e gene ally less affec ed by
equency-dependen posi ion shi s and main ain consis en po-
si ions. Only sou ces wi h eliable componen iden ifica ion al-
lowing o unambiguous alignmen we e used o spec al index
mapping. The images we e shi ed based on calcula ed offse s
using AIPS ask OGEOM o gua an ee ha he same physical
componen s we e supe imposed ac oss equencies.
The spec al index (α, defined ia Sν∝ν−α) maps we e hen
gene a ed om he aligned, esolu ion-ma ched images, using
he AIPS ask COMB wi h he OPCODE=’SPIX’. To ensu e e-
liabili y, pixels in he inpu o al in ensi y maps alling below a
signal- o-noise a io (SNR) h eshold, ypically se a 5 imes im-
age ms noise, we e usually blanked be o e o du ing he spec al
index calcula ion, he eby excluding low-SNR pixels om he fi-
nal spec al index map.
The esul ing spec al index dis ibu ions o each CSO and
co e–je sou ce a e shown in Figs. 2and 3. Spec al index maps
help dis inguish be ween co e and je componen s: co es yp-
ically exhibi fla o in e ed spec a (α≲0.5), while je s
and ho spo s ha e s eep spec a (α≳0.5) (Kelle mann e al.
1994). This addi ional spec al in o ma ion enhances sou ce
classifica ion and helps elucida e hei physical p ope ies. Fo
J1310+3403, only 4.8-GHz da a we e a ailable om he a chi e,
so a spec al index map could no be cons uc ed. Fo he CSOc
sou ces, we made spec al index maps, excep o J0119+3210,
J0906+4636 and J0831+4608. The fi s wo sou ces lack eliable
op ically hin componen s o alignmen s and he las one only
has 4.8-GHz da a om he a chi e (see Fig. 4).
3.3. P ope mo ion analysis
P ope mo ion measu emen s help cons ain CSO expansion
speeds, which a e c ucial o es ima ing kinema ic ages and un-
de s anding e olu iona y s ages. In co e–je sou ces, je speeds
p o ide insigh s in o je dynamics and ela i is ic beaming e -
ec s. We analyzed he kinema ics o CSOs and co e–je sou ces
using mul i-epoch VLBI da a. In CSOs, we measu ed he sepa-
a ion speed be ween e minal ho spo s o ho spo –co e, while in
co e–je sou ces, we acked je componen s ela i e o he co e.
We used he model i ask in Di map, employing ci cula
Gaussian componen s o ep esen emission ea u es. This ap-
p oach p o ided a simple and consis en model o he com-
pac s uc u es obse ed. Gi en he a ying da a quali y ac oss
epochs, we ocused on fi ing he b igh es componen s ha
could be eliably iden ified ac oss all epochs.
I wo componen s we e oo close o i he decon ol ed
size was significan ly smalle han he es o ing beam, we e-
placed he Gaussian wi h a poin -sou ce model. Ou p ima y
conce n was de e mining componen posi ions accu a ely a he
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T. An , Y. Zhang , S. F ey, W.A. Baan and A. Wang: Iden i ying CSOs wi h Gaia and VLBI
han modeling exac shapes o sizes; hus, using ci cula Gaus-
sians o poin sou ces did no significan ly affec he p ope mo-
ion esul s.
Table 7and 8lis he model fi ing pa ame e s, including in-
eg a ed flux densi y (S o ), adial sepa a ion (R) wi h espec o
he Gaia posi ion and he posi ion angle (PA) measu ed om
no h o eas , componen size θFWHM ( ull wid h a hal maxi-
mum o he fi ed Gaussian), and b igh ness empe a u e (Tb).
The e o es ima es a e desc ibed in Appendix 4.
O hese iden ified CSO and co e–je sou ces, 21 ha e mul i-
ple X-band VLBI epochs, allowing measu emen o ho spo sep-
a a ion speeds o je p ope mo ions o e ime baselines anging
om a ew yea s o 25 yea s ( he ea lies da a a e om 1994).
Fo sou ces wi h mo e han wo epochs a ailable, we de i ed
p ope mo ions using linea eg ession o componen posi ions
o e ime. Fo hose wi h only wo epochs, we calcula ed appa -
en speeds based on posi ional changes be ween hese epochs.
Two sou ces (e.g. J1755+6236/NGC 6251, J2355+4950)
we e excluded om p ope mo ion analysis due o insufficien
ime baselines, poo da a quali y, o ambiguous componen iden-
ifica ion. In some CSOs, we also measu ed he p ope mo ions
o inne je componen s in addi ion o e minal ho spo s o gain
u he insigh s in o kinema ics and dynamical e olu ion.
3.4. E o analysis and iden ifica ion eliabili y
To ensu e he obus ness o ou CSO iden ifica ions, we con-
duc ed a comp ehensi e e o analysis inco po a ing all po en ial
sou ces o unce ain y in bo h Gaia and VLBI measu emen s.
Gaia posi ion e o s ange om 0.04 o 0.7 mas. Ch oma ic e -
o s a ising om he wa eleng h-dependen poin -sp ead unc-
ion o he Gaia op ics can shi posi ions, pa icula ly o AGN
wi h significan ul a iole o in a ed emission (Lindeg en e al.
2018). P ope mo ion and pa allax unce ain ies we e accoun ed
o , hough hey a e gene ally negligible o dis an ex agalac ic
sou ces (Fab icius e al. 2021).
Fo VLBI measu emen s, we accoun ed o he mal noise,
oposphe ic delay (in oducing posi ion e o s o ∼0.1–1 mas),
and ionosphe ic effec s, which a e mo e p onounced a lowe
equencies (So e s e al. 1998). Sou ce s uc u e effec s we e
c i ically assessed, as ex ended o complex adio mo phologies
can cause significan as ome ic shi s i no p ope ly mod-
eled (Cha lo 1990;Po cas 2009). This is especially ele an o
CSOs, whe e co e emission is o en weak o obscu ed, and dom-
inan emission a ises om he lobes o ho spo s.
Gaia and VLBI posi ion e o s we e combined in quad a-
u e, p o iding a conse a i e es ima e o he o al unce ain y in
op ical– adio alignmen . We used a Mon e Ca lo app oach, gen-
e a ing 1000 ealiza ions o Gaia and VLBI posi ions o each
sou ce, based on Gaussian e o dis ibu ions. Fo each ealiza-
ion, we calcula ed he offse be ween Gaia and VLBI posi ions,
de e mining he likelihood ha he op ical posi ion ma ches a
pa icula adio componen .
This comp ehensi e e o analysis enhances he c edibili y
o ou esul s and allows o nuanced in e p e a ion o bo de line
cases, con ibu ing o efined CSO iden ifica ion me hodologies.
By quan i ying he eliabili y o each iden ifica ion, we p o ide
a solid ounda ion o subsequen analyses o CSO p ope ies,
such as kinema ic ages and expansion speeds, and demons a e
he powe o combining op ical and adio as ome y o u u e
s udies.
4. E o analysis o he VLBI componen s
The e o s o he fi ed Gaussian componen s a e mainly in o-
duced by Fomalon (1999) and modified o he s ong side lobes
o VLBI obse a ions:
SNR =Speak
σpeak
(1)
σpeak =σ(2)
σin =σ×√1+Sin
Speak
(3)
σpos =θbeam
2 SNR (4)
σsize =θbeam
2 SNR (5)
σPA =a c an (σpos
R),(6)
whe e SNR is he signal- o-noise a io, σ he ms noise o he im-
age, σpeak he pos -fi oo -mean-squa e e o o he fi ed com-
ponen , σin he unce ain y o he in eg a ed flux densi y, σpos
and σsize he unce ain y o he fi ed componen posi ion and
size, σPA he unce ain y o he fi ed componen posi ion an-
gle, Speak he peak in ensi y o he componen , Sin he o al in-
eg a ed flux densi y, θbeam is he ull wid h a hal maximum
(FWHM) size o he es o ing beam, √bmaj ·bmin, and R he a-
dial dis ance o he componen wi h espec o he co e.
Addi ional calib a ion e o s depend on he accu acy o he
isibili y ampli ude calib a ion. Acco ding o he VLBA obse -
a ional s a us epo 3, he ac ional calib a ion e o o flux
densi y is abou 5% a 1.5–15 GHz equency bands. We hus
apply 5% as he calib a ion e o o he peak in ensi ies and o-
al flux densi ies.
5. Co e b igh ness empe a u e and adio
luminosi y
We compu ed wo undamen al physical pa ame e s o he
CSOs: he co e (o b igh ho spo ) b igh ness empe a u e and
he adio luminosi y. The b igh ness empe a u e, TB, was calcu-
la ed ollowing Kelle mann & Owen (1988):
TB=1.22 ×1012 K(S o
Jy )(θFWHM
mas )−2(ν
GHz)−2(1 +z),(7)
whe e νis he obse ing equency, z he edshi , θFWHM he
angula size o he componen , and S o i s in eg a ed flux den-
si y.
The monoch oma ic adio powe a 1.4 GHz was de i ed as
P1.4 GHz =4πD2
LS1.4 GHz(1 +z)−(α+1),(8)
whe e DLis he luminosi y dis ance, S1.4 GHz he obse ed
1.4 GHz flux densi y, and α he spec al index. Fo GHz-peaked
sou ces wi h u no e abo e 1.4 GHz (op ically hick a his e-
quency), we used flux densi ies a highe equencies and ex ap-
ola ed o 1.4 GHz wi h he op ically hin spec al index om ou
mul i- equency da a. This yields a mo e eliable in insic powe
es ima e, less affec ed by abso p ion a 1.4 GHz.
3h ps://science.n ao.edu/ acili ies/ lba/docs/
manuals/oss
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6. The eliabili y o
Gaia
posi ions co ela ing wi h
VLBI obse a ions
As discussed in Sec ion 2 o he main pape , Gaia as ome-
y can be impac ed by as ome ic excess noise (AEN) and i s
significance (AENS), which quan i y depa u es om he fi e-
pa ame e solu ion and may a ise om ex ended hos s o sub-
kpc op ical je s (see also Lindeg en e al. 2012; DR3 docs4).
These me ics ha e been used, oge he wi h Gmagni ude, o se-
lec dual-AGN candida es (e.g. Chen e al. 2023;Schwa zman
e al. 2024); o example, Schwa zman e al. (2024) adop ed
AENS >5, G<20, and z>0.5 o mi iga e spu ious ji e om
la ge nea by galaxies.
Table 2lis s, o each sou ce, he VLBI angula scale,
AEN/AENS, and G. In ou sample, confi med CSOs and CSO
candida es clus e a ele a ed AEN/AENS (ji e ing), consis en
wi h ex ended op ical hos s, whe eas confi med sou ces wi h
z>0.5 gene ally ha e clean Gaia de ec ions. These ends
align wi h he eliabili y ca ea s summa ised in Sec ion 2.3 o
he main pape and in o m ou conse a i e use o Gaia–VLBI
offse s in classifica ion.
7. Co ela ion analysis o he je pa ame e s
To quan i a i ely in es iga e he ela ionships in Figu e 2 o he
main pape be ween key physical pa ame e s in ou CSO sample,
we pe o med comp ehensi e co ela ion analyses using h ee
complemen a y s a is ical me hods: Pea son (pa ame ic), Spea -
man (non-pa ame ic ank), and Kendall (non-pa ame ic ank)
co ela ion coefficien s. These diffe en app oaches allow us o
iden i y bo h linea and non-linea ela ionships while assessing
obus ness agains ou lie s and non-no mal dis ibu ions. We p i-
ma ily use he esul s o he Pea son me hod o e alua ion, wi h
Spea man and Kendall me hods as supplemen a y checks.
Table 9summa izes he co ela ion coefficien s and p- alues
o he key pa ame e pai s ac oss he h ee s a is ical me hods.
S a is ical significance was assessed using p- alues, wi h p<
0.05 conside ed s a is ically significan .
Radio powe shows a mode a e and highly significan co -
ela ion wi h bo h p ojec ed size ( =0.483, p=0.004) and
ho spo eloci y ( =0.481, p=0.004), implying ha mo e
powe ul sou ces a e gene ally la ge and hos as e –mo ing
ho spo s (Fig. 2-aand b, he main pape ). P ojec ed size addi-
ionally co ela es wi h ho spo eloci y (Fig. 2-co he main
pape ) and wi h spec al index (Fig. 2-ho he main pape ), in-
dica ing ha la ge CSOs can main ain ela i ely high ad ance
speeds while exhibi ing s eepe synch o on spec a.
A significan nega i e co ela ion be ween ho spo eloci y
and kinema ic age ( =−0.44, p=0.009) e eals sys ema ic
ho spo decele a ion as a sou ce ages (Fig. 2-eo he main pa-
pe ), likely due o inc easing am p essu e as ho spo s encoun e
dense ambien medium a la ge adii, combined wi h g owing
ins abili ies a he wo king su ace and possible en ainmen o
ambien ma e ial.
The size–age link (Fig. 2- o he main pape ) shows only
ma ginal significance (p≈0.054). This weak co ela ion sug-
ges s ha while olde sou ces end o be somewha la ge , he
ela ionship is complica ed by a ying expansion a es, en i-
onmen al in e ac ions, and possible episodic je ac i i y. Some
sou ces may expe ience pe iods o apid expansion ollowed by
4h ps://gea.esac.esa.in /a chi e/documen a ion/GDR3/
pd /GaiaDR3_documen a ion_1.2.pd
s agna ion, while o he s main ain s eady bu slow g ow h, lead-
ing o conside able sca e in he size-age plo .
The posi i e co ela ion be ween p ojec ed size and spec al
index ( =0.39, p=0.0241, Fig. 2-ho he main pape ) e-
flec s synch o on aging p ocesses, whe e la ge sou ces con ain
olde elec on popula ions ha ha e expe ienced mo e adia i e
cooling and adiaba ic expansion, esul ing in s eepe spec a.
These co ela ion analyses highligh he in e play be ween
je powe , physical size, ho spo dynamics, and e olu iona y p o-
cesses in CSOs, p o iding insigh s in o hei g ow h and in e ac-
ion wi h he su ounding medium.
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Table 7. Model-fi ing pa ame e s o VLBI componen s o CSOs.
.
Name Epoch Label Sin RPA θFWHM Tb
(mJy) (mas) (◦) (mas) (K)
(1) (2) (3) (4) (5) (6) (7) (8)
J0832+1832 1996/01/02 E 168.6±8.5 / / 0.13±0.01 (2.0±0.2)×1011
W 86.6±7.7 7.37±0.16 46.6±0.4 2.37±0.11 (3.1±0.3)×108
2012/02/20 E 140.1±7.8 / / 0.46±0.03 (1.3±0.2)×1010
W 76.6±12.0 7.31±0.24 45.1±1.0 2.00±0.25 (3.9±0.9)×108
2014/06/09 E 78.7±4.3 / / 0.33±0.03 (1.3±0.2)×1010
W 36.3±3.7 7.40±0.21 44.9±0.6 2.07±0.16 (1.6±0.2)×108
2017/06/10 E 133.4±10.1 / / 0.80±0.07 (3.9±0.6)×109
W 92.5±14.5 7.50±0.18 45.8±0.9 2.24±0.23 (3.5±0.7)×108
2018/07/31 E 71.4±6.5 / / 0.71±0.09 (2.7±0.5)×109
W 33.1±8.0 7.87±0.19 45.9±1.3 1.93±0.35 (1.7±0.6)×108
J1110+4817 2007/08/01 NE1 81.1±4.2 / / ≤0.32 ≥2.3×1010
NE2 14.5±1.7 6.03±0.33 −161.8±1.3 1.15±0.28 (3.1±1.1)×108
SW 8.3±1.5 22.38±0.34 −145.8±0.5 ≤1.18 ≥1.7×108
2014/08/09 NE1 44.0±2.3 / / 0.36±0.02 (9.7±0.9)×109
NE2 8.8±0.9 5.93±0.17 −158.2±0.6 1.45±0.12 (1.2±0.2)×108
SW 10.5±1.0 22.68±0.16 −143.8±0.2 1.85±0.12 (8.7±1.2)×107
2017/02/24 NE1 47.6±2.9 / / 0.39±0.04 (8.6±1.2)×109
NE2 8.3±0.8 5.85±0.15 −161.8±0.4 0.58±0.09 (6.9±1.6)×108
SW 6.6±0.5 22.24±0.15 −144.6±0.1 1.25±0.08 (1.2±0.1)×108
2018/02/09 NE1 39.8±2.9 / / 0.68±0.07 (2.4±0.4)×109
NE2 9.0±0.8 5.78±0.17 −162.2±0.5 1.21±0.10 (1.8±0.3)×108
SW 9.1±0.7 22.19±0.16 −145.2±0.1 0.72±0.07 (4.9±0.8)×108
J1111+1955 2015/03/17 W 69.5±5.1 / / ≤0.38 ≥1.0×1010
E 15.3±2.8 16.30±0.21 118.0±0.4 ≤0.68 ≥6.9×108
2017/01/16 W 99.5±13.2 / / 1.86±0.20 (6.0±1.2)×108
E 42.5±2.9 16.85±0.14 117.6±0.1 0.65±0.06 (2.1±0.3)×109
2018/03/26 W 124.0±21.5 / / 2.06±0.27 (6.1±1.5)×108
E 52.9±5.6 17.19±0.17 117.9±0.2 0.84±0.13 (1.6±0.4)×109
No es. We ha e a oided he e he a chi al VLBI da a o some epochs o bad quali y in e ms o signal- o-noise a io and as ome ic posi ions.
Also, he ela i e posi ions o he componen s in J0832+1832 and J1358+4737 a e gi en wi h espec o hei b igh es componen posi ion. The
componen s a e ma ked in o de o ei he Eas o Wes o No h o Sou h di ec ion.
Re e ences
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A icle numbe , page 9 o 28
A&A p oo s:
manusc ip no. ou pu
mJy
/
b
mJy
/
b
20020
Rela i e RA (mas)
20
0
20
Rela i e DEC (mas)
2.3-8.7 GHz
2018-06-09
J1234+4753 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
402002040
Rela i e RA (mas)
40
20
0
20
40
Rela i e DEC (mas)
2.3-8.7 GHz
2018-07-01
J1244+4048 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
200204060
Rela i e RA (mas)
60
40
20
0
20
Rela i e DEC (mas)
2.3-8.7 GHz
2018-08-10
J1326+3154 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
201001020
Rela i e RA (mas)
20
10
0
10
20
Rela i e DEC (mas)
2.3-8.7 GHz
2018-09-02
J1358+4737 0.5
0.0
0.5
1.0
1.5
Fig. 2. Con inued.
A icle numbe , page 16 o 28
T. An , Y. Zhang , S. F ey, W.A. Baan and A. Wang: Iden i ying CSOs wi h Gaia and VLBI
mJy
/
b
mJy
/
b
2010010
Rela i e RA (mas)
20
10
0
10
20
Rela i e DEC (mas)
2.3-8.7 GHz
2018-04-29
J1602+2418 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
20020
Rela i e RA (mas)
20
0
20
Rela i e DEC (mas)
2.3-8.7 GHz
2017-01-16
J1815+6127 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
402002040
Rela i e RA (mas)
60
40
20
0
20
40
Rela i e DEC (mas)
2.3-8.6 GHz
2017-04-25
J2355+4950 0.5
0.0
0.5
1.0
1.5
Fig. 2. Con inued.
A icle numbe , page 17 o 28
A&A p oo s:
manusc ip no. ou pu
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
402002040
Rela i e RA (mas)
40
20
0
20
40
Rela i e DEC (mas)
2.3-8.7 GHz
2017-05-27
J1247+6723 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
402002040
Rela i e RA (mas)
40
20
0
20
Rela i e DEC (mas)
2.3-8.7 GHz
2018-12-10
J1945+7055 0.5
0.0
0.5
1.0
1.5
Fig. 2. Con inued.
A icle numbe , page 18 o 28
T. An , Y. Zhang , S. F ey, W.A. Baan and A. Wang: Iden i ying CSOs wi h Gaia and VLBI
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
Fig. 3. VLBI images o confi med co e–je sou ces o e laid wi h hei Gaia posi ions loca ed a he p esumable je bases. The ed c osses ma k
he Gaia posi ions and he o ange c osses o e laid wi h caps ep esen he posi ional e o s o he Gaia posi ions wi h espec o hei VLBI peaks.
The spec al index maps a e also p esen ed. The Gaia posi ion is associa ed wi h he b igh es componen a he end o he je , which deno es he
AGN loca ion.
A icle numbe , page 19 o 28
A&A p oo s:
manusc ip no. ou pu
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
Fig. 3. Con inued.
A icle numbe , page 20 o 28
T. An , Y. Zhang , S. F ey, W.A. Baan and A. Wang: Iden i ying CSOs wi h Gaia and VLBI
mJy
/
b
mJy
/
b
C
S
N
mJy
/
b
mJy
/
b
402002040
Rela i e RA (mas)
40
20
0
20
40
Rela i e DEC (mas)
2.3-8.7 GHz
2017-08-05
J0943+1702 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
Fig. 4. VLBI images o he 10 emaining candida e CSOs showing a la ge offse be ween he peaks o he op ical and adio emissions. Howe e ,
hei VLBI images s ill display he cha ac e is ic iple mo phology ypical o CSOs. Fo J0119+3210 and J0906+4636, no op ically hin com-
ponen s can be ound o link he dual-band images, he e o e no spec al index maps can be made. Fo J0831+4608, only one C-band (4.8 GHz)
image is a ailable.
A icle numbe , page 21 o 28
A&A p oo s:
manusc ip no. ou pu
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
20020
Rela i e RA (mas)
20
0
20
Rela i e DEC (mas)
2.3-8.6 GHz
2000-12-04
J1823+7938 0.5
0.0
0.5
1.0
1.5
mJy
/
b
mJy
/
b
mJy
/
b
mJy
/
b
Fig. 4. Con inued.
A icle numbe , page 22 o 28
T. An , Y. Zhang , S. F ey, W.A. Baan and A. Wang: Iden i ying CSOs wi h Gaia and VLBI
1995 1998 2001 2004 2007 2010 2013 2016 2019
Epoch (yea )
200
300
400
500
600
700
800
Flux Densi y (mJy)
J0832+1832
To al_X
To al_S
2008 2010 2012 2014 2016 2018
Epoch (yea )
50
100
150
200
250
300
350
400
450
Flux Densi y (mJy)
J1110+4817
To al_X
To al_S
2016 2017 2018
Epoch (yea )
400
600
800
1000
1200
Flux Densi y (mJy)
J1111+1955
To al_X
To al_S
1998 2001 2004 2007 2010 2013 2016
Epoch (yea )
200
400
600
800
1000
Flux Densi y (mJy)
J1158+2450
To al_X
To al_S
1998 2001 2004 2007 2010 2013 2016 2019
Epoch (yea )
200
250
300
350
400
Flux Densi y (mJy)
J1234+4753
To al_X
To al_S
2012 2013 2014 2015 2016 2017 2018
Epoch (yea )
200
400
600
800
Flux Densi y (mJy)
J1244+4048
To al_X
To al_S
2008 2010 2012 2014 2016 2018
Epoch (yea )
100
150
200
250
Flux Densi y (mJy)
J1247+6723
To al_X
To al_S
1995 1998 2001 2004 2007 2010 2013 2016 2019
Epoch (yea )
150
200
250
300
350
400
Flux Densi y (mJy)
J1256+5652
To al_X
To al_S
2006 2008 2010 2012 2014 2016 2018
Epoch (yea )
200
300
400
500
600
700
Flux Densi y (mJy)
J1358+4737
To al_X
To al_S
19961998 20002002 20042006 20082010 20122014
Epoch (yea )
1000
1200
1400
1600
1800
Flux Densi y (mJy)
J1407+2827
To al_X
To al_S
2002 2004 2006 2008 2010 2012 2014 2016 2018
Epoch (yea )
300
400
500
600
700
Flux Densi y (mJy)
J1511+0518
To al_X
To al_S
2008 2010 2012 2014 2016 2018
Epoch (yea )
100
150
200
250
300
Flux Densi y (mJy)
J1602+2418
To al_X
To al_S
2015 2016 2017 2018
Epoch (yea )
200
300
400
500
600
700
800
900
1000
Flux Densi y (mJy)
J1815+6127
To al_X
To al_S
1995 1998 2001 2004 2007 2010 2013 2016 2019
Epoch (yea )
300
400
500
600
700
800
900
1000
1100
Flux Densi y (mJy)
J1945+7055
To al_X
To al_S
1995 1998 2001 2004 2007 2010 2013 2016 2019
Epoch (yea )
300
400
500
600
700
Flux Densi y (mJy)
J2245+0324
To al_X
To al_S
Fig. 5. Ligh cu e o o al flux densi ies o confi med CSOs (i da a a ailable). The 8.4-GHz o al flux densi ies (To al_X) a e shown as black
do s and 2.3-GHz (To al_S) a e displayed as g ay do s
A icle numbe , page 23 o 28
A&A p oo s:
manusc ip no. ou pu
Fig. 6. P ope mo ion o diffe en componen s in each confi med CSO.
A icle numbe , page 24 o 28
T. An , Y. Zhang , S. F ey, W.A. Baan and A. Wang: Iden i ying CSOs wi h Gaia and VLBI
‘
Fig. 7. P ope mo ion o diffe en componen s in each co e–je sou ce.
A icle numbe , page 25 o 28
