AGN Jet Workshop 2020

The relation between the accretion process
and the Faraday rotation of the jet of blazars
112

1Naeun Shin, Minchul Kam, Jongho Park, Sascha Trippe
1 Seoul National University, Korea
2 Academia Sinica Institute of Astronomy and Astrophysics, Taiwan

N. Shin @ SNU, Korea

1

MIT Kavli Institute for Astrophysics and Space ResearchContents
1. Introduction
2. Data
3. Results & Discussion
4. Future

2

AGN Jet Workshop 2020

Introduction

N. Shin @ SNU, Korea

3

AGN Jet Workshop 2020

Jet dynamics

CentralBlack hole
4

MIT Kavli Institute for Astrophysics and Space Research

AGN Jet Workshop 2020

Jet dynamics

Magnetic ﬁeld
CentralBlack hole
5

MIT Kavli Institute for Astrophysics and Space Research

AGN Jet Workshop 2020
Gabuzda, 2017Blazars

N. Shin @ SNU, Korea

6

AGN Jet Workshop 2020
Gabuzda, 2017Blazars

N. Shin @ SNU, Korea

7

AGN Jet Workshop 2020

Multiwavelength Observation of Blazars

Rotation measure(RM) is
integrated electron density
and magnetic ﬁeld
along the line of sight.
N. Shin @ SNU, Korea

8

AGN Jet Workshop 2020

Inclination between two EVPAs= Rotation Measure

N. Shin @ SNU, Korea

9

AGN Jet Workshop 2020

EVPAs change even in one month-> Multi-frequency data needed toobtained in similar period

N. Shin @ SNU, Korea

10

AGN Jet Workshop 2020

Variability of the AGN jet-> Multi-epoch observation is needed

N. Shin @ SNU, Korea

11

AGN Jet Workshop 2020

Find the relation
between the jet and the accretion rate
The jetRotation
Accretion rate
power
MeasureElectron density
Magnetic field strength
N. Shin @ SNU, Korea

12

AGN Jet Workshop 2020

Optical Subclass of Blazar

Flat spectrum Radio Quasar (FSRQ)& BL Lac Object (BLO)
FSRQs are usually bright and believed tohave larger accretion rates than BLOs
Subclass of blazar can be a informationof the accretion rate!

N. Shin @ SNU, Korea

13

AGN Jet Workshop 2020

Find the relation
between the jet and the accretion rate
The jetRotation
Accretion rate
powerMeasure

FSRQs
BLOs
N. Shin @ SNU, Korea

Electron density
Magnetic field strength14

AGN Jet Workshop 2020

Statistical studies of FSRQs & BLOs using rotation measure
8~15GHz (Hovatta et al. 2012, Zavala & Taylor, 2004)

The inner region of the jet near the core
Can be observed with higher frequency

N. Shin @ SNU, Korea

15

AGN Jet Workshop 2020

Data & Targets

N. Shin @ SNU, Korea

16

AGN Jet Workshop 2020

KVN monitoring program

We used monthly monitored data observed
simultaneously at 22 (K), 43 (Q), and 86 (W) GHz by
the Korean VLBI Network (KVN) from the
Plasma-physics of Active Galactic Nuclei project(PaGaN).
N. Shin @ SNU, Korea

17

AGN Jet Workshop 2020

N. Shin @ SNU, Korea

In 6 epochs from 2016 to 201818

AGN Jet Workshop 2020

Results

N. Shin @ SNU, Korea19

AGN Jet Workshop 2020

Result 1:
FSRQs have larger RMs than BLOs
Result 2:
Similar slope between FSRQ & BLO in freq - RM ﬁgure

Result 3: High accretion with large RM in FSRQ

N. Shin @ SNU, Korea

20

AGN Jet Workshop 2020

RM of optical subclasses

N. Shin @ SNU, Korea

In logarithmic scale

21

AGN Jet Workshop 2020

RM of optical subclasses

In logarithmic scale

The median value of RM of FSRQs is larger than BLOs
22 ~ 43 GHz: 2.7 / 43 ~ 86 GHz: 4.7 times larger
BLOs have less surrounding materials -> less density, low B of the jet
N. Shin @ SNU, Korea

22

AGN Jet Workshop 2020

RM of optical subclasses

K-S test for 22 ~ 43 GHz: p value = 0.30
K-S test for 43 ~ 86 GHz: p value = 0.02
In higher frequency, the two groups are signiﬁcantly separated!
N. Shin @ SNU, Korea

23

AGN Jet Workshop 2020

RM of optical subclasses

The median value of RM of FSRQs is larger than BLOs
43 ~ 86 GHz: 4.7
22 ~ 43 GHz: 2.7

8 ~ 15GHz : 1.4 times larger (Hovatta et al. 2012)
The gap of two groups become larger in a higher frequency.
N. Shin @ SNU, Korea

24

AGN Jet Workshop 2020

RM_fsrq
RM_blo● The difference increase
along the frequency● With higher frequency, we
can observe the deeper
region of the jet

Observing frequency(Geometric mean)
N. Shin @ SNU, Korea

25

AGN Jet Workshop 2020?
RM_fsrq
RM_bloObserving frequency(Geometric mean)
N. Shin @ SNU, Korea● The difference increase
along the frequency
Lineary?
Increase continuously?
Saturation?
Decrease in high freq?

● High frequency datais needed
26

AGN Jet Workshop 2020

Result 1:
FSRQs have larger RMs than BLOs

Result 2:
Similar slope between FSRQ & BLO
in freq - RM ﬁgure
Result 3: High accretion with large RM in FSRQ

N. Shin @ SNU, Korea

27

AGN Jet Workshop 2020

● RMs of each targets are averaged
for 6 epochs.
● Both show the increasing RMs
with higher rest frame frequencies.

Rest frame frequency
N. Shin @ SNU, Korea

28

AGN Jet Workshop 2020

FSRQ: 0.0087 x + 3.25
Error: 0.018, 1.89

BLO: 0.0087 x + 3.04
Error: 0.03, 2.27

● FSRQs and BLOs show
similar increase of RM as afunction of frequency.
(with large scatter)
N. Shin @ SNU, Korea● Need more data points!
29

AGN Jet Workshop 2020

FSRQs usually have larger RMs than BLOs-> because of a high redshift?
FSRQs are usually brighter than BLOs-> can be observed in higher redshift
Observed in higher rest frame frequency
Observing deeper region of the jet-> have larger RM than BLOs

N. Shin @ SNU, Korea

30

AGN Jet Workshop 2020

1) FSRQs and BLOs have similar trendof increase in freq - RM relation-> FSRQs and BLOs have similarmagnetic ﬁeld structure of the jet2) Larger RM of FSRQs can be a red
shift effect?

N. Shin @ SNU, Korea

31

AGN Jet Workshop 2020

Result 1:
FSRQs have larger RMs than BLOs
Result 2:
Similar slope between FSRQ & BLO in freq - RM ﬁgure

Result 3: High accretion with large RM in FSRQ

N. Shin @ SNU, Korea

32

AGN Jet Workshop 2020

Compare RMs with optical properties

N. Shin @ SNU, Korea

33

AGN Jet Workshop 2020

● Both FSRQs and BLOs showrandom distribution between
RM and BH mass
● BH masses are obtained withvarious methods

N. Shin @ SNU, Korea

34

AGN Jet Workshop 2020

The disk luminosities in a unit ofEddington luminosity(Park & Trippe 2017)
While BLOs show a random
distribution but FSRQs show a positive
relation between RM and L/Ledd

N. Shin @ SNU, Korea

35

AGN Jet Workshop 2020

Discussion: FSRQ & BLO
Mass of the BH: past accretion
history

Disk Luminosity: current accretion rate
N. Shin @ SNU, Korea

Electron density ↑B strength ↑Only in FSRQs36

AGN Jet Workshop 2020

FutureN. Shin @ SNU, Korea

37

AGN Jet Workshop 2020

Future 1: Increase the data frequency range
Sub-mm VLBI data is hard to getBlazars are usually very compact
Most of polarization ﬂux in the beam size
is originated from the coreSingle dish data is also feasible
N. Shin @ SNU, Korea

38

AGN Jet Workshop 2020

Future 1: Increase the data frequency range
Current KVN frequency band
22, 43, 86, 129 GHzMOJAVE Project
Archeive

Calibration finished

15GHz

N. Shin @ SNU, Korea

39

AGN Jet Workshop 2020

Future 1: Increase the data frequency range

22, 43, 86, 129 GHz
e-KVN: 230GHz
SMA: 230 & 345GHz
JCMT: 352GHz

N. Shin @ SNU, Korea

40

AGN Jet Workshop 2020

Future 1: Increase the data frequency range● Increased numbers of the data points-> get smaller scatter● More data in higher frequency-> find the behavior of FSRQs andBLOs in wide frequency range

N. Shin @ SNU, Korea

41

AGN Jet Workshop 2020

Future2 : The advanced sample set with limited zPrevious
7 FSRQs 0.5 < z < 1.55 BLOs 0.1 < z < 0.3Total

0.3 < z < 0.7

FSRQ

208BLO129● Increase the sample set● Select targets in similar redshift range
N. Shin @ SNU, Korea

42

AGN Jet Workshop 2020

Future2 : The new sample set with limited z

FSRQs withlower redshift

N. Shin @ SNU, Korea

BLOs withhigher redshift

43

AGN Jet Workshop 2020

Summary
1. The study of RM of FSRQs and BLOs can find the relation between
RM and the accretion states of central black hole
2. We used simultaneous multi-frequency data of 12 blazars from 22 to86GHz using KVN
3. FSRQs show larger RMs than BLOs when compared in observing
freq.
4. Both FSRQs and BLOs show similar trend in rest-frame frequency.
5. FSRQs with larger RMS have higher accretion rates.
6. We need more data points in higher frequency.
44

N. Shin @ SNU, Korea

AGN Jet Workshop 2020

Reference
Blandford, R. D., & Königl, A. 1979, ApJ, 232, 34
Cao, X., Jiang, D. et al., 1999, MNRAS. 307, 802
Chai, B., Cao, X., et al, 2012, ApJ, 759, 114
Ghisellini, G., Maraschi, L., & Tavecchio, F. 2009, MNRAS, 396, L105
Ghisellini, G., Tavecchio, F., Foschini, L., & Ghirlanda, G. 2011, MNRAS,414, 2674
Hovatta, T., Lister, M. L., et al. 2012, ApJ, 144, 105Liu, Y., Jiang, D., et al. 2006, ApJ, 637, 669
Sbarrato, T., Ghisellini, G., et al. 2012, MNRAS. 421, 1764
Shen, Y., et al. 2011, ApJ, 194, 45
Park, J., Kam, M., et al. 2018, ApJ, 860, 112
Park & Trippe, 2017, ApJ, 834, 157
Torrealba, J., Chavushyan, V., Cruz-González, I., et al. 2012, RMxAA, 48, 9Wang, J.-M., Luo, B., & Ho, L. C. 2004, ApJL, 615, L9Woo, J.H. & Urry, C.M., 2002, ApJ, 579, 530
Xie G. Z., Zhou S. B., Liang E. W., 2004, AJ, 127, 53
Zavala & Taylor, 2004, ApJ, 612, 749
Zhao, G.-Y., Algaba, J. C., et al. 2018, AJ, 155, 2645

N. Shin @ SNU, Korea