Observational Studies on Transient
Objects with Hiroshima 1.5-m
Opt-NIR Telescope and Others
Koji S. Kawabata (Hiroshima Univ.)
on behalf of Kanata team1Index• `Kanata’1.5-m Optical Telescope– Overview: Higashi-Hiroshima Observatory– Instruments• Strategy of Kanata Telescope– Multi-wavelength, Multi-mode– Representative Results• Blazars and related objects• Microquasars• GRBs• Summary and Future Prospects2`Kanata’1.5-m Optical Telescope3

Higashi-Hiroshima Observatory•Found in 2006; operated by Hiroshima University•Only 25 min by car from campus (503m above sea level)•~40% observable nights•Better seeing condition (median FWHM ~1.2 arcsec)•Sky brightness R=19-20 mag/arcsec2 in dark nights
Kyoto

Hiroshima Univ. Campus

Hiroshima
HHO

HHO(Higashi Hiroshima Observatory)

4

OkayamaOAOOsaka

Red region:
Sunny >2000hr/yrHigashi-Hiroshima Observatory: Aim
Multi-wavelength and/or Multi-band study forvariable, transient objects
Gamma-ray, X-ray and
Optical/NIR Observations
GRB, XRB, AGN, etc

1.5m Optical/NIR telescope, Kanata (2006-)
Gamma-ray satellite (Fermi 2008-)
X-ray satellite (Suzaku 2005-, Astro-H 2016-）© JAXA© NASA5© JAXA5

HE & Opt/NIR Obs. Astronomy group
HE (X-ray and gamma-ray) Astronomy Group––––––Fukazawa, Yasushi (Prof)
Mizuno, Tsunefumi (Assoc. Prof)
Takahashi, Hiroshitsu (Assist. Prof)
Ohno, Masatoshi (Assist. Prof)
Tanaka, Yasuyuki (S.-A. Assist. Prof)
Kitaguchi, Takao (S.-A. Assist. Prof)

Optical and Near-Infrared Astronomy Group, 2004–––––Yoshida, Michitoshi (Prof)
Kawabata, Koji (Assoc. Prof)
Uemura, Makoto (Assoc. Prof)
Akitaya, Hiroshi (S.-A. Assist. Prof)
Utsumi, Yousuke (S.-A. Assist. Prof)

Specially Appointed Professor in the group– Miyama Shoken (S.-A. Prof)– Ohsugi, Takashi (S.-A. Prof)(Theoretical Astronomy group )– Kojima, Yamamoto, Okabe
6

Telescope and Instruments
Nasmyth focus#2

Nasmyth focus#1

High Speed-readout
spectrograph

HOWPol 2009-

Opt Imaging： FoV 15′ΦOpt ImagPol： One-shot type
Spec： R~400(400-1050nm)
We-Do-Wo type Wollaston

FoV: 2.3’×2.3′
Wavelength res.: R = λ/Δλ =9-70（400-800nm）、
150（430-690nm）~30 frames/sec

Cassegrain focus`Kanata’ Telescope•Successor of IR simulator ofSubaru telescope•1.5mΦ main mirror• Azimuth rotation speed : 5°/sec,
2-4 times faster than normal 1-m
size telescopes. (merit in highresponse observation (e.g. GRBs)`One-shot polarimetry’is available --- Uniquepotential for quickly-variableobject like GRB afterglows

HONIR : 20121 Optical band + 1 （future 2) NIR band (simultaneous)
Opt+NIR Imaging： FoV 10′×10′
Opt+NIR Spec： R~400-500
Opt+NIR ImagPol/SpecPol

Maximizing information by single observation
7

Observational Targets with Kanata telescope 1
CVsBlazars

SNeGRBs

OthersXRBs

Year (paper #)2010 Aug-2011 Jul(3 papers)
Follow-up obs. for
Fermi, MAXI, etc.

2009 Aug-2010 Jul(10 papers)
2008 Aug-2009 Jul(6 papers)
2007 Aug-2008 Jul(4 papers)
After Fermi launched,extended polarimetricmonitoring of blazars

2006Aug-2007 Jul

CVs were initial main
targets.

Total Observation time (hr/year)
8

Observational Targets with Kanata telescope 2

Recent years
Others(YSOs)XRBs

Blazars/AGN

GRBs

Multi-wavelength study
with HE photons (+radio)

Supernovae

9Number of Refereed Papers using Kanata Telescope

54 papers10

A member of Opt/NIR Inter-University
Cooperation Network: OISTER (2011-)

埼玉大(Japan)
16 tels.
0.5-2m(Chile)1 tel.
1m(South Africa)
1 tel.
1.4m

A few Campaign Observation in a year
11

Strategy of Kanata Telescope

12

Discrimination from other telescopes• Transient phenomena– Requiring high response system and/or extendedobservations (being hard for large telescopes)• Multi-wavelength– Coordinated with X/Gamma-ray observations
supported by high-energy (and theoretical) people.

• Multi-mode– Simultaneous Opt/NIR observation including
polarimetry and spectroscopy, maximizing information
gaining from a single observation.

13

Comment for multi-wavelength observation• There are large differences in observing
technique and conditions between Opt/NIR andX/Gamma-ray regimes.
• Special skill is required for planning an effective
multi-wavelength collaborative study.
• For long-lasting collaborative study, daily
cooperation (, mutual understanding, andinterdependence, …) will be necessary.
• Our group may luckily satisfy it, because it hasestablished supposing daily education andcollaboration in a single unit.
14

Comment for multi-mode observation• Polarimetry has been focused in ourinstrumentation and observation.
• Generally, `polarization of light’ is minor subject
in astronomy (although I disagree with it) andoptical instruments having capability ofpolarimetry is still rare.
• It is quite rare that a polarimeter is always
attached to telescope (that is, polarimetry iscapable every night at the telescope), even amongworldwide 1-2-m class small telescopes.

15

Instruments
Nasmyth focus#2

Nasmyth focus#1

High Speed-readout
spectrograph

HOWPol 2009-

Opt Imaging： FoV 15′ΦOpt ImagPol： One-shot type
Spec： R~400(400-1050nm)
We-Do-Wo type Wollaston

FoV: 2.3’×2.3′
Wavelength res.: R = λ/Δλ =9-70（400-800nm）、150（430-690nm）~30 frames/sec

Cassegrain focus`Kanata’ Telescope•Successor of IR simulator ofSubaru telescope•1.5mΦ main mirror• Azimuth rotation speed : 5°/sec,2-4 times faster than normal 1-m
size telescopes. (merit in highresponse observation (e.g. GRBs)`One-shot polarimetry’is available --- Uniquepotential for quickly-variableobject like GRB afterglows

HONIR : 20121 Optical band + 1 （future 2) NIR band (simultaneous)
Opt+NIR Imaging： FoV 10′×10′
Opt+NIR Spec： R~400-500
Opt+NIR ImagPol/SpecPol

Maximizing information by single observation
16

Multi-wavelength Observation Sample 1:Blazars and related objects

17Blazars

cold gas
jethot gas

black holeaccretion
diskplasma torus

Blazars are believed to be AGN seen along the jet axis.
→ Synchrotron radiation would dominate the flux at
IR/optical wavelengths

18

SED of Blazars

Low-peak (LSP)

Synchrotron peakIntermediate-peak (ISP)

19

Radio

High-peak (HSP)(BL Lac objects)

Inverse Compton peak

(FSRQ)

Luminosity

Relativistic beaming;brightened by δ^4 ~10,000 times

Emission from the jet dominatesfrom radio through gamma-ray;
rapid and large amplitude variability
and strongly polarized light

Fossati+98

log v (Hz)Gamma-raySynchrotron –Self Compton (SSC)
External Radiation Compton (ERC)

luminosity

Emission model of high energy partHigh-peak : Mrk421 Abdo+11

synchrotron

SSC

Freq [Hz]Kataoka+99

Abdo+10synchrotron

Emission at GeV regime
High-peak ： SSC
Low-peak ： ERC

ERC

Low-peak :PKS1502+106
SSC

20Freq (log v)

Kanata Blazar Photo-Polarimetry Campaign
We performed polarimetric campaign with Kanata telescope
and a simultaneous optical and NIR instrument, as a joint
observation with Fermi Gamma-ray satellite
in 2008-2010.
42 blazars (13 FSRQs, 8 LSPs, 9 ISPs, and 12 HSPs; theclassification based on Abdo et al. 2010) are monitored in V,
J, and Ks-band.
Most comprehensive polarimetric data set obtained.
Ikejiri et al. 2011

Target Blazars
PKS 0048
S2 0109
MisV1436
PKS 0215
3C66A
AO 0235

QSO 0324
1ES 0323
PKS 0422
QSO 0454
1ES 0647
S5 0716

PKS 0754
1ES 0806
OJ 49
OJ 287
S4 0954
3EG 1052

Mrk 421
RGB 1136
ON 325
ON 231
3C 273QSO1239
213C279
OQ 530
PKS 1502
PKS 1510
PG 1553
Mrk 501

H1722+119
PKS 1749
S5 1803
3C371
1ES 1959
PKS 2155

BL Lac1ES 2344
3C454.3

Flux-color correlation
3C 454.3

PG 1553+113

Color-mag.
diagramColorV mag

3C 371

Ikejiri et al. 2011

`Bluer when brighter’ `Bluer when brighter’ in brighter phase (16%)
trend in the whole data (In faint phase, hot disk component is dominant)
(72%)
22

Flux-polarization correlation
AO 0235+164

MisV1436

OJ 49

FluxPol.
degreePol.-fluxcorr.

positive corr.

positive corr. + othernegative corr.
Ikejiri et al. 201145%
23

Rotation of Linear Polarization Angle
PKS 1510-089

3C 66AV magPAobs
PA180
PAshiftaround origin

around origin

around average Typically, 1020°/dayaround average

Our dense monitoring (every ~3 days) revealed hidden
characteristics of variation of polarization vector.
QUdiagram

Variation of polarization
vector is not random but
systematically rotating 24

Non-zero averagepolarization
Ikejiri+ 2011

Multi-wavelength study in 3C 279
MW Light Curve and Opt. Polarization
γ-ray

SED
Flux

X-ray

OpticalOpt. Polarization

PA of Opt. Polarization
振動数[Hz]Radio

Date [MJD]
25

Abdo+10, Hayashida+12; Itoh private comm.

Multi-wavelength study in 3C 66A
Itoh+13

ISP (z = 0.444)
Flare in 2008 Sep
Extended monitoring with
Fermi/LAT & Kanata tel.

Gamma-ray flux

NIR flux

3C 66A Gamma-ray image
Optical flux

PA(deg)Pol (%)

Opt/NIR color

Itoh+13

2008-08
26

Optical polarization

Polarization PA

Date [MJD]

2010-02

Inverse Compton Scattering: External radiation source

Period 1  Period 4.
Optical flux: Increased by 2 times
Gamma-ray: No variation
Variation of ERC radiation
Shikora et al. 2007

(B = 0.23 [G], Γ=50, R = 1.5 × 1016 cm are assumed by spectral fitting; Abdo+10)

EpochPeriod 1Period 4

Uext [𝟏𝟏𝟎𝟎−𝟕𝟕 𝒆𝒆𝒆𝒆𝒆𝒆 𝒄𝒄𝒎𝒎−𝟑𝟑 ]
9.04
4.54

Suggesting different environment/location for radiation
soueces for Period 1 (more ER) and 4 (less ER)
27

Active phase monitoring in CTA 102
FSRQ (z = 1.037)

Itoh, Fukazawa, Tanaka+13

Flare observed on
19 Sep 2012 Optical report (ATel #4397)
21 Sep 2012 GeV report (ATel #4409)

Started dense monitoring with
Kanata + OISTER

Two types of violent
variation in opticalpolarization observed.
Only polarizationdeg. flared.
28

Both flux and pol.
deg. flared.

Flare with polarization (MJD 56202)
Itoh, Fukazawa, Tanaka+ 13
Pre-existing emitting region
Total flux

First detection of simultaneous
flaring in both luminosity andpolarization within <1 day.
Polarization variation in Stokes QU

Polarized flux
Strongly polarized
emitting region emerged
Stokes U

MJD56202

Time [hour]

Emergence of newemission region?
Different direction ofpolarization vector
29

Stokes Q

Summary of our blazar monitoring across flaring
Itoh et al., private comm.
ObjectClass

Correlation ofopt and gammafluxes

Corr. of opt
flux and opt
polarization

Multi sitefor emitting
regionAlignmentof jet andpolarization

3C 66A

ISP△○○||Mrk 421

HSP×××||CTA 102

FSRQ

○△○

⊥

AO
0235+164

LSP

○

○×||

GB6 1310

FSRQ

○○×--

LSP: Low-peaked, ISP; Intermediate, HSP; High-peaked FSRQ(LSP); Flat spectrum radio quasar
Mrk 421 jet; VLBA

Condition differs object to object…
30

Piner & Edwards (2005)

Ongoing study (Itoh+ in prep.)More comprehensive study with Fermi and Kanata
FSRQLSPISP(*); Number of optical observations
Red; GeV bright source
HSP

RL-NLSy1

3C 454.3 (498)BL Lac (539)

S5 0716+714 (628)

Mrk 501 (244)1H 0323+342

3C 273 (332)

OJ 287 (413)3C 66A (487)

PG 1553+113 (225)

PMN J0948+0022

3C 279 (177)

AO 0235+164 (93)

1ES 1959+650 (202)

PKS 2155-304 (161)

PKS 1749+096 (163)

OJ 49 (70)

S2 0109+22 (102)

Mrk 421 (74)

3C 371 (124)

S4 0954+658 (5)PKS 0048-097 (63)

ON 325 (56)RX J1542.8+612 (113)

1ES 1218+304 (3)ON 231 (48)

1ES 0806+524 (54)

OQ 530 (19)H 1722+119 (66)

PKS 1510-089 (110)
Mis V1436 (106)

PKS 0422+004 (42)

CTA 102 (92)

1ES 2344+514 (33)

PKS 1502+106 (76)

1ES 0647+250 (24)

QSO 0454-234 (28)

1ES 0323+022 (21)

S5 1803+784 (35)
PKS 0754+100 (28)
PKS 0215+015 (5)GB6 J1239+0443 (5)• Bright in GeV gamma-ray• Observable with Kanata telescope• Flares have been observed
31Multi-wavelength Observation Sample 2:
X-ray binary; Micro quasars

32

X-ray binaryjet synchrotron
IR OptAccretion disk
Binary including BH or NS
XTE J1118+480; Markoff et al (2001)• It has been claimed that NIR light is produced by jet. (Most X-raybinaries locate near the milky way, and the optical light is heavily
absorbed, but NIR light is much less absorbed.)• Thus, jet can be probed by NIR observation (as well as X-ray and radio
observations)
33

GRS 1915+015 as `microquasar’• Superluminal motion in radio (VLBI)→ High-velocity jet → Called as microquasar• BH mass 14±4 M from NIR spectroscopic period (Greiner et al. 2001)• A time-sequential flare among X-ray, NIR and radio wavelengths isfound, explained by disk-jet model (Mirabel et al. 1998)• But, the observational material for accretion and jet physics is stillpoor.
34

Anti-correlation in X-ray and NIR
NIR photometric monitoring.
X-ray hardness ratio suggests
this binary is in soft state at
MJD 54320-54570.
Around MJD 54370, X-ray andradio flare appeared→ jet ejection
In contrast, NIR flux decreased.
(Time lag < 1d)

Possible jet ejection

NIR(Ks)Soft X

Hard X

Radio
Arai et al (2009)This NIR – X/radio anti-correlation continued during its
soft state (~250 d).
35What does the anti-correlation indicate?
jetIR Opt

KsAcc. disk

• NIR flux becomes redder at flare.
This suggests that the jet synchrotron
component is significant at flare, but thermal
emission from hot accretion disk dominates
NIR flux normally.

ReddenedH-Ks
Soft X

Arai et al (2009)• Why does NIR flux decrease at jet ejection?
Accretion disk disappeared temporally?
Coronal disk wind hides the disk in NIR?
Future NIR spectroscopy and/or polarimetry will give another insight.
36

Multi-wavelength Observation Sample 3:
Gamma-ray bursts and their afterglows37Afterglow of GRBs
A considerable fraction of GRBs (~30%)
show afterglows in optical wavelengths.
They are explained by synchrotron
radiation originated in an external shock
region where the relativistic jet interacts
with circumstellar matter.

Internal

afterglow

Meszaros 02
38

X-ray

Optical/NIR

Externalγ, X, Opt,
radioGRB

080413B Filgas+ 2011

Time since (sec)Expected geometry of magnetism and polarization
1.
2.

Totally random orientation of magnetism.
 Null polarization
Combination of coherent patches (scale length~ cτ). Within each patch, the magnetic field isordered. Normal jet may have ~50 patches.
 Constant polarization of ~10% (=70%/√N)2.
jet～c τpolarized

3.

(e.g., Gruzinov & Waxman 1999)

4.

Axi-symmetric polarization pattern due tocompressed, tangled magnetic field, coupledwith relativistic `beaming’ and `occultation’ ofemitting region.
 Variable polarization of p=0-10% from obliqueline of sight (e.g, Sari+ 1999; Rossi+ 2004)
Large scale ordered-magnetic field in (nothydrodynamic jet, but) Poynting-flux dominatedjet (e.g, Lyutikov+ 2003)
 Large polarization (up to ~50%)
39

jetunpol.
polarized

Polarization

3.

Time since GRB
Rossi+ 04

List of Kanata optical polarimetry for GRBs
GRB
triggert1

GCN Expos.
t3-t1 t3-t2
receive start
(s)
(s)
t2
t3

GRB 091208B

9:49:58

9:50:24 9:52:27

149

123

Yes

GRB 111228A

15:44:43 15:45:33 15:47:25 162

112

Yes

GRB 121011A

11:15:30 11:16:09 11:17:02

53

NoGRB 130427A

7:47:57

7:49:15 11:40:26 14027 13949

NoGRB 130505A

8:22:28

8:22:51 10:46:08 8643

8620

NoGRB 140629A

14:17:30 14:17:46 14:18:43

57

No

92

73

Polarized?

We have the record of earliest observation (<~100s aftergamma-ray trigger) for GRB afterglow in polarimetry(091208B, 121011A, 140629A).
40

GRB 111228A (z=0.714)

Takaki, Toma, KK+, submitted

Optical afterglow shows significant temporal polarization change.
GRB 111228A: Strongly polarized
Katsutoshi Takaki will give a talk on the study of this GRB afterglow
on third day of this GRB conference.
41

GRB 140629A (z=2.3)
T90 (15-350keV) = 75.6±12.7sec

Galactic 𝐴𝐴𝑉𝑉 = 0.022 ; upper-limit 𝑝𝑝𝑀𝑀𝑀𝑀 ~0.07%

Polarimetry began at 𝑇𝑇0 + 73 s
(22 s in rest frame)
The record of earliest polarimetry ever!

𝑝𝑝 = 1.8±1.1 % at T0+73 s to 185 s
𝑝𝑝 = 1.5±1.8 % at T0+198 s to 436 s
𝑝𝑝 = 2.8±6.4 % at T0+7456 s to 8618 s

GRB 140629A: Unpolarized (or onlyweakly polarized)
42Takaki+, in prep.

Other early afterglow polarimetry
Mundell+ (2013), Nature

Polarization (%)

RINGO2
RINGO2/CAFOS
RINGO
HOWPolRINGOISAAC/FORS2
FORS1

Time from GRB (sec)Earliest afterglow is generally strongly polarized?
43

Other early afterglow polarimetry w/ HOWPol data

Polarization (%)

Mundell+ (2013), Nature
RINGO2
RINGO2/CAFOS
RINGO
HOWPolRINGOISAAC/FORS2
FORS1111228A
091208B
121024 (Wiersema+ 2014)

140629A 121011A

130427A

130505A

Time from GRB (sec)Earliest afterglow is generally strongly polarized?
－ No.
44• Summary and Future Prospects

45Summary of Kanata telescope• Originally constructed for multi-wavelength observation• Basic, multi-purpose instruments have been developed
and are always stand-by for observation• Unique results have been provided for optical/NIR
photometry/polarimetry monitoring for Blazars, XBs,GRBs, supernovae, etc.

46

Future Prospects with Kanata telescope• Collaborative Study with future telescopes/satellites(Small telescopes still can contribute featuring unique modes.)

CTAAstro-H• Search and Follow-up of Optical Counterpart ofGravitational Wave Source (a member of J-GEM)• Promoting a future project: SGMAPFirst polarimetric survey in northern hemisphere~104 stars (existing catalogue)→ 106-107 stars
Supplementary with Gaia astrometry(including distance) catalogue (~2021)

Seeds for future study
47