z<4 Quasar pair 周囲の銀河密集度測定
尾上匡房 (総研大D2)

on behalf of HSC Project 168: “Galaxy Environment around Multiple QSO Systems”
2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

✦ BackgroundOutline-Quasar environment studies (QSO 2PCF, LAE/LBG clustering
around z>6 QSOs, semi-analytical simulation)-Low-z Multiple QSO System Studies✦ z<4 Multiple QSO System Study with HSC-SSP-

Sample & Method-Preliminary Result--z~4 QSO pair environments using g-dropout-z<2 QSO pair environments using photo-z
Future Prospects & Summary

2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

2/18

QSO Quasar
Triggering(QSO)
Mechanism
QSO phase

Alexander&Hickox+12•✦•

One of the most luminous objects in the Universe

A well-accepted trigger of quasars: Major mergers of gas-rich galaxies

Powered by super-massive blackholes (MBH~10^6-10 Msun)

Then, they should be good probes of rich environments inside massive dark
mattermajor
haloesmergers
where suchmerger
events frequently happen• Galaxytriggerquasars,➡

•

Good probes of rich environments inside massive dark matter haloes2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

3/18

QuasarTwo-pointClustering
Quasar Two-point Clusteringr0: correlation length

SDSS-Main

McGreer+16

BOSS

Eftekharzadeh+155Higher-z quasars
cluster[Shen+07,McGreer+16]-•Higher-z
quasarsmore
morestrongly
stronglycluster[Shen+07,McGreer+16]• Quasarenvironments- Quasararemoremorebiased
at higher-z?
environments arebiased
at high-z?
- The
correlation
gets flattenedat [Eftekharzadeh+15]z>2? [Eftekharzadeh+15]• Onlyfor most luminous
quasars?
2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

4/18

Overdensity
Quasars
Overdensityaroundaround z>6z>6 Quasar
ObjectObjectFoV[pMpc2] Technique
Technique Overdense?
Overdense?
zz FoV[pMpc2]

ULASJ0203+0012 5.72
5.72
ULASJ0203+0012
SDSSJ1306+0356 5.99
5.99
SDSSJ1306+0356
SDSSJ1030+0524 6.28
6.28
SDSSJ1030+0524
SDSSJ0338+0021 6.43
6.43
SDSSJ0338+0021
ULASJ1120+0641 7.08
7.08
ULASJ1120+0641
...
...

5.6
LAE
5.6
LAE
1.4
LBG
1.4
LBG
3.7
LBG
3.7
LBG
83.3
LBG
83.3
LBG1.4 Simpson+14
LBG
1.4LBGcf. ) Kikuta-san’s poster (at z~5)

#Kikuta-san isis now
now working
working onon thisthis analysis
analysis forfor another
another z~5z~5 quasar
quasar#Kikuta-sanEven at the highest-z, different results
havereporteddiﬀerent
Evenbeen
at highest-z,highest-z,
diﬀerent ﬁndings
ﬁndings
Even
atDifferent
technique,depth,
FoV-have
have been
been reported
reported
could
bepartof
thereasons•• Diﬀerent technique, depth, ﬁeld

Diﬀerent technique, depth, ﬁeld
coverage isis part
part ofof thethe reason
reasoncoverage➡Extremely luminous z>6 quasars emerge
AGN feedback,feedback, obscuration
obscuration•• AGNin both rich and normal environments?

00
nono00
yes
yes00

Ref
Ref
Banados+13
Banados+13
Kim+09
Kim+09Willott+05
Willott+05
Utsumi+10
Utsumi+10
Simpson+14Simpson+14

and more…
Courtesy ofof C.Mazzucchelli
Courtesy
Courtesy C.Mazzucchelliof C.Mazzucchelli

Simpson+14
LBG
z=7.1 QSO

LBG

LBG

10”

5/18

Why Is There No Clear Sign of Overdensity?
1.Quasar host haloes are not as massive as expected
2.Negative feedback suppresses galaxy formation in their proximities
Correlation
betweenenvironments
andQSOs
3.Most galaxies are dusty and obscured
SDSS DR12 QSO→ 216(96)QSOs in HSC-wide region at z=3.3-4.5 (3.6-4.1)
histogram of the signiﬁcance which QSO exist on

4.Overdense structure is very extended (>10pMpc?)
6030

216 QSOs at z = 3.3 - 4.5

50

QSO

96 QSOs at z = 3.6 - 4.1

25

QSO

RandomRandom

4020NNSee Uchiyama-san’s result!!
301520101050-4-202Significance40-4-202
SignificanceKS test P-value ~ 0.8
KS test P-value ~ 0.9
2016/06/02 Galaxy Evolution Workshop@ Tohoku
QSOs
do notUniv.
exist on > 4σ regions

46/18

Radio-loudness
isthekey?
Radio-loudness is the key?
5GHz luminosity

radio-loud

z=4.5

Radio Galaxies
Quasars
Allradio-quiet
z=2.2

Sikora+07

B-band luminosity

z=3.0

Orsi+15

Host halo mass

Two distinct radio emission properties: radio-loud/quiet AGN- Radio-loudAGNs trace overdense region quite well [e.g.Venemans+07, Hatch+14]
has been suggested that radio-loud AGNs trace overdense region quite well [cf. Venemans+07]- Host Itmass
range of radio-quiet AGNs seems wider than that of radio-loudAGNs. The host halo mass range of radio-quiet AGNs seems wider than that of radio-loudAGNs. Thus, radio--quiet
AGNs could reside in normal environments➡ quasar can emerge in normal environments [e.g. Orsi+15]
••

•

!

7/18

Situation is Too ComplicatedWhat we need is•

To observationally qualify quasar environment based onstatistics (beyond case studies!)•Sufficient sample size, FoV, depth

Wide and deep survey can overcome the current problems➡ Subaru/HSC-SSP Survey !

8/18

HSC Project 168 (PI: M.Onoue)

Galaxy Environment around Multiple QSO Systems✦Extreme system: Quasar Multiples
QSO
QSO

QSO
QSO

QSO
QSO

QSO
QSO

Star: z<2 QSO pairs, Circle&dot: galaxies
Contour: Galaxy Overdense Significance- In this study, we examine proto-clusters ina quasar point of view
- We examine the widely accepted yet notobservationally confirmed assumption thatquasars trace proto-clusters by focusing
on extreme multiple environments- Redshift: 0<z<4➡HSC survey is well-suited for this study!
(Wide: 1400 deg2 , rlim,5σ~26)✦First systematic study of quasar
multiples at high redshift!

2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

9/18

Quasar Pair Studies at z<1
QP 0110-0219
z=0.96, Rtrans=0.6Mpc

z=0.736, Rtrans=90kpc

Low-z Quasar pairs do notnecessarily
14 QSOpairs at z<0.85
reside in rich environments(Single-QSO)

Cumulative

photo-z selectedgalaxies

Boris+07

Sandrinelli+14

2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

10/18

Quasar Quartet at z~2 [Hennawi+15, Science]
Connection between
Quasar - CGM - Protocluster ?

Giant Lyα nebulae(~300kpc, LLyα=2.1e+44 erg/s)

Cumulative overdensityof LAEs/LBGs
SDSS J0841+3921

HzRG

s&LABsRadio-quiet QSO

2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

sQuasar Multiple Sample Selection• SDSS DR12 QSO Catalog & Hennawi+06,+10 & McGreer+16• Rtrans<4pMpc (typical massive cluster size, Chiang+13)• dvpara<3500km/s (at z>3)• 110(11) z>3.2 pairs in all (S15B) HSC-Wide&Deep ﬁeld
• ~4000 (~900) pairs in all redshift range
HSC-Wide ﬁeld

z>3

RA[h]

Redshift

Rtransdvparaz

Rtrans [pMpc]

dvpara [km/s]

MethodMethod• Overdensity measurement: fixed aperture method (cf. Toshikawa+16)
・Measurements of overdensity : Fixed aperture method

・Measurements of overdensity : Fixed aperture method

Overdensity measurement: aperture method
1. distribute apertures1.
distributeapertures
caluculate average・・・
and sigma in 2by2deg^2ﬁeld
r =1.8’(~0.8pMpc@z~4)
・・・
dropout/photo-z
2. count g-dropouts
nearby the pair, and zoom up thepair
ﬁeld
2. selected
count g-dropouts
galaxies(6by6pMpc^2 3. estimate ave and std
3. estimate ave and std

4. determine signiﬁcance5.4.zoom
up thesigniﬁcancepair ﬁeld
determinemost>4σoverdense regions
aredensities
expected
What is the suitableradiusof measurementsof local? to evolve

into massive clusters (>1014Msun @ z~0) for g-dropouts

What is the suitable radius of measurements of local densities ?

QSO
QSO

222deg
2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

6 6 pMpc2

Preliminary Result
1.z~4 (radio-quiet) quasar pairs (N=2, g-dropout)
2. z<2 pairs (N=250, photo-z)

14/18

G-dropout Density Map
QSOP J2209+0111 (z1=3.45, z2=3.75)

QSOP J2214+0109 (z1=3.59, z2=3.57)

Rtrans=1.04 pMpc, dvpara=3369 km/s

Rtrans=1.79 pMpc, dvpara=120 km/s

QSO
QSO
QSO

3.9σ

QSO

4.3σ

aperture size (r=1.8’)

A giant protocluster candidate found2016/06/02 Galaxy Evolution Workshop @ Tohoku Univ.

circle: i<25
dot: i>25
15/18

z<2 QSO Pair Field (N=250)(normalized)

z=1.28, Rtrans=1.10pMpc, dv=697.6km/s

QSO Pair: SDSS DR12Galaxy: S15B photo-z catalog (Mizuki)- zgal, photo=zQSOP±0.05(1+zQSOP)- z_median_conf > 0.2- SN_r,i > 5 (cmodel)

4.58σ(normalized)

KS test: p-value=0.71

Close

z=1.14, Rtrans=1.25pMpc, dv=15.4km/s

KS test: p-value=0.098
p-value=0.71

Not all, but close pairs prefer dense regions at low-z

16/18

Future Prospects✦ VLT/VIMOS Follow-up observation of the promising proto-cluster

candidate at z~4(spec-z determination, Lyα emission properties)✦ Extend this study to all redshift range using photo-z✦ It would be interesting to check the presence of other objects such as

highly obscure galaxies (DOGs) and radio-loud AGNs in the pair fields✦ Compare pair fields with single-QSO fields✦ Constructing fainter quasar pair sample using HSC photometry catalog

We aim to investigate the role of quasars in thegalaxy evolution from a unique point of view
17/18

Summary✦ We have started z<4 quasar multiple environment study with the HSC-SSP survey to investigate whether quasars really trace overdense regions✦ From the current sample for which g-dropout technique is applicable(only 2), we have already found a promising giant proto-cluster traced bya close quasar pair. Its follow-up observation will be in near future.

✦ Based on photo-z, we find z<2 close quasar pairs are likely to reside in

overdense regions, which suggests they are better proto-cluster tracers
than single quasars✦ We aim to derive a unique constraint on how quasars relate to their

host haloes and surrounding galaxy formation

18/18