2019.11 初代星・初代銀河研究会 2019

galaxy environment
quasar environment
Nobunari Kashikawa(U Tokyo)

Environment
Illustrisz=8.5

Is quasar activity preferentially triggered in the density peaks?
How does quasar radiation affect on surrounding environment?
BH/QSO
Overdense region

Reionization topology

When and how was galaxy environmental effect emerged?

Does gas also trace underlying density field?
z=0Millenium

cluster
Underdense region

High-z protoclusters• Very rare
• Not enough sample of protoclusters beyond z=3• Most of them are found around RGs/QSOs~1000 protoclusters will be found at z~4 (g-dropout)→ diversity of protoclusters• Ultradeep/Deep layer (~27 deg2)~10-20 protoclusters will be found at each redshift→ redshift evolution of ~30 cluster members• various follow-up observations to reveal cluster formationand galaxy evolution. (spec., IR, radio, etc.)

Only ~20 PC at z>3
Overzier+ 16

HSC Protocluster search @z~4

XMM
2
179 PC candidates from 121deg

GAMA15H

15 degToshikawa, NK+ 18

g-dropout galaxies at z~4

Mass of z~4 PCs• Clustering of PCs• Abundance matchingObserved overdensity Predicted Mass function
distribution

Mhalo~1-2x1013 Msun
Observed number density

Toshikawa, NK+ 18

Descendant halo mass at z=0:

Rest-UV LF of PC galaxies at z~4• Significant excess at the bright end• PC members are twice as massive as their field counterparts atthe same redshift• galaxy growth was accelerated in dense environments.
PC

field (scaled)preliminary
Ito, NK+ in prep.

Rest-UV LF of PC galaxies at z~4• Significant excess at the bright end• PC members are twice as massive as their field counterparts atthe same redshift• galaxy growth was accelerated in the dense environments.

fieldPC

preliminary
Ito, NK+ in prep.

proto-BCGs (Brightest Cluster Galaxies)• 63 proto-BCG candidates• Proto-BCGs and surrounding LBGs at z~4 are redder (dustierAUV~0.7mag) than field LBGs and other cluster LBGs
• More matured (earlier galaxy formation) in proto-BCGenvironments?

Ito, NK+ 19

HI and protoclusters• Background quasars: ∼160000
BOSS quasars at z>2.2 over
10,000 deg2 (~1Gpc3)• identify overlapped multiple
Lyα forests that originatedfrom the IGM overdensity ina protocluster (Cai+16)

statistical• Subaru/HSC NB
observation to map thegalaxy (LAE) structureAsample tounveil correlation between
galaxy and IGM/CGM gas
at z>2 on a scale of>100 cMpc

HI and protoclusters
40 cMpc

Liang, NK+ in prep.

OD-OD relation• Optical Depth and Over-Density are positively correlated up to>100cMpc at z~2• galaxies are clustering in a region associated with large amount of HIgas.

preliminary
Liang, NK+ in prep.

Cross correlation between τ and galaxy• Higher τ LoSs tends to clustering around galaxies, while the lower one
is opposite at up to 4 pMpc scale• ionization or feedback from galaxies is not sufficient enough? Or cold
stream of pristine HI gas (Dekel & Birnboim 2006)?

Liang, NK+ in prep.

Quasar environment

Is AGN activity triggered by galaxy-galaxymergers?

P. Hopkins et al. (2006+)

クェーサーはどうやってできるのか？

銀河同士がぶつかってクェーサーができる→ 銀河がたくさんいるところにクェーサーは生まれやすい→ 銀河団のようなところでクェーサーは生まれる???

原始銀河団とクェーサーの関係• これまで、クェーサーの活動性は銀河衝突・銀河合体によって生じると考えられてきた。
→ 銀河団のような高密度領域でクェーサーは発現する。
• 統計的なサンプルでこの仮説を初めて検証した。

クェーサー
銀河

• 179原始銀河団中にクェーサーが存在する領域は2領域のみ。
• クェーサー位置の銀河密集度は平均値程度。
• クェーサーから一番近い原始銀河団までの距離も平均値程度。

• クェーサーは必ずしも高密度領域で発現するわけではない。
• クェーサーの発現はその環境に依存しない。

Uchiyama, NK+ 18

原始銀河団とクェーサーの関係
SDSSより4mag暗い z~4HSC quasars570個も高密度領域にはいない。
クェーサー
銀河

570個中高密度領域にいるクェーサーは4個のみ。
クェーサー位置の銀河密集度は平均値程度。
クェーサーから一番近い原始銀河団までの距離も平均値程度。
Uchiyama, NK+ in prep.

Pair quasars and protocluster• Pair quasars at z~4 with <2 Mpc separation are related to a galaxy
overdensity region with ~4.5σ (not richest)• ~20% of the z~1 pairs are within massive (> 4σ) environments.
• Quasar pairs tend to reside in overdense regions unlike single quasars.

Onoue, NK+ 18

Planck FIR detection of z~4 PCs• Stacking the images of the 179 z~4 PC candidates, the FIR emission inthe observed 12 − 850 µm wavelength range is, for the first time,
successfully detected.

Kubo, NK+ in prep.

Planck FIR detection of z~4 PCs• The observed IR SEDs of the PCs exhibit signiﬁcant excess comparedto that expected from typical star-forming galaxies .
• The z ∼ 4 PCs may host obscured AGNs missed by the selection of PCmembers in the optical.
PCDOG
QSO

LBGs (x30)

preliminary
Kubo, NK+ in prep.

QSO周囲の銀河形成阻害© Uchiyama D論SF suppression around quasars• 12 quasar regions @z=2.2-3.2• Scam/NB imagings to detectsurrounding LAEs (low-massgalaxies)• Quasar redshifts are measured
by OIII/Hβ• J21>1: Local UV background
ontensity J21 is higher thancosmic averageUchiyama, NK+ 19

SF suppression around quasars• LAEs with high Lyα EW0 of ≳ 150˚A, corresponding to low stellar mass(≲ 108M⊙), are predominantly scarce in the quasar proximity zones,suggesting that quasar photoionization eﬀects may be taking place.
• The predicted delay in star formation is about > 20 Myr, which islonger than the expected age of LAEs with EW0 of ≳ 150˚A

MUV分布

Uchiyama, NK+ 19

J21>1
J21<1

Lyα EW0分布

J21>1J21<1Galaxy CGM around quasars• The oriented Lyα images of LAEs along the projected directions
towards quasars were stacked.
• The ﬂux excess is ∼ 4× 10−19 erg s−1 cm−2 arcsec−2 with 1.5σ
signiﬁcance
near
far

Fluorescent model

Uchiyama, NK in prep.

quasar near-zone size

: neutral fraction
ሶ : quasar emissivity
𝑁𝑖𝑜𝑛𝑡𝑞 : quasar age

Willot 11

quasar near-zone size
• 10 HSC faint quasars• Accurate z measurements• Broad L range• HSC faint quasars havesystematically small Rp aspredicted.

Ishimoto, NK+ in prep.

bright quasars
faint quasars

bright quasars
faint quasars

quasar near-zone size
• Shallow redshift evolution, suggesting that NZ size is insensitive tof(HI).

Davies+19

young quasars ?

preliminary
Ishimoto, NK+ in prep.

quasar near-zone size

preliminary
Ishimoto, NK+ in prep.

Summary• galaxy environment• 179 z~4 PC candidates from 121deg2 by HSC• dark halo mass:• massive & dusty galaxies in PCs: galaxy growth wasaccelerated in dense environments.
• galaxies are clustering in a region associated with large
amount of HI gas.
• quasar environment• luminous quasars do not live in overdense regions of LBGs atz~4• The z ∼ 4 PCs may host obscured AGNs
• quasar local photoionization & fluorescent eﬀects may betaking place29• young quasars at z~6 ?