第４回銀河進化研究会 (2017/6/9, 大阪大学)

The nature of Ha-selected galaxies
along the huge cosmic web at z=0.4
revealed by HSC-SSP survey
Koyama et al. 2017, submitted to PASJ special issue, arXiv:1704.05979

Yusei Koyama (Subaru), Masao Hayashi (NAOJ), Masayuki Tanaka (NAOJ),
Tadayuki Kodama (Tohoku), Rhythm Shimakawa (UC Santa Cruz),
Moegi Yamamoto (GUAS), Fumiaki Nakata (Subaru), Ichi Tanaka (Subaru),
Tomoko Suzuki (NAOJ), Ken-ichi Tadaki (NAOJ), Atsushi Nishizawa (Nagoya),
Kiyoto Yabe (IPMU), Yoshiki Toba (ASIAA), Lihwai Lin (ASIAA),
Hung-Yu Jian (ASIAA), Yutaka Komiyama (NAOJ)

Galaxy evolution & environment“ Morphology–Density Relation”

SpiralS0E

red, old,
low SF activity

blue, young,high SF activity

Low-density

High-density(Dressler 1980)

log SFR [M¤/yr]

Environmental independence of theSF main sequence at z=0

low-density

high-density

(z=0)

(z=0)
log M★

From SDSS SF galaxies by Peng+2010, see high-z result by Koyama+2013

Red (dusty) SF galaxies: a key population
for understanding environmental effects?
z’NB921

Ha@z=0.4
Rc<0.5 Mpc

0.5<Rc<1.0 Mpc

1.0<Rc<1.5 Mpc

West ClumpGroups■: red HAE (B-I>2)□: blue HAEs (B-I<2)

Narrow-band Ha survey of A851 cluster (z=0.4)
with Subaru/Suprime-Cam by Koyama et al. (2011).

HSC-SSP for environment study• HSC-SSP survey overview paper (Takada+, arXiv:1704.05858)• HSC-SSP data release (DR1) paper (Tanaka+, arXiv:1702.08449)

NB emitter catalog
from HSC-D &HSC-UD data byHayashi et al. (2017)arXiv:1704.05978• ~8,100 Ha emitters• ~8,700 [OIII] emitters• ~16,900 [OII] emitters
The catalogs will be made public
after the paper is acceptedThis study: a case study in DEEP2-3 field• grizy + NB921 (~5-deg2)• NB921 < 23.5 mag (AB)• Ha emitters (HAEs) at z=0.40– NB excess– Spec-z / Photo-z / Color• All “member” galaxies at z~0.4– Galaxies with 0.35<z(phot)<0.45– HAEs (regardless of photo-z)Huge cosmic web hosting twin clusters at z=0.4
traced by N921-selected Ha emitters in DEEP2-3

Huge cosmic web hosting twin clusters at z=0.4
traced by N921-selected Ha emitters in DEEP2-3
CAMIRAclusters at z~0.4(Oguri+2017)

Huge cosmic web hosting twin clusters at z=0.4
traced by N921-selected Ha emitters in DEEP2-3
CAMIRAclusters at z~0.4(Oguri+2017)

zcl=0.4067

Color-density relation for all galaxies
M★ estimate with Y-band
photometry + M/Lcorrection with g-i colorAll

Fixed M★
Density measuredwith 5th nearest
neighbor approach.

: Median: 25%/75%

As expected, galaxies in higher-density
environment tend to be redder.

Color-density relation for HAEs
All HAEs: Median: 25%/75%

HAEs at fixed M★

There still remains color-density correlationfor HAEs, driven by massive HAEs in highestdensity environment.

Color-density relation for HAEs
All HAEs: Median: 25%/75%

M★ vs density for HAEs
HAEs at fixed M★

There still remains color-density correlationfor HAEs, driven by massive HAEs in highestdensity environment.

SFR(Ha) vs. density for HAEs
All HAEs: Median: 25%/75%[NII] correction with
Sobral+2012 method. Dust
extinction correction with
Koyama+2015 recipe using
M* + EW(Ha) approach.

HAEs at fixed M★

Mild increase of SFR toward high-density
environment, again driven by massive
HAEs in high-density environment.

sSFR(Ha) vs. density for HAEs
All HAEs: Median: 25%/75%

HAEs at fixed M★

No significant environmental dependence
of sSFR at fixed M★, consistent withenvironmental independence of SFMS.

Discussion 1:“Global” vs. “Local” environment
銀河数密度

HAE only

赤ほどM★大• Both “Global” and“Local” environment
play an important role
to change the natureof galaxies.
• Need furtherinvestigation with full
HSC-SSP data (andPFS in future)銀河団からの距離

Discussion 2:

Color vs density for HAE-HAE pair
• NB imaging data has
advantage in finding SF
galaxy pairs.
• Redder colors of HAE
pairs in high-density
environment?
• Again, interesting to do
further investigation
with full HSC-SSP dataSummary• Discovery of large-scale structure hosting twin
clusters at z=0.4, traced by Ha emitters inDEEP2-3 field with HSC-Deep data.
• Ha emitters in higher-density environments tend
to have redder colors, higher M*, and higher SFR.
• Median (s)SFR of Ha-selected galaxies is
independent of environment at fixed M*.
• Colors of HAE-HAE pairs might be affected by
global environment – need further investigation
with full HSC data (+ PFS in future).