clustering properties of infrared bright dust-obscured...

The 6th Subaru International Conference 2016.11.29

Toba et al. 2016 re-submitted

Clustering properties of infrared bright dust-obscured galaxies selected with HSC and WISE

Yoshiki TOBA (ASIAA)

Tohru Nagao, Masaru Kajisawa, Taira Oogi, Masayuki Akiyama, Hiroyuki Ikeda, Jean Coupon, Michael A. Strauss, Wei-Hao Wang, Masayuki Tanaka, Mana Niida,

Masatoshi Imanishi, Chien-Hsiu Lee, Hideo Matsuhara, Yoshiki Matsuoka, Masafusa Onoue, Yuichi Terashima, Yoshihiro Ueda, Yuichi Harikane, Yutaka

Komiyama, Satoshi Miyazaki, Akatoki Noboriguchi, Tomonori Usuda

Introduction

What are Dust-Obscured Galaxies (DOGs)?

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Dust-Obscured GalaxiesIntroductionClustering properties of DOGs

R - [24] ≥ 7.5 (AB mag)

~ ULIRGs

• An optically faint but IR bright objects.

• Most DOGs are u l t ra-luminous infrared galaxies (ULIRGs: LIR ≥ 1012 Lsun).

flux (24 µm) [mJy]1 100.1

8

654

7

9

R -

[24

] (A

B m

ag)

Calanog+13

DOGs criterion

z = 1.99 ± 0.45

Dey+08

z ~ 2

• Confirmed from follow-up observations (NIR and MIR spectroscopy).

3

Bump DOGs

PL DOGs

Two types of DOGsIntroduction

Power-Law (PL) DOGs

• They show a rising power-law SED, which indicates an AGN activity.

AGN-dominated DOGs

Bump DOGs

• They show a rest-frame 1.6 µm “bump” in their SEDs.

• They also show strong PAH emission.,which indicates a SF activity.

SF-dominated DOGs

Dey+084

Clustering properties of DOGs

IR-faint DOGs vs. IR-bright DOGsIntroduction

5

Dey+08

flux (24 µm) [mJy]0.4 0.6 0.8 1.0P

L D

OG

s fr

acti

on

[%]

80

60

40

20

0

100IR-bright DOGs

100

10

1.0 0.60.8flux (24 µm) [mJy]

0.4

Num

ber

/deg

2

Dey+08

• The fraction of PL DOGs (i.e., A G N - d o m i n a t e d D O G s ) increases with increasing MIR flux.

• IR-bright DOGs are expected to be AGN dominated DOGs.

• The number densities of DOGs decreases with increasing MIR flux., which means IR-bright DOGs are very rare.

• It requires a large area survey.

IR-faint DOGs


Clustering of DOGsIntroduction

6


Clustering of DOGsIntroduction

6


The clustering properties of IR-bright DOG are still unclear

Introduction

7

IR-faint (SF)・IR-bright (AGN)

IR-bright, optically faint obj. z~2

Strongly clustered population


What are the DOGs

Introduction

7

IR-faint (SF)・IR-bright (AGN)

IR-bright, optically faint obj. z~2

Strongly clustered population


What are the DOGs

Investigating the clustering property of IR-bright DOGs

=> Comparing it with that of IR-faint DOGs and other populations (e.g., SMGs, quasars)

Purpose of this work

Data and Analysis

How do we discover IR bright DOGs?

8

Dataset used for DOGs surveyData and Analysis

9


DOGsOptically-faint and IR-bright objects

HSC-SSPS15B

wide layer dataALLWISE

Uniqueness of our DOGs surveyData and Analysis

10


HSC+WISE(Final status)

COSMOS

SWIRE (XMM/Chandra)

NDWFS

CDF/E-CDFS/EGS

E-CDFS

GOODS-N

GOODS-S

This study (Toba+15)Toba+15(S14A_0)

Toba+16(S15B)

Sample SelectionData and Analysis

11

!"#$"%&'$()*+,-.(/+*0,*1..2//3-)+2%4%564778459:

;,01/!"#?@>2/A0/B2.B-C,02=$8$DEF$

$2/1/-1.,*.1

12

!"#$"%&'$()*+,-.(/+*0,*1..2//3-)+2%4%564778459:

;,01/!"#?@>2/A0/B2.B-C,02=$8$DEF$

$2/1/-1.,*.1

13

!"#$"%&'$()*+,-.(/+*0,*1..2//3-)+2%4%564778459:

;,01/!"#?@>2/A0/B2.B-C,02=$8$DEF$

$2/1/-1.,*.1

Results

14

• Auto-correlation function• Correlation amplitude as a function of redshift

Auto Correlation Function of DOGs

15

β = 0.9 (IR-faint DOGs: Brodwin+08)

ACF: ω(θ) = Aω θ-β

Clustering properties of IR-brightDOGs Results

Data are well-fit by ω(θ) = Aω θ -0.9

Aω as a function of MIR flux

16

Clustering properties of IR-brightDOGs Results

IR-faint IR-bright

IR-faint DOGs (Brodwin et al. 2008)

IR-bright DOGs (this work)

Cor

rela

tion

amp

litud

e

Flux-dependent clustering of DOGs

Discussions

17

• Redshift Distribution of IR-bright DOGs• Bias factor

Correlation length and biasDiscussions

18

Given the ACF and N (z) in assumed cosmology, we can calculate the real-space correlation length (r0)


From the real-space correlation function (ξ), we define the DOG clustering bias (bDOG) at 8 h−1 Mpc

Redshift Distribution

19

Case 1

Case 2

N(z) = 1.99 ± 0.45

Dey+08

N(z) = 1.19 ± 0.30

Toba+16

Nz (IR-faint DOGs)‖

Nz (IR-bright DOGs)

Photo-z from MIZUKI (Tanaka+15)

N (z) = 1.99 ± 0.45

N (z) = 1.19 ± 0.30

Discussions

245/1141(~17%)

MIZUKI code (Tanaka 2015)

Observed wavelength [Å] Observed wavelength [Å]

Clustering properties of IR-brightDOGs

Redshift Distribution

19

Case 1

Case 2

Nz (IR-faint DOGs)‖

Nz (IR-bright DOGs)

Photo-z from MIZUKI (Tanaka+15)

N (z) = 1.99 ± 0.45

N (z) = 1.19 ± 0.30

Discussions

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!"#"$

%#&%

Clustering properties of IR-brightDOGs

Bias and Dark matter halo mass

20

Clustering properties of IR-brightDOGs Discussions

13.013.0

IR-faint DOGs (Brodwin et al. 2008)

SMGs (Hickox et al. 2012)

SDSS quasars (Shen et al. 2009)SDSS quasars (Ross et al. 2009)

WISE selected red AGNs (Donoso et al. 2014)ULIRGs (Farrah et al. 2006)24 µm selected galaxies (Magliocchetti et al. 2008)

IR-bright DOGs (Case 1)IR-bright DOGs (Case 2)

14.0

13.5

13.0

12.5

12.0

Weakclustering

Strong clustering

IR-bright DOGs reside in the massivedark matter halo with a mass of

log [MDMH/(h-1M◉)] ~13.6

SummarySummary

1. We newly discovered 4367 IR-bright DOGs based on the HSC-SSP and WISE data.

2. The correlation amplitude of DOGs increases with increasing MIR flux.

3. IR-bright DOGs are strongly clustered and they could reside the massive dark matter halo with a mass of log [M/(h-1M◉)] ~ 13.6.

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The 6th Subaru International Conference

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clustering properties of infrared bright dust-obscured...

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