Properties of Galaxies at High- redshift in the UDS : Environmental Dependence Seong-Kook Lee, M. IM...

Properties of Galaxies at High-redshift in the UDS : Environmental

Dependence

Seong-Kook Lee,M. IM & J.-W. Kim

CEOU@SNU / Feb. 15, 2013

Motivation• Correlation among color (SF), environment and mass

Feb. 15. 2013 SSG Workshop

- at z~0, density => color : Blanton+05 mass => color : van der Wel08- at high-z (z~1), density => color : Cooper+07,Patel+09 mass => color : Cucciati+10,Grutzbauch+11

Nature vs. ?nurture

Aim : investigate dependence among galaxies’ stellar mass, environment, and stellar population properties (incl. color, SF, SFH) and its evolution up to z<2

Motivation


Aim : investigate dependence among galaxies’ stellar mass, environment, and stellar population properties (incl. color, SF, SFH) and its evolution up to z>1

• Correlation among color (SF), environment and mass

We need, (1) deep imaging data, esp. at rest-frame optical (aka. NIR), to reach z < 2 (2) panchromatic coverage from optical to MIR, for robust estimation of stellar population properties

UKIDSS (UKIRT Infrared Deep Sky Survey) / Ultra-Deep Survey (UDS)- deep NIR data from the UKIRT (J, H, & K) - wide coverage of multi-wavelength data : Optical from SUBARU (B, V, R, I’, and z’) MIR from Spitzer/IRAC- ~0.8 sq. degrees, centered at the Subaru SXDS field (J0218-05)

DATA

• Multi-wavelength Data (12 bands) - optical from Subaru/Suprimecam : B (28.4), V (27.8), R (27.7), i’ (27.7) and z’ (26.7, 3-sigma,AB) - NIR from UKIRT/WFCAM : J(24.9), H(24.2), K(24.6, 5-sigma,AB) - MIR from Spitzer/IRAC : (Ch1 – Ch4,~24,5-sigma,AB) - ~ 50,000 Objects (K-selected, z<2.2)

• Photometric Redshift - scatter Δz/(1+z)~ 0.032


Stellar Population Analysis

• SED-fitting - BC03, Chabrier IMF - delayed SFHs

(τ = 0.1 ~ 7.0 Gyr, t = 0.1 Gyr ~ tage) - 0<E(B-V)< 1.5 - Z = 0.2, 0.4, 1.0, & 2.5 Z

=> find best-fit among more than 200,000 templates


Environmental Dependence

1. Stellar Population Properties of high-z galaxies depending on the Galaxy Environment (measured by number density)

2. Candidates of high-z (proto-)Clusters and Properties of Cluster Galaxies


1. Stellar Population Properties of high-z galaxies depending on the Galaxy Environment (measured by number density)

2. Candidates of high-z (proto-)Clusters and Properties of Cluster Galaxies

1. Galaxy Properties @ different Environment

• Method 1. Count galaxies within distance < 500/h kpc, and at Δz < 0.032*(1+z) => N_gal 2. To estimate background, calculate N_gal for all galaxies within redshift bin => find mean (N_0) and SD (sigma_N) 3. Define over-(under-)density measure as (N_gal – N_0)/(sigma_N)



• Results : Colour - Density



• Results : Colour – Stellar Mass


2. (proto-) Cluster Candidates @ High Redshifts

• Method 1. Galaxy counts at each grid point in RA-Dec space (Δ = 12”) within r < 500/h kpc, at each redshift bin (Δz = 0.02) 2. Find large structures of connected bins (> 10 bins) with galaxy counts > 4-sigma



• Method : continued 3. Connect the structure found in successive redshift bins (> 3-bins) and find central position and redshift for each (proto-) cluster candidates 4. Find galaxies belonging to each (proto-)cluster (within r < 700/h kpc, Δz/(1+z) < 0.032)



• Results - found 38 candidates within 0.5 < z < 2.0 - recovers 14 (proto-)clusters published (van Breukelen+06,Finoguenov+10,Papovich+10)



• Results: sSFR dist. (cluster vs. field)


Summary

• Using Deep NIR imaging data from the UKIRT & panchromatic photometric data,

• We are investigating stellar population properties of high-redshift galaxies depending on the environment

• And, searching galaxy (proto-)cluster candidates at high redshifts, and studying their evolutionary properties.


Please stay tuned !!Please stay tuned !!

Properties of Galaxies at High- redshift in the UDS : Environmental Dependence Seong-Kook Lee, M. IM...

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