Photometric and morphological properties of lbgs at z 1
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Photometric and Morphological Properties of LBGs at z~1. Chenggang Shu Key Lab for Astrophysics, Shanghai Normal University (ShNU) with Zhu Chen (ShNU), Denis Burgarella, V eronique B uat (OAMP), Jiasheng Huang (CfA) & Zhijian Luo (ShNU).

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Photometric and Morphological Properties of LBGs at z~1

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Photometric and morphological properties of lbgs at z 1

Photometric and Morphological Properties of LBGs at z~1

Chenggang Shu

Key Lab for Astrophysics,

Shanghai Normal University (ShNU)

with Zhu Chen (ShNU), Denis Burgarella, Veronique Buat (OAMP),

Jiasheng Huang (CfA) & Zhijian Luo (ShNU)

The 9th Sino-German Workshop on Galaxy Formation and Cosmology , Hangzhou, China


Outline

OUTLINE

Sample refinement

Photometric studies

Morphological analyses

Conclusions


Photometric and morphological properties of lbgs at z 1

1. Sample Refinement

  • 420 UV selected LBGs candidates (0.9<z<1.3), (Burgarella et al. 07) by FUV-NUV >2, NUV<26.2

  • GALEX observation, E-CDF-S

    FUV: λ=1516AÅ (~765AÅ at z~1)

    NUV: λ=2267AÅ(~1155AÅ at z~1)


Photometric and morphological properties of lbgs at z 1

z_p

  • photo-z from COMBO-17, (Wolf et al. 04);

  • 394 sources in MUSYC catalog (Cardamone et al. 06)

Significant differences in z_p

Re-estimating by SED fitting

394 MUSYC sources

FUV + NUV + UBVRI + zJHK + IRAC

15 bands + MIPS24

26 COMBO-17 sources

FUV+NUV+UBVRI

7 Bands + MIPS24


Photometric and morphological properties of lbgs at z 1

SED fitting

48 sources with z_sp;

Re-estimates of z_p are good


Photometric and morphological properties of lbgs at z 1

Examples:

2 with/without spectral

2 with/without 24MIPS


Photometric and morphological properties of lbgs at z 1

LBGs at z~1

379 LBGs are selected with 0.7 < z_p < 1.4;

90% of the preliminary candidates

Solid: re-estimates

Dashed: C - 17

Dotted: MUSYC


Photometric and morphological properties of lbgs at z 1

2. Photometric Properties

SpT types

  • 258 starburst (BC03)

  • 5 Arp220

  • irregular (CWW)

  • 1 irregular (BC03)

  • 10 Scd (CWW)

  • 1 Sbc (CWW)

  • 1 E (BC03)

  • 1 E (CWW)

Starbusrt

Arp200

SB

Irr

Irregular

Scd

Sbc

E

EST


Photometric and morphological properties of lbgs at z 1

  • SFRs

  • 4 -- 220 M⊙ yr -1

  • Median

  • ~ 30 M⊙ yr -1


Photometric and morphological properties of lbgs at z 1

Stellar masses

2.3 x 10 8 ---

7.7 x 1011 M⊙

median

~ 10 10 M⊙


Photometric and morphological properties of lbgs at z 1

SFR vs M *

SF sequence

EST– Irr – SB ,

more distant to

the main sequence

Main

sequence


Photometric and morphological properties of lbgs at z 1

Least square

sSFR vs M *

“downsizing”

SB– Irr – EST ,

more significant

NUV =26.2


Photometric and morphological properties of lbgs at z 1

U-Bvs M *

“blue cloud”

suggest evolution

from SB – Irr – EST

along the blue cloud

Faber et al. 07


Photometric and morphological properties of lbgs at z 1

3、Morphological analyses

GEMS two-band imaging.

ACS/WFC

Resolution: 0.03”/pixel

(1” ~ 8kpc for z~1)

mAB(F606W) = 28.3

mAB(F850LP) = 27.1

(Rix et al. 2004)

z = F850LP

V = F606W

It covers ~90% area of

E-CDF-S field

326 of 379

LBGs (~90%) in this field

275 detected in both bands

GOODS imaging


Photometric and morphological properties of lbgs at z 1

Visual Classifications

10“spiral” LBGs

which have two

prominent

components


Photometric and morphological properties of lbgs at z 1

Visual Morphologies

8 “string” LBGs


Photometric and morphological properties of lbgs at z 1

Visual Morphologies

40“interacting”/ 20 “companion” LBGs


Photometric and morphological properties of lbgs at z 1

Visual Morphologies

191“compact”/ 5“ low surface brightness”

LBGs


Structure decomposition

Structure decomposition

  • GALFIT, a two-dimensional fitting algorithm of galaxy images written by (Chien Y.Peng et al. 2002).

  • Originally designed to modeling light profiles of spatially well-resolved, nearby galaxies observed with HST

  • PSF: Tinytim software

  • 251 sources can get reasonable fitting results


Photometric and morphological properties of lbgs at z 1

An Example

F606W

F850LP

observation

modelling

residual

Sérsic reff (kpc) a/b chi2

F606W: 0.52 0.425 0.99 0.873

F850LP: 0.94 0.533 0.99 0.823


Photometric and morphological properties of lbgs at z 1

Distributions of sersic indexes and sizes

Dominated by late type galaxies

Meadian sizes: ~ 2.22kpc in v and 2.76kpc in z

hatched: v

empty: z


Photometric and morphological properties of lbgs at z 1

Correlations

SFR vs sersic indexes and sizes

more compact, higher SFR


Photometric and morphological properties of lbgs at z 1

M *vs sersic indexes and sizes

bigger LBGs, more massive in M*;

central stellar surface density shows a small dynamic range;


Photometric and morphological properties of lbgs at z 1

An LBG sample at 0.7 < zp<1.4 is refined based on Burgarella et al. (07)

Most of the LBGs are starburst galaxies;

LBGs locate in the region of star forming sequence. The “downsizing” effect is clearly found and the effect is more significant for LBGs from the SB, Irr and EST groups;

LBGs distribute in the “blue” cloud. We suggest that star forming galaxies, evolve from later to earlier types in the blue “cloud”;

LBGs at z~1 are dominated by disklike galaxies;

LBGs in our sample display significant size-stellar masses relations, more massive galaxies, larger sizes;

More compact LBGs have more active star formation activities.

4、Conclusions


Photometric and morphological properties of lbgs at z 1

Thanks


Optical counterparts cross identification

Cross-identification is done within the radius of 2’’ centered on the coordinates of indivdual LBG candidates

379 LBG candidates with only one counterparts

40 LBG candidates with two counterparts

1 LBG candidates with 4 counterparts

Optical counterparts cross-identification


Sample refinement

Sample refinement

1 single counterparts—exactly their corresponding counterparts

2 pair and four counterparts

Re-estimate photo-z

One 0.9<z<1.3

None 0.9<z<1.3

Two 0.9<z<1.3

Real LBG

Small chi square per degree


Combo 17 and musyc catalog

COMBO-17 (Wolf et al. 04)

ECDF-S, more than 30’by 30’, R<26

17 –band filter set covering the range 350-930nm

25000 galaxies with redshift errors of dz/(1+z) ~ 0.049

MUSYC (Gawizer et al. 06)

ECDFS, ~30’by 30’, R<25.3

32 band photometric catalog,

Covering the range 360nm-8micron

with redshift errors of dz/(1+z) ~ 0.02

COMBO-17 and MUSYC catalog


Combo 17 musyc cross identification

COMBO-17 –MUSYC cross-identification


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