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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, 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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  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

  2. OUTLINE Sample refinement Photometric studies Morphological analyses Conclusions

  3. 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)

  4. 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

  5. SED fitting 48 sources with z_sp; Re-estimates of z_p are good

  6. Examples: 2 with/without spectral 2 with/without 24MIPS

  7. 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

  8. 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

  9. SFRs • 4 -- 220 M⊙ yr -1 • Median • ~ 30 M⊙ yr -1

  10. Stellar masses 2.3 x 10 8 --- 7.7 x 1011 M⊙ median ~ 10 10 M⊙

  11. SFR vs M * SF sequence EST– Irr – SB , more distant to the main sequence Main sequence

  12. Least square sSFR vs M * “downsizing” SB– Irr – EST , more significant NUV =26.2

  13. U-Bvs M * “blue cloud” suggest evolution from SB – Irr – EST along the blue cloud Faber et al. 07

  14. 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

  15. Visual Classifications 10“spiral” LBGs which have two prominent components

  16. Visual Morphologies 8 “string” LBGs

  17. Visual Morphologies 40“interacting”/ 20 “companion” LBGs

  18. Visual Morphologies 191“compact”/ 5“ low surface brightness” LBGs

  19. 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

  20. 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

  21. 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

  22. Correlations SFR vs sersic indexes and sizes more compact, higher SFR

  23. M *vs sersic indexes and sizes bigger LBGs, more massive in M*; central stellar surface density shows a small dynamic range;

  24. 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

  25. Thanks

  26. 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

  27. 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

  28. 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

  29. COMBO-17 –MUSYC cross-identification

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