Yanchun Liang (NAOC, China) 2005-08, Lijiang

The Luminosity-Metallicityand Mass-Metallicity Relations of 0.4

Collaboration with Francois Hammer, Hector Flores, Francois Assemat at Paris-Meudon Observatory;David Elbaz, Delphine Marcillac at Saclay-Service dAstrophysique;Nicolas Gruel at Florid University;Xianzhong Zheng at MPIE;Licai Deng at NAOC;Catherine J. Cesarsky at ESO.

How much star formation was hidden by dust over the history of the universe ?(2) COBE (DIRBE) detected a diffuse background at l > 140 mm

(3) Surveys at 15,90,170,450,850mm (ISO, SCUBA) strong evolution(1) IRAS (z

ISOCAM 15 mm MIR source countsISO 15 mm source counts show strong evolutionThe comoving density of infrared light due to the luminous galaxies (LIR>1011Lsun) was more than 40 times larger at z~1 than today The main responsibility: the luminous Infrared starburst galaxies seen by ISO at z>0.4, SFRs > 50 Msunyr-1(Elbaz et al. 1999, A&A Lett., 351, L37)(Elbaz et al. 2002, A&A 384, 848; Elbaz & Cesarsky, 2003, Science, 300, 270; Flores et al. 1999, ApJ 517, 148)(4) Most of ISOCAM (>75%)galaxies are Starbursts, AGN only contribute ~20% (Elbaz et al. 2002 A&A 384 848; Fadda et al. 2002, A&A, 383, 838; Flores et al. 1999;Franceschini et al. 2003, A&A, 403, 501; Liang et al. 2003b, A&A, submitted)

(Le Floch et al. 2005, ApJ, astro-ph/0506462 )Evolution of the comoving IR energy density up to z=1 (green-filled region) and the respective contributions from low luminosity galaxies (i.e., LIR1011Lsun, orange-filled region) and ULIRGs (i.e., LIR>1012Lsun, red-filled region).

The solid line evolves as (1+z)3.9 and represents the best fit of the total IR luminosity density at 0

Spectroscopy (VLT/FORS2)follow-up

for a large sample of ISOCAM-selected sources

(Extinction, Metallicities,L-Z, Mass-Z)(Liang et al. 2004, A&A, 423, 867)

CFRS 3h, UDSR (Ultra-Deep-Survey-Rosat, Marano field),UDSF (Ultra-Deep-Survey-Firback, Marano field) (Flores et al. 2004, Elbaz et al. 2004, in preparation )1. The ISO-selected sample : 105 in 3 fields 2. The Optical Observations using VLT/FORS2 with R600 and I600spectrograph with a resolution of 5 , R=12005000 - 9000 , slit width 1.2" slit length 10"Log(LIR/Lsun)med=11.26 ( LIRGs with Log(LIR/Lsun)>11) 3. Redshift identifation4. Infrared luminosities 92 zmedian=0.587 (64 with z>0.4)5. Emission Line Galaxies (ELG) 85% EL galaxies in the ISO-detected objects , 81% EL galaxies in the total

IR luminositySimilar to Veilleux et al.1995,Kim et al. 1995:11.34 for BGSs11.38 for WGSsH0=70 km/s/MpcM=0.3, L=0.7Log(LIR/Lsun)med=11.26910111213

DeblendingExamples in UDSF

z=0.7094Log(LIR/Lsun)=11.38

Estimate dust extinctionUsing Hb/Hg ratio : A V(Balmer)Using energy balance between Hbetra and IR : A V(IR)Stellar absorption correctionJacoby et al. (1984)

Diagnostic diagram: StarburstsMost of them (>77%) are HII-region-like galaxiesConsistent with other fields:>70% of ISOCAM/15m galaxies, starbursts

Oxygen abundances in ISM12+log(O/H) = 8.35 8.93, median 8.67R23 and calibration from Kobulnicky et al. 1999Luminosity-Metallicity relation (L-Z)& Mass-Metallicity relation (Mass-Z)

L-Z relation: z> 0.4 LIRGs are metal deficient

03.0035! z> 0.4 LIRGs are 0.3 dex metal-poor from local disks (at a constant MB): ~ 50%

(12+log(O/H) = 8.35 8.93, median 8.67)! They can reach local disks locus assuming an infall time of ~ 1 Gyr(PEGASE2, Fioc and Rocca-Volmerange, 1999,astro-ph/9912179: Mtot=1011Msun ,also see Kobulnicky et al. 2003, ApJ, 599, 1006)(Liang et al. 2004, A&A, 423, 867)

Are massive spirals already formed at z~ 1 ?! Lilly et al (1998) large disk sample (rdisk > 4 h50-1 kpc) at 0.5 < z < 1: 32 (+/-13)% of them are LIRGs! Connection between LIRGs and disks (z>0.4) (HST morphologies and color maps) : 40% of LIRGs are large disks (Zheng et al, 2004, A&A) ! LIRGs have large stellar masses: 1.4 1010MO 50 Msunyr-1 , TSF(M/SFR)=0.1-1 Gyr

Time (Gyr)(Mass double time scale: 0.1-1 Gyr)

(Hammer et al. 2005,A&A,430,115)

The near-IR K-band luminosity is more directly related to the stellar mass of galaxies since it is less affected by star formation and by dust (Charlot 1998; Bell & de Jong 2000):

We compare the MK-metallicity (mass-Z) relations of these intermediate-z galaxies with those of local star-forming galaxies.

(Liang, Hammer, Flores 2005, A&A, submitted)

The 3 local sample galaxies to compare:

NFGS (Nearby Field Galaxy Survey) by Jansen et al. 2000a,bKISS ( Salzer et al. 2005)SDSS (Tremondi et al. 2004; Bell et al. 2003)

NFGS

from Jansen et al. 2000a,bSuch z> 0.4 galaxies are 0.3 dex more metal-poor from local disks (at a given MK): ~ 50%

KISS

from Salzer et al. 2005

SDSS

Tremonti et al. 2004, Bell et al. 2003;

The 7 galaxiesat z~2.3 from Shapley et al. 2004

Summary

Spectroscopy follow-up for a ISO-selected sample galaxies with 0.4