The Spectral Energy Distribution of LAEs at 2< z <3.1

1. October 7th, 2008 The Spectral Energy Distribution of LAEs at 2<z<3.1 Lucia Guaita (P.U. Catolica) PhD advisors: Eric Gawiser (Rutgers), Nelson Padilla (P.U. Catolica) Collaborators: CarylGronwall, Robin Ciardullo (Penn State) , Harold Francke (U. Chile), Nick Bond (Rutgers)

2. Outline LAEs detection and their relation with LBGs at z = 3 Fit of the SED (physical nature) Clustering analysis (connect galaxies at different redshifts) Photometric 2-color method to select different redshift galaxies (predict) How all this process can be applied for new (or future) survey of detection of Lyman alpha line galaxies photometric properties SED properties

3. Sample of 160 LAEs in ECDF-S BV-NB5000 > 1.03 EWobs > 80 Å, emission line flux > 1.5x10 -17 erg/sec cm 2 Gronwall et al. 2007 At z=3 LAEs occupy the same 2-color diagram region of LBGs, but they are fainter in their continuum (R=27) Color similarities , SED (physical nature) spectroscopicallyconfirmed without spectroscopy spectroscopy but not redshift Vcorr = NB contribution is subtracted from V band + polygon = LBG selection region curve = track of an LBG template spectrum (Shapley et al 2003)

4. Shapley et al 2001, z=3LBGs, R<25.5: fit LBG spectra with SED model young: age < 35 Myr, E(B-V)=0.26, SFR=210/h2 M/yr, M=2.9 109/h2 M old: age > 1 Gyr, E(B-V)=0.1, SFR= 25/h2 M/yr, M=4.0 1010/h2 M median: age = 320 Myr, E(B-V)=0.155, SFR= 45/h2 M/yr, M=1.2 1010/h2 M Sample of 160 LAEs in ECDF-S BV-NB5000 > 1.03 EWobs > 80 Å, emission line flux > 1.5x10 -17 erg/sec cm 2 • 30% of z=3 LAE sample are detected in the 3.6 μm IRAC band (m3.6AB > 25.2): • high-mass end of the LAE mass function, stellar mass > 3x109 M • 70% of z=3 LAE sample are undetected by IRAC •  • SED of typical LAE •  • average flux in MUSYC UBVRIzJK+[3.6,4.5,5.6,8.0 μm] • from the stack of the 70 % IRAC-undetected objects •  • LAEs typical SED fit • Two-burst scenario with the old component as an instantaneous burst • and the young component as an exponentially declining starburst • Maraston (2005) population synthesis model

5. 20 Myryoungpopulation almost constant SFR, no dust specific SFR = 4 10 -9 /yr 2 Gyrold population as an instantaneous early burst typical LAEs are in their early (dust-free) phase of starburst Gawiser et al 2007 Sum of the young and old components Only the young component fit Only the old component fit consistent with 200 Myr population (Lai et al 2008)

6. Spectroscopy of this sample to confirm LAEs candidates and for clustering analysis LAEs at z=3.1 evolve into ~L* galaxies at z=0 this group work Gawiser et al 2007 “Harold Francke’s poster” dashed tracks= median of conditional mass function

7. Extrapolating the behavior at redshift 3.1 we expect similarities between LAEs and star forming galaxies at 2 < z < 2.7 (Steidel’s BX sample) SED fit parameters to simulate magnitudes and colors of star forming galaxies at 2 < z <≈ 3 as LAEs faint in continuum E(B-V)=0,~20 Myr-------- E(B-V)=0.26, 35 Myr E(B-V)=0.155, 320 Myr E(B-V)=0.1, 1Gyr E(B-V)= 0.3, 2Gyr

8. 36 hours with [OII] filter MOSAIC II instrument at CTIO Lyα (1215.67 Å)         ~ 3700 Å z~2.1 ECDF-S 3-13 December 2007 5σ point source detection depth of 24.8 in NB3727 Å, to obtain the same luminosity of NB4990 Å • following the same process • traced for LAEs at z=3.1 •  • [OII] NB excess in magnitude • respect U38, U and B broad bands • (MUSYC broad band data) U,U38,B WFI@LaSilla broad bands OII MOSAIC II@CTIO narrow band Typical Lyman alpha line spectra

9. From 8 nights CTIO 16 mosaics frames • final stacked image of 18 + 18 hours: • (sky subtracted, aligned, trimmed, • normalized, photometric calibrated) • SExtractor program to extract sources in double-image mode • to optimize source extraction and build the [OII] catalog • SExtractor to the negative image to estimate false detections • criterion to select LAEs candidates • in narrow band vs broad band (combination of U and B bands) ECDF-S 1.4” seeing [OII] image

10. real and false detections: flux_aper/fluxerr_aper (1.4 “ aperture diameter) by matching MUSYC broad bands photometric catalog with NB data : (UB-o2) color cut R>16 to avoid bright stars from OII frame

11. Color cut  density of LAEs candidates at z~ 2 ‘match’ with the broad band data  stacked fluxes and SED best fit parameters we need spectroscopy: to confirm candidates for clustering analysis  evolution from z=2 to z=0 to test 2-color diagram selection criterion  detect LAEs in a larger and more reliable sample than with just a cut in EW limit by differentiating LAEs at lower EW from low redshift interlopers We’ll compare the photometric, spectroscopic and SED fit properties of LAEs at z=2 to those of LAEs at z=3 and other SF galaxies at the same range of redshift Good agreement with LBG selection region It needs more confirmation at z~ 2 all the data in the catalog theoretical criteria spectroscopic follow-ups from MUSYC-GOODS spectroscopic catalog

12. Conclusions: LAEs at z=3.1 20 Myryoungpopulation almost constant SFR, no dust high specific SFR LBG selection region typical LAE are in their early (dust-free) phase of starburst LAEs occupy the same 2-color diagram region of LBGs • LAEs properties at 2<z<3.1 LAEs are progenitors of ~ L* galaxies LAEs at z=2