The LALA Survey

1. The LALA Survey Rhoads et al. 2000

2. The LALA Survey Rhoads et al. 2000

3. The LALA Survey Rhoads et al. 2000

4. Subaru and Supreme Taniguchi et al. 2004

5. Subaru and Supreme Taniguchi et al. 2004

6. Blind spectroscopy searches • Martin et al. 2006: ultra-sensitive spectroscopic survey of Lya emitters at z~5.7 • Multi-slit windows technique complements other emission-line surveys. • Narrow-band imaging surveys cover large areas of sky but only detect much brighter objects. Long-slit spectra taken along cluster caustics yield intrinsically fainter lensed Lya emitters but probe small volumes of space. • To a line flux limit of a few times 10^-18 erg/s/cm^2, we found 150 emission-line sources with no detectable continuum. • These candidates are being re-observed with broad spectral coverage to determine the line identity. To date, the interloper to Lya ratio is about 8:1. • The sky positions of the Lya candidates generally do not coincide with those of foreground objects in ultra-deep r band or i' images -- consistent with the presence of a strong Lyman break.

7. Blind spectroscopy searches

8. Blind spectroscopy searches

9. Lya survey to constraints reionization Malhotra et al. 2006 The observed number density of Lya sources at z~6.5 implies a minimum volume of the intergalactic medium that must be ionized, in order to allow the Lya photons to escape attenuation. Volume estimated by assigning to each Lya emitter the minimum ionized bubble that would allow half its Lya photons to escape. This implies a lower limit to the ionized gas volume fraction of 20%-50% at z=6.5. This limit is completely independent of what ionizing photon sources produced the bubbles. Deeper Lya surveys are possible with present technology and can strengthen these limits by detecting a higher density of Lya galaxies.

10. Lya Surveys: Implications for Galaxy Formation Dawson et al. 2004 Keck low resolution optical spectra of 17 Lya galaxies and one Lyman break galaxy at z~4.5 discovered in the Large Area Lyman Alpha survey (LALA). Sample of ~350 candidate Lya galaxies at z~4.5 in a search volume of 1.5×106 comoving Mpc3. Targeted 25 candidates for spectroscopy; the 18 confirmations suggest a selection reliability of 72%. The large rest equivalent widths (median Wl~80 Å) but narrow physical widths (Deltav<500 km s-1) of the Lya emission lines, and the lack of accompanying high-ionization emission lines, suggest that these galaxies are young systems powered by star formation rather than by AGN. Theoretical models of galaxy formation suggest that a small fraction of Lya galaxies at z~4.5 may still be nascent, metal-free objects. Indeed, we find with 90% confidence that three to five of the confirmed sources show Wl>240 Å, exceeding the maximum predicted for normal stellar populations. Nonetheless, we find no evidence for HeII l1640 emission in either individual or composite spectra, indicating that although these galaxies are young, they are not truly primitive, Population III objects.

11. Lya Surveys: z~7

12. Lya Surveys: z~7

13. Lya Surveys: z~7

14. Galaxies at z~9? Willis & Courbin 2005

15. Lya Surveys: Searching for First Light Near-IR search for galaxies At z=9.17 Mannucci et al. 2006

16. Lya Surveys: Searching for First Light Mannucci et al.

17. Emission Line SurveysLecture 4 Mauro Giavalisco Space Telescope Science Institute University of Massachusetts, Amherst1 1From January 2007

18. Lya searches to complement continuum ones Steidel et al. 1999

19. Unattenuated Spectrum Spectrum Attenuated by IGM B435 V606 z850 Finding high-redshift galaxies:colorselection B435V606i775z850 • Color selection is very efficient in finding galaxies with specific spectral types in a pre-assigned redshift range • Wide variety of methods available, targeting a range of redshifts, galaxies’ SEDs: • Lyman and Balmer break (Steidel, Adelberger, MG) • DRG (Franx, Labbe et al.) • BzK (Daddi et al.) • Photo-z (Mobasher et al) • Here, the case of • “Lyman-break galaxies” • GOODS yielded the deepest and largest quality samples of LBGs at z~4 to ~6 (7?) z~4

20. Colorselection at z>3B-band dropouts: 3.5<z<4.5 Vanzella et al. 2006

21. Colorselection at z>3 V-band dropouts: 4.5<z<5.5

22. Colorselection at z>3i-band dropouts: 5.5<z<6.5

23. Colorselection at z>3z-band dropouts: 6.5<z<7.5

24. The Redshift Distribution #183 LBGs at z>3 are targets of the ongoing GOODS spectroscopic time with the ESO VLT and Keck Vanzella et al. 2005, 2006 in prep. Stern et al. 2006 in prep. Giavalisco et al. 2004; 2006, in prep. #27

25. Lya searches to complement continuum ones Steidel et al. 1999

26. Lya searches to complement continuum ones Steidel et al. 1999 At faint end of LF, Lya emitters might dominate the LF SFD underestimated by as much as 2x Other important works by: Hu et al. 2001 Ouchi et al. 2004 Taniguchi et al. 2004

27. Lya searches to complement continuum ones Results from the GOODS survey (Giavalisco et al. 2004) Vanzella et al. 2006

28. Lya searches to complement continuum ones Vanzella et al. 2006

29. Lya searches to complement continuum ones Vanzella et al. 2006

30. Lya searches to complement continuum ones Vanzella et al. 2006

31. Lya searches to complement continuum ones Vanzella et al. 2006

32. Lya searches to complement continuum ones Vanzella et al. 2006

33. Lya searches to complement continuum ones Vanzella et al. 2006

34. What is causing the difference in the spectra? “Absorbers” tend to be redder than emitter. However, there are blue “absorbers”, too. No strong correlation of spectral “types” with the ellipticity of the galaxies. Are these disks? Possibly an effect of geometry of gas and dust, metallicity and age (see Shapley et al. 2004). Abs. Em.

35. Colorselection at z~2: BzK galaxies BzK selection: 1.4<z<2.5 • BzK selection well suited for 24mm MIPS studies: • Selected range 1.4 < z < 2.5 places strong mid-IR features in 24mm band • Color selection includes objects with red UV continuum, e.g., from extinction • K-band selection suitable for relatively massive galaxies (Daddi et al. 2005)