2. Overview  Presents a large sample of z=7-10 candidate galaxies  20-Z850 dropouts, 15-Y105, and 20- J125 dropouts. (55 candidates with 33 new discoveries)  Suggests a large population of low luminosity z=10 galaxies could be responsible for re-ionization

3. Re-ionization  Re-ionization occurred approx. between z=9.6-12.4.  Infrared wavelengths: z850, y105, j125, h160.  Ended around z=6 according to the Sloan Digital Sky Survey.  Task is to discover the source of energy required to ionize the neutral hydrogen.  Quasars? Early star forming galaxies?

4. Infrared wavelengths  Z850  Y105  J125  h160  Infrared light lies between the visible and microwave portions of the electromagnetic spectrum. Infrared light has a range of wavelengths, just like visible light has wavelengths that range from red light to violet. "Near infrared" light is closest in wavelength to visible light and "far infrared" is closer to the microwave region of the electromagnetic spectrum. The longer, far infrared wavelengths are about the size of a pin head and the shorter, near infrared ones are the size of cells, or are microscopic.

6. HUBBLE SPACE TELESCOPE:WIDE FIELD CAMERA 3 (Specs.)  Mercury Cadmium Telluride (MerCad) Infrared array  1024 x 1024 square pixels  Pixel size = 18 microns 2  Sensitivity ranges from 400-1700nm  FOV= 4.67 arcmin 2 (HST Handbook; Kimble et al. 2008)

7. Survey Methods  Image mosaic used was Multi Drizzle (STSDAS.DITHER)  SExtractor used two different outputs: MAG_AUTO, and MAG_ISO.

8. Z850 dropouts Z850-Y105>.08mag Horizontal line= threshold mag of 0.8 Red dots with error bars are the selected z850 drops.

9. Z=7 candidates

10. Y105 Dropouts  Candidates have a Y105-J125 magnitude greater than 0.8

11. Z=8 Candidates

12. J125 dropouts

13. Interpretation and Discussion  The careful analysis led to the largest amount of z>7 galaxy candidates.  The high quality mosaic allowed for a low S/N threshold without being severely effected by false detections.  This survey is more complete and less prone to uncertainty.

14. Conclusion  If the luminosity functions hold true beyond current detection limits, star forming galaxies could have supplied the photos required for re-ionization.  Offers a strong suggestion that JWST need be used for studying galaxies at z>8.

15. THE END