Download Infrared light

Overview
 Presents a large sample of z=7-10
candidate galaxies
 20-Z850 dropouts, 15-Y105, and 20J125 dropouts. (55 candidates with
33 new discoveries)
 Suggests a large population of low
luminosity z=10 galaxies could be
responsible for re-ionization
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?
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.
HUBBLE SPACE TELESCOPE:WIDE
FIELD CAMERA 3 (Specs.)
 Mercury Cadmium Telluride (MerCad)
Infrared array
 1024 x 1024 square pixels
 Pixel size = 18 microns2
 Sensitivity ranges from 400-1700nm
 FOV= 4.67 arcmin2
(HST Handbook; Kimble et al. 2008)
Survey Methods
 Image mosaic used was Multi Drizzle
(STSDAS.DITHER)
 SExtractor used two different
outputs: MAG_AUTO, and MAG_ISO.
Z850 dropouts
Z850-Y105>.08mag
Horizontal line=
threshold mag of
0.8
Red dots with error
bars are the
selected z850
drops.
Z=7 candidates
Y105 Dropouts
 Candidates have a
Y105-J125
magnitude greater
than 0.8
Z=8 Candidates
J125 dropouts
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.
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.
THE END