1. Possibility of UV observation in Antarctica
04/25/08
Hirofumi Okita(M1)

2. UV Observation UV ・・・10～400nm (Lymanα=121.6nm)
　But, it is impossible to observe, because the Ozone Layer absorbs UV.
In Antarctica, unfortunately, the Ozone Hole exists.
→ Possibility of UV observation in Antarctica
I examined the paper of GALEX (Galaxy Evolution Explorer).

3. GALEX Launch on 2003, 50cm space telescope Imaging / spectroscopy
FUV (135～178nm) (resolution 4.3arcsec / 0.8nm)
NUV (177～273nm) 　(5.3arcsec / 2nm)
GALEX (UV astronomy )Science
・SFR (Star Formation Rate)
・UV Survey
・Supernova, comet, variable star, massive star, interstellar matter, etc…

4. Jean-Michel Deharveng et al.
Lyman α emitting galaxies at 0.2 < z <0.35 for GALEX spectroscopy
Jean-Michel Deharveng et al.
astro-ph 14 Mar 2008 accepted
arXiv:

5. introduction ・Lyα photon are scattered by neutral hydrogen.
・Lyα emission remains the only mean for identifying galaxies at high redshifts.
・Density evolution of Lyα emitters trace the history of the cosmic re-ionization.
See the near galaxies…
(1)Whether the Lyα escape is related to specific properties of galaxies
(2)Whether the Lyα emission evolves from current epoch to high z as the cosmic star formation rate traced by Balmer lines or the UV continuum of galaxies

6. ・Properties of the Lyα emitting galaxies ・The Lyα luminosity function
7018 spectra extracted in 5 deep exposures(5.65sq.deg)
→96 Lyα emitting galaxy candidates
Wavelength range Å for Lyα
　　　　　　　　　　　 　(z = )
・Properties of the Lyα emitting galaxies
・The Lyα luminosity function

7. Properties of the Lyα emitting galaxies
Distribution of Lyα EW
Compare LF(0.2 < z < 0.35)
Arnouts et al.(2005)
Shapley et al.(2003)LBGs (z～3)
→25%
EW > 20Å Lyα emitting galaxies
21 mag(AB) →　9(out of 58)
→ 36(out of 243)
→the same 15%
Lyα EW are consistent with stellar population model.

8. Properties of the Lyα emitting galaxies
Lyα dependences: GALEX data
No trends as function of UV color or UV luminosity.

9. Properties of the Lyα emitting galaxies
The (u-r) vs. (NUV-r) color-color diagram
Shows a sequence in good agreement
→LyαEW (without any transfer) is predicted
rather stable as a function of time in galaxies
with constant star formation.

10. The Lyα luminosity function
Comparisons with Hα LF
Used the Hα luminosity function of Tresse &Maddox(1998)
Log(L*)=41.92ergs s^-1
Log(Φ*)=-2.56mpc^-3
Lyα luminosity function the same value
α=-1.35 as determined for the Hα LF
●all five filed
■CDFS,GROTH,NGPDWS
○with an evaluation accounting
for incompleteness
Comparison with Hα LF is consistent with an average Lyα/Hα of～1 in about 15% of the star-forming galaxies

11. The Lyα luminosity function
Comparisons with Lyα LF at high z
Comparison with high-redshift Lyα LF implies increase of the Lyα density by factor of about 16 from z～0.3 to z～3.