SIMBAD references

begin{HTML} We present new results of a deep optical imaging survey using a narrow band filter (<I>NB921</I>) centered at l = 9196 Å together with <i>B, V, R, i'</i>, and <i>z'</i> broadband filters in the sky area of the Subaru Deep Field, which has been promoted as one of legacy programs of the 8.2m Subaru Telescope. We obtained a photometric sample of 58 Ly a emitter candidates at z ~6.5-6.6 among ∼ 180 strong <I>NB921</I>-excess (<I>z'</I> - <i>NB921</i> > 1.0) objects together with a color criterion of <i>i' - z'</i> > 1.3. We then obtained optical spectra of 20 objects in our <I>NB921</I>-excess sample, and identified at least nine Ly a emitters at <i>z</i> ∼ 6.5-6.6, including the two emitters reported by Kodaira et al. (2003, PASJ, 55, L17). Since our Ly a-emitter candidates are free from strong amplification of gravitational lensing, we are able to discuss their observational properties from a statistical point of view. Based on these new results, we obtained a lower limit of the star-formation rate density of r_SFR ≃5.7 x 10^-4 <i>h</i>_0.7 <i>M</i> _☉ yr^-1 Mpc^-3 at <i>z</i> ~6.6, being consistent with our previous estimate. We discuss the nature of star-formation activity in galaxies beyond <i>z<i> = 6.