NOAO >   Observing Info >   Approved Programs >   2002A-0191

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Proposal Information for 2002A-0191


PI: Haojing Yan, Arizona State University, yhj@asu.edu
Address: Box 871504, Tyler Mall PSF-470, Tempe, AZ 85287-1504, USA

CoI: Stephen C. Odewahn, Arizona State University
CoI: Seth H. Cohen, Arizona State University

Title: An Intermediate-band z~6 Drop-out Search: Constrain the Luminosity Function of Objects at Reionization

Abstract: The recent detection of a complete Gunn-Peterson trough in a z=6.28 SDSS quasar suggests that we have seen the trailing end of the Universe reionization era at z~eq 6. The galaxy number counts at this redshift, therefore, will have even greater cosmological impact than ever. We propose a drop-out search for 5.5<=z <=6.5 objects using four medium-band filters with the KPNO-4m + MOSAIC, aiming at a detection limit of m_AB(910nm)~eq 24.5 mag. The four filters cover the spectral range of 802-974 nm and avoid the strongest night-sky emission lines to yield as faint a sky-background as possible. We will cover 0.64 deg^2 (two MOSAIC fields) in the 2002A semester. The resulting number of candidates will put strong constraint on the luminosity function of z~eq 6 objects. Our survey will fill in the gap between the bright end (< 21 mag), which can only be addressed by the all-sky surveys such as the SDSS, and the faint end (> 27 mag), which is only accessible to the ultra-deep pencil-beam programs utilizing the HST. Our pilot run at the CTIO-4m in June 2000 shows that \ksmbf the combination of our filters and the wide-field mosaic cameras at 4m-class telescopes is currently the only realistic way to access the luminosity function of z~eq 6 objects at intermediate brightness level. We expect to yield about ten z~eq 6 objects, and will be able to significantly constrain the luminosity function at z~eq 6. Even in a case of a null-detection, the depth and coverage of our survey will allow us to derive a stringent limit. Based on what we know about the z~eq 3 galaxies, our result will also constrain how the luminosity function of galaxies evolves from z~eq 3 to z~eq 6.


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