Identification Spectroscopy of Two 5.5<z<6.5 Quasar Candidates
PI:
Patrick Hall
Co-I(s):
Laura Chajet, Jesse Rogerson, Howard Yee, Michael Gladders, David Gilbank, Felipe Barrientos, Michael De Robertis
Abstract
Quasars at z>5.5 probe the reionization of the universe via absorption studies of the intergalactic medium.
Our present understanding of reionization is limited partially by cosmic
variance: different sightlines show different IGM optical depths at the
same redshift. To overcome cosmic variance at redshift z requires 200 quasar
sightlines at redshift z+0.3, but only ~35 z>5.5 quasars are known to date.
We have identified five z>5.5 quasar candidates (including a known z=6.12 quasar) via
near-IR imaging of 163 objects with extremely red R-z' colors from the
90-square-degree Red-sequence Cluster Survey.
These candidates deviate from the (R-z',z'-J) colors expected
for late-type dwarf stars at significance levels >=3.5 sigma.
We request spectroscopy of two B-semester candidates.
Our candidates are fainter than z>5.5 quasars from the main SDSS survey, but there are not
enough quasars at those magnitudes to overcome cosmic variance.
Therefore, any quasars we discover will be targets for extensive followup.