NOAO >   Observing Info >   Approved Programs >   2012A-0038

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Proposal Information for 2012A-0038


PI: John T. Stocke, Univ. of Colorado, john.stocke@colorado.edu
Address: CASA, 389 UCB, Boulder, CO 80309, USA

CoI: Ting Yan, Univ. of Colorado
CoI: Jeremiah K. Darling, Univ. of Colorado
CoI: Nissim Kanekar, GMRT, NCRA, TIFR, India

Title: Highly Obscured Radio-Loud Quasars

Abstract: We propose to obtain low-resolution GMOS spectra of our 8 best candidates for highly obscured quasars using a unique new FIRST + SDSS selection process that has already shown end-to-end success. The ultimate goals of this work are to measure the physical properties of molecular clouds as a function of redshift and to determine whether fundamental constants like the fine-structure-constant ((alpha)) have changed with cosmic time. Our radio spectroscopy technique does not suffer from the calibration difficulties that plague optical work which suggests an \dot(alpha) value several times larger than the limits we have established at slightly lower redshifts. So we expect to test the optical results definitively using new sources found at z\gtrsim1. Measuring accurate redshifts for these bright (> 300 mJy) sources is an \bfessential \bf step because the low-frequency (< 1 GHz) radio spectrum is riddled with interference (RFI) which severely limits our ability to detect H I 21cm and molecular absorption lines; a precise search frequency is needed even to decide which radio observatory to employ. Currently only 5 redshifted molecular absorbers are known; even one new absorber at z\gtrsim1 will impact this field of study. Already three new H I absorbers and one new gravitationally-lensed quasar have been discovered in this program.


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