M. Rodríguez, M. Villar Martín, B. H. C. Emonts, A. Humphrey, G. Drouart, S. García Burillo, M. Pérez Torres

Abstract
We present new results of CO(1–0) spectroscopic observations of four Sloan Digital Sky Survey (SDSS) type 2 quasars (QSO2) at z ~ 0.3, observed with the 30-m IRAM radio telescope. The QSO2 have infrared luminosities in the ultra-luminous infrared galaxies (ULIRG) regime. We confirm the CO(1–0) detection in one of our four QSO2, SDSS J1543-00, with L′_CO and M_H2 (1.2 ± 0.2) × 10¹⁰ K km s^-1  pc² and (9.4 ± 1.4) × 10⁹ M _⊙, respectively. The full width at half maximum (FWHM) of the CO(1–0) line is =575 ± 102 km s^-1. No CO(1–0) emission is detected in SDSS J0903+02, SDSS J1337-01, SDSS J1520-01 above 3 sigma, yielding upper limits on M(H₂) ~ 9.6, 4.3 and 5.1 × 10⁹ M_⊙, respectively. We expand previous studies of the molecular gas content of intermediate z QSO2 into the ULIRG regime. Taking into account nine QSO2 at z ~ 0.3–1.0 from the literature, we discuss the location of the 13 ULIRG QSO2 at z < 1 with available L′_CO measurements in the L′_CO vs. z and L′_CO vs. L_FIR diagrams, in comparison with other QSO1 and ULIRG star forming samples.

Keywords
quasars: general – quasars: emission lines – galaxies: ISM

Astronomy & Astrophysics
Volume 565, Number of pages A19_1
2014 May

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