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The molecular gas content of ULIRG type 2 quasars at z < 1

M. Rodríguez, M. Villar-Martín, B. 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 LCO and MH2 (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 LCO measurements in the LCO vs. z and LCO vs. LFIR diagrams, in comparison with other QSO1 and ULIRG star forming samples.

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

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

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia