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Multiple CO Transitions, C i , and HCN from the Cloverleaf Quasar

1997; IOP Publishing; Volume: 484; Issue: 2 Linguagem: Inglês

10.1086/304382

1538-4357

Richard Barvainis, Philip R. Maloney, Robert Antonucci, D. Alloin,

Astrophysical Phenomena and Observations

New millimeter-wavelength emission lines are reported for the Cloverleaf (H1413+117), a gravitationally lensed quasar at redshift 2.56. High signal-to-noise ratio (S/N) spectra of four lines in CO (3 → 2, 4 → 3, 5 → 4, and 7 → 6) have been obtained and are modeled with an escape probability formalism. The line brightness temperatures are flat or rising between CO (3 → 2) and CO (4 → 3) and then drop to the CO (5 → 4) and CO (7 → 6) lines; this falloff suggests that the optical depths in the CO lines are modest (τ4-3 ≲ 3) and that the gas is relatively warm (T ≳ 100 K) and dense (nH2 ≳ 3 × 103 cm-3).