Astrophys. J., 690, 463-485 (2009/January-1)
Imaging the molecular gas in a z = 3.9 quasar host galaxy at 0".3 resolution: a central, sub-kiloparsec scale star formation reservoir in APM 08279+5255.
RIECHERS D.A., WALTER F., CARILLI C.L. and LEWIS G.F.
Abstract (from CDS):
We have mapped the molecular gas content in the host galaxy of the strongly lensed high-redshift quasar APM 08279+5255 (z = 3.911) with the Very Large Array at 0".3 resolution. The CO(J = 1 -> 0) emission is clearly resolved in our maps. The CO(J = 1 -> 0) line luminosity derived from these maps is in good agreement with a previous single-dish measurement. In contrast to previous interferometer-based studies, we find that the full molecular gas reservoir is situated in two compact peaks separated by ≲0".4. Our observations reveal, for the first time, that the emission from cold molecular gas is virtually co-spatial with the optical/near-infrared continuum emission of the central active galactic nucleus (AGN) in this source. This striking similarity in morphology indicates that the molecular gas is situated in a compact region close to the AGN. Based on the high-resolution CO maps, we present a revised model for the gravitational lensing in this system, which indicates that the molecular gas emission is magnified by only a factor of 4 (in contrast to previously suggested factors of 100). This model suggests that the CO is situated in a circumnuclear disk of ∼550 pc radius that is possibly seen at an inclination of ≲25°, i.e., relatively close to face-on. From the CO luminosity, we derive a molecular gas mass of Mgas= 1.3x1011 M ☉ for this galaxy. From the CO structure and linewidth, we derive a dynamical mass of Mdynsin2 i = 4.0x1010 M☉. Based on a revised mass estimate for the central black hole of MBH= 2.3x1010 M☉ and the results of our molecular line study, we find that the mass of the stellar bulge of APM 08279+5255 falls short of the local MBH-σbulge relationship of nearby galaxies by more than an order of magnitude, lending support to recent suggestions that this relation may evolve with cosmic time and/or change toward the high-mass end.
cosmology: observations - galaxies: active - galaxies: formation - galaxies: high-redshift - galaxies: starburst - radio lines: galaxies
Calibrators 0749+540 and 0820+560 not identified.
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