MOLECULAR GAS AND THE HOST-GALAXY SYSTEM OF THE z {approx} 0.3 QSO PG 1700+518
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)
- Space Science Institute, 4750 Walnut St., Suite 205, Boulder, CO 80301 (United States)
- Kapteyn Astronomical Institute, P.O. Box 800, Groningen, AV9 700 (Netherlands)
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- Spitzer Science Center, Pasadena, CA 91125 (United States)
- Institute of Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States)
- Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States)
The detection of CO(1{yields}0) emission in the massive (i.e., M {sub H} {approx} -26.13 mag), z {approx} 0.3 host-galaxy system of the broad absorption line quasi-stellar object (QSO) PG1700+518 is reported. The host system has a CO luminosity of L'{sub CO} {approx} 1.4 x 10{sup 10} K km s{sup -1} pc{sup 2}, and thus a star-forming molecular gas mass of M(H{sub 2}) {approx} 6 x 10{sup 10} M {sub sun} (adopting an {alpha} = 4 M {sub sun} [K km s{sup -1} pc{sup 2}]{sup -1}), making it one of the most molecular gas-rich Palomar-Green QSO hosts observed to date. New Hubble Space Telescope WFPC2 direct and NICMOS coronagraphic images show the highest resolution view yet of the host and companion. The new NICMOS image reveals the underlying, apparently tidally disrupted structure seen previously from high-resolution ground-based optical imaging. Light from the host galaxy is overwhelmed by the central point source in the WFPC2 images. The companion galaxy is well resolved in both data sets, and the WFPC2 provides for the first time a clear picture of the optically visible ring structure. The CO redshift is within the range of redshifts derived from optical QSO emission lines, thus the observed CO is associated with the QSO host. However, it cannot be ruled out that the companion has at least {approx}10{sup 10} M {sub sun} of molecular gas. Finally, if the far-infrared luminosity, which is 1/5 of the bolometric luminosity, is the luminosity of the starburst population, the star formation rate is estimated to be {approx}210 M {sub sun} yr{sup -1}. There is thus sufficient molecular gas in the QSO host galaxy to fuel both star formation and QSO activity for another {approx}10{sup 8} yr. We speculate that we may be witnessing the fueling event in progress that resulted from a collision between the QSO host and the companion galaxy, and that there is an accompanying expulsion of material along our line of sight in the form of broad absorption line gas.
- OSTI ID:
- 21255687
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 138, Issue 1; Other Information: DOI: 10.1088/0004-6256/138/1/262; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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