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Astronomy Tea Talks at Caltech

Mondays, Hameetman auditorium (Cahill)
Tea:  4.00pm
Talk: 4.15pm

Organized by:

2010 - 2011 season:
24 January 2011 Ran Wang

'Millimeter Study of Quasar-Host Galaxy Evolution at z~6'

We present our millimeter study of the dust and molecular gas componenets in the host galaxies of the quasars at z~6. We search for 250 GHz continuum in more than 30 z~6 quasars, including the most luminous objects (i.e., 18.8 < m1450 A<20.7) from the SDSS main survey and the optically fainter sample (i.e., 20.2 < m1450A<22.3) selected from the SDSS southern deep field. The observations have been performed using the Max Plank Millimeter Bolometer Array (MAMBO) on the IRAM-30m telescope, and millimeter dust continuum has been detected in about 30% of these z~6 quasars. We search for molecular CO line emission in ten of the strongest MAMBO detections using the IRAM Plateau de Bure Interferometer, and nine of them have been detected. The detections indicate strong FIR emission (L_fir~a few 1012 to 1013 Lsun) from 40 to 60 K warm dust and 1010 Msun of highly excited molecular gas in the host galaxies of the z~6 quasar with AGN luminosities over a wide range. We investigate the FIR-CO and FIR-AGN luminosity correlations of these z~6 quasars by comparing them to the AGN-starburst systems at local and high-z universe. It is likely that massive star formation at rates of a few hundred to 1000 Msun/yr is ongoing in the host galaxies of the FIR and CO luminous z~6 quasars. Their molecular gas masses and FIR-to-CO luminosity ratios (i.e., star formation efficiency) are similar to that of the extreme starburst systems, such as the submillimeter galaxies. Moreover, the detections of strong FIR dust emission in the optically faint quasars at z~6 may suggest a higher ratio between star formation rate and supermassive black hole accretion rate in these systems compared to that of the optically bright ones.
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Last modified on 20th Jul 2011 by Dominik A. Riechers.  

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