Millimeter and Radio studies of z~6 Quasars

1. Millimeter and Radio studies of z~6 Quasars Ran Wang Department of Astronomy, Peking University, China Supervisor: Chris Carilli ( NRAO), Xue-Bing Wu (PKU) Collaborators: Bertoldi, F. (University of Bonn); Cox, P. (IRAM); Fan, X. (University of Arizona); Jiang, L. (University of Arizona); Menten, K. (MPIfR); Omont, A. (IAP); Strauss, M. (Princeton); Wagg, J. (NRAO); Walter, F. (MPIfA)

2. Introduction – The discovery of z~6 quasars 1148+5251 z=6.42 Beelen et al. 2006 Walter et al. 2004; Carilli et al. 2008

3. Introduction • We are pursuing cm and mm studies of all the quasars discovered at z~6

4. Sample • There are totally Thirty-three quasars discovered at z~6. • z=5.71 to 6.43 • M_1450A < -25.0 • Twenty-two from the SDSS survey of ~8000 deg^2 area, with m1450A < 20. • Nine from deeper optical imaging with m1450A>20, Jiang et al. 2007; Wollitt et al. 2007 • IR (Spitzer) + optical: one; Cool et al. (2006) • Radio (FIRST) + optical: one; McGreer et al. (2006) Most of these objects were optically selected from the SDSS survey Represent the most luminous quasar population at z~6.

5. Observations MAMBO IRAM-30m VLA PdBI IRAM SHARC-II CSO

6. A summary of the (sub)mm and radio Results • MAMBO observations of 33 sources • rms in the range of 0.4 to 1.1 mJy with a median value of 0.6 mJy • Ten are detected at ≥ 3 σ level • VLA observation of 32 sources • rms ≤ 20 uJy for most of the sources • Ten were detected, with two of them having flux densities > 1mJy • Three of them have radio loudness R ≥10 • CO observations of the bright mm detections.

7. The average FIR and radio emission Wang et al. (2008 submitted) FIR-millimeter spectral index ~2

8. The bright millimeter detections • The FIR emission exceeds that of the local quasar template. • The FIR SED is consistent with optically thin gray-body emission from 40 ~ 50 K dust. • The FIR-to-radio SED is consistent with that of typical star forming galaxies. • Dust mass: ≥108 Msun • FIR luminosity ~ 1013 Lsun • Observations at 2mm and 3mm will determine the emissivity index.

9. CO detections • Molecular CO emission has been detected in the mm bright quasars. • Gas mass : M(H2) ≥ 1010 Msun. • CO line width of the new detections: FWHM ≥ 500 km/s • The median value is 300 km/s for previous CO detected quasars at high-z. Carilli et al. 2007

10. Luminosity correlation LFIR – L’CO

11. Luminosity correlation LFIR - LBol Wang et al. (2008 in press)

12. Discussion – star formation in the z~6 quasars • The MAMBO undetected quasars at z~6: • The average FIR-to-radio SED is consistent with the templates of local optical quasars. • The average FIR to AGN-bolometric luminosity ratio follows the trend defined by local PG quasars. • The average FIR luminosity: 1.2x1012 Lsun • Even 50% of the FIR emission from star formation, the star formation rate => 200 Msun yr-1 • The major bulge building stage via starburst has been finished ?

13. Discussion – star formation in the z~6 quasars • The mm and CO detected quasars at z~6: • FIR emission from 40 ~ 50 K warm dust. • Properties similar to that of star forming galaxies. • Derived star formation rate: ≥ 103 Msun yr-1 • Gas depletion time: Mgas/SFR ~ 107 yr . • Active bulge building via massive star formation co-eval with SMBH accretion. • Black hole-bulge mass ratio : high-resolution CO mapping.