Warm Dust in the Most Distant Quasars

1. Warm Dust in the Most Distant Quasars Ran Wang Department of Astronomy, Peking University, China

2. Introduction • Why looking for dust at z~6 • The mass of dust in the earliest and most massive galaxies: dust formation within 1 Gyr. • The dust temperature, distribution, and Luminosity: dust heating quasar systems.  FIR luminosity SFR  evolutionary stage of the black hole – bulge system.

3. Introduction Marconi & Hunt. (2002) Tremaine et al. (2002) MBH~10-3MBulge MBH~σ4

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; Willott 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 SHARC-II CSO

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

7. Star formation in the mm non-detections • 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 ?

8. The SEDs of millimeter detections

9. 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

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

11. Luminosity correlation LFIR – L’CO

12. 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 • Active bulge building via massive star formation co-eval with SMBH accretion.

14. LFIR & Lya emission Omont et al. (1996): Three kinds of spectra from z>4 quasars

15. LFIR & Lya emission Wang et al. (2008 in press) • Quasars at z~6: • Most of the millimeter detections tend to have log(EW)Lya < 1.5. • The origin of this effect is not clear yet. • More observations…

16. Summary • We studied the (sub)millimeter emission from the host galaxies of quasars at z~6. • About 30% of these sources have been detected in warm dust continuum at 1.2 mm. • The average FIR-to-radio SED of the non-detected sources is comparable to that of local optical quasars. • Obvious FIR excesses in the SEDs of the strong millimeter detections. • FIR dust heating dominated by Star formation at a rate of a few 1000 Msun yr-1 . • The millimeter detected quasars tend to have weak UV line emission.

17. Introduction – The discovery of z~6 quasars 1148+5251 z=6.42 Bertoldi et al. (2003) Beelen et al. 2006