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

2. IntroductionIntroduction 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. Tremaine et al. (2002) Marconi & Hunt. (2002) M BH ~σ 4 M BH ~10 -3 M Bulge IntroductionIntroduction

4. SampleSample 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 m 1450A < 20. Nine from deeper optical imaging with m 1450A >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. SHARC-II CSO ObservationsObservations MAMBO IRAM-30m

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

7. Star formation in the mm non-detections The average FIR luminosity: 1.2x10 12 L sun –Even 50% of the FIR emission from star formation, the star formation rate => 200 M sun 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: ≥10 8 M sun FIR luminosity ~ 10 13 L sun

10. Luminosity correlation L FIR - L Bol Wang et al. (2008 in press)

11. Luminosity correlation L FIR – 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: ≥ 10 3 M sun yr -1 –Active bulge building via massive star formation co-eval with SMBH accretion.

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

15. L FIR & Lya emission 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… Wang et al. (2008 in press)

16. 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 M sun yr -1. The millimeter detected quasars tend to have weak UV line emission. SummarySummary

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