Warm dust in the most distant quasars
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Warm Dust in the Most Distant Quasars. Ran Wang Department of Astronomy, Peking University, China. Introduction. Why looking for dust at z~6 The mass of dust in the earliest and most massive galaxies: dust formation within 1 Gyr.

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Warm dust in the most distant quasars

Warm Dust in the Most Distant Quasars

Ran Wang

Department of Astronomy, Peking University, China


Introduction

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.


Warm dust in the most distant quasars

Introduction

Marconi & Hunt. (2002)

Tremaine et al. (2002)

MBH~10-3MBulge

MBH~σ4


Sample

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.


Observations

Observations

MAMBO IRAM-30m

SHARC-II CSO


The average fir and radio emission

The average FIR and radio emission

Wang et al. (2008 submitted)

FIR-millimeter spectral index ~2


Star formation in the mm non detections

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 ?


Warm dust in the most distant quasars

The SEDs of millimeter detections


Warm dust in the most distant quasars

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


Luminosity correlation l fir l bol

Luminosity correlation LFIR - LBol

Wang et al. (2008 in press)


Luminosity correlation l fir l co

Luminosity correlation LFIR – L’CO


Star formation in the z 6 quasars

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.


Warm dust in the most distant quasars

LFIR & Lya emission

Omont et al. (1996): Three kinds of spectra from z>4 quasars


L fir lya emission

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…


Warm dust in the most distant quasars

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.


Introduction the discovery of z 6 quasars

Introduction – The discovery of z~6 quasars

1148+5251 z=6.42

Bertoldi et al. (2003)

Beelen et al. 2006


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