1 / 25

Early Star Formation and Dust Emission at z~6: A Modest Overview

This overview discusses the importance of dust at high redshifts, its role in early star formation and molecular hydrogen formation, its detectability through far-infrared and near-infrared observations, and the sources of dust production. It also explores the constraints and theoretical predictions on the presence and destruction of dust at z~6.

darrellsanchez
Download Presentation

Early Star Formation and Dust Emission at z~6: A Modest Overview

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A modest overview of HIGH-REDSHIFT DUST Simona Gallerani (Astronomical Observatory of Rome) in collaboration with: R. Maiolino; Y. Juarez; T. Nagao; L. Jiang; X. Fan; C. Willott; R. Mortlock

  2. DAVID The Dark Ages VIrtual Department http://www.arcetri.astro.it/twiki/bin/view/DAVID/WebHome S. Bianchi INAF/Arcetri B. Ciardi MPA P. Dayal SISSA C. Evoli SISSA A. Ferrara SNS Pisa S. Gallerani OARoma F. Iocco IAP F. Kitaura SISSA M. Mapelli ETH A. Maselli MPA R. Salvaterra INAF/Milano S. Salvadori SISSA R. Schneider INAF/Arcetri L. Tornatore INAF/Trieste M. Valdes IPMU R. Valiante Univ. Firenze

  3. Dust at z~6why do we care? • Early star formation • Trigger molecular hydrogen formation • Allows low mass star formation at low metallicities • Far-Infrared emission • Detectability at mm-submm wavelengths • UV-Optical extinction and reddening • Detectability and interpretation of near-IR light

  4. WARM (T~10-100 K)DUST EMISSION Evidence for large dust masses! Mdust ~ 108 M REST FRAME FAR-IR OBSERVATIONS OF z~6 QSOS Mdust = 4 ×108 M Sharc II SCUBA MAMBO Spitzer F (mJy) VLA lrest (mm) (e.g. Beelen et al. 06; Priddey et al. 03; Bertoldi et al. 03) In a sample of 33 QSOs at z~6, 30% of these objects have been detected in the FIR, as in lower redshift samples. (Wang et al. 2008)

  5. REST FRAME NEAR-IR OBSERVATIONS OF z~6 QSOS Spitzer OBS=24m RF~3m rest z ~ 6 low-z QSOs HOT (T~1000-2000 K)DUST EMISSION Most z~6 QSOs have similar hot dust emission as low-z QSOs Emission from the hot dust on the inner side of circumnuclear clouds not sensitive to the total dust content ...as long as you have some dust! Jiang et al. 2006

  6. AGN REST FRAME NEAR-IR OBSERVATIONS OF z~6 QSOS But 2 QSOs do NOT show any hot dust emission! Never observed in QSOs at low-z. Possible cases of very young objects where dust had no time to form yet? Jiang et al. 2006

  7. Sources of Dust Mostly produced by evolved low mass stars (AGBs) 108 AGBs 106 Dust Mass (M) but bulk of dust (>90%) produced after 1 Gyr 104 (e.g. Morgan & Edmunds 2003) first AGBs at ~40 Myr... 102 0.01 0.1 1 10 Age (Gyr)

  8. Sources of Dust at z~6 Age of the Universe < 1 Gyr redshift 10 6 1 0 108 SN dust ? QSO dust ? ... ? AGBs 106 Dust Mass (M) 104 102 0.01 0.1 1 10 Age (Gyr)

  9. SNe as dust factories at z~6 reverse shocks may also destroy a significant amount of dust (Bianchi & Schneider 07; Hirashita et al. 08; Nozawa et al. 09) Observational constraints Theoretical predictions Ydust = 10-4 - 0.3 M/SN (Krause et al. 04; Meikle et 06; Sugerman et al. 06; Kotak et al. 09) Ydust = 0.1- 1 M/SN (e.g. Todini & Ferrara 01; Nozawa et al. 03) Ydust = 2 - 4 M/SN (CasA by Dunne et al. 03) only 2-20 % of the dust survive! (Bianchi & Schneider 07; Hirashita et al. 08; Nozawa et al. 09) The presence of 108M of dust can be explained through SN production assumin an extreme 100% efficiency of dust formation or a Top Heavy IMF. (Dwek et al. 08)

  10. Can SNe alone account for the observed dust masses at z~6? mISM ISM mass cleared of dust Ydust=1.2 M no destruction Ydust=0.4 M Dust Yield per SN (M) J1148 z = 6.4 tg~400Myr Zd~0.07 Zd=Md/Mg Md=2×108M ; Mg~3×1010M (Dwek et al. 07) (Bianchi & Schneider 07; Hirashita et al. 08; Nozawa et al. 09) The presence of 108M of dust can be explained through SN production assumin an extreme 100% efficiency of dust formation or a Top Heavy IMF. (Dwek et al. 08)

  11. Can SNe alone account for the observed dust masses at z~6? Dust Yield per SN (M) J1148 z = 6.4 tg~400Myr Zd~0.07 M0=5×1010M Mstar=2×1010 M<<5×1012M (MBH=5×109M ; Willott 03; Barth 03) SFR=50 M/yr <<3000 M/yr (Bertoldi et al. 03) Zd=Md/Mg Ydust are overestimated by at least a factor of 10! YES! SNe can make it (Bianchi & Schneider 07; Hirashita et al. 08; Nozawa et al. 09) The presence of 108M of dust can be explained through SN production assumin an extreme 100% efficiency of dust formation or a Top Heavy IMF. (Dwek et al. 08)

  12. Can SNe alone account for the observed dust masses at z~6? Valiante et al. 09 total dust mass the AGB role revisited carbon dust other dust silicate dust 80% AGB-dust Star formation history by Li et. al. 07; Larson IMF; Ferrarotti & Gail 06 AGB-dust yields; Bianchi & Schneider 07 SN-dust yields

  13. EXTINCTION CURVE at z<4 (Quasars) dusty wind Reddening BAL are the most reddened sub-class of (type 1) QSOs SMC-like extinction curve as for noBAL QSOs at 0<z<2.2 Reichard et al. 2003 Richards et al. 2003; Hopkins et al. 2004

  14. EXTINCTION CURVE at z~6 (Quasars) SDSS1048+46 BAL at z=6.23 (Todini & Ferrara 01) Bluer than any BAL at low z (Maiolino et al.04) (Maiolino et al. 04) Extinction curve consistent with properties of dust theoretically expected from SNe Also in agreement with Bianchi & Schneider 07 and Hirashita et al. 2008 predictions

  15. EXTINCTION CURVE at z~6 (Gamma Ray Bursts) Galactic (A3000Å=1.49) SMC (A3000Å=0.8) K Z J H GRB050904 at z=6.3 0.5 days after the burst SN dust (A3000Å=2) =QSO J1148 z=6.2 Calzetti (A3000Å=2) Data from Haislip et al. 06 Stratta et al. 06

  16. A SAMPLE of 33 OPTICAL/NIR SPECTRA of QSOs a 4<z<6.4 (Juarez et al. 2009; Jiang et al. 2007; Willott et al. 2009; Mortlock et al. 2008) Ftempl template by Reichard et al. 2003, having α=-1.62 A3000 absolute extinction at 3000 Å Aextinction curve normalized at 3000 Å 9 QSOs require substantial (A3000~[0.4-1.8]) reddening

  17. EXTINCTION CURVES Z=0 Z=Z before rs after rs Todini & Ferrara 01 Bianchi & Schneider 07 nH=0.1cm-3 mixed after rs nH=1cm-3 mixed after rs unmixed before rs nH=0.1cm-3 unmixed after rs 20 M 170 M mixed nH=1cm-3 unmixed Hirashita et al. 08 Hirashita et al. 08

  18. DUST REDDENING IN 4<z<6.4 QSOs RF [Å] RF [Å]

  19. DUST REDDENING IN 4<z<6.4 QSOs RF [Å] RF [Å]

  20. DEVIATION FROM THE SMC in z>4 QSOs Extinction curve at z<4 Mean Extinction curve at z>4 different chemical composition? grain size distribution? Evidence for different dust properties in the early Universe

  21. BAL vs noBAL REDDENING in z>4 QSOs

  22. EFFECTS OF DUST ON EARLY STAR FORMATION

  23. H2 formation on dust grains (Omukai & Nishi 02; Glover 03; Cazaux & Spaans 04) Md/Mg = 5×10-4 Md/Mg= 5×10-5 Md/Mg =0 SN 12-25 M; 0.1 ≤ Yd ≤ 0.3; 50 SNe (Mvir, zvir) = (109 M, 10) (Todini & Ferrara 01) (Hirashita & Ferrara 02) PISN 195 M; Yd ~ 0.3; 1 PISN (Schneider et al. 04)

  24. 2 – 0 – -2 – -4 – -6 - >100M - - - - ~1M logξ -1 0 1 2 logM/M Transition from massive PopIII to normal PopII/I stars Present day star forming regions Salpeter IMF Primordial star forming Regions (Omukai 2000; Abel et al. 2002) PopIII PopII Z>Zcr (Schneider et al. 2006) M(frag) [M] 10-6 Z≤Zcr≤ 5×10-3 Z (Schneider et al. 2002; 2003; Omukai et al. 2005)

  25. Summary • Clear evidence for dust at z~6 and beyond • Indications of a decreasing amount of dust at z~6 • (to be verified with ALMA, Herschel and JWST) • SN dust can account for dust masses at z~6, but also the AGB contribution should not be neglected. • Deviation of the mean extinction curve at z>4 from the SMC which characterizes the reddening of QSOs spectra at lower redshifts. • Important implications of dust for the early star formation

More Related