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
The Dark Ages VIrtual Department 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 2
Dust at z~6 why do we care? Early star formation Far-Infrared emission 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
REST FRAME FAR-IR OBSERVATIONS OF z~6 QSOS Evidence for large dust masses! Mdust ~ 108 M WARM (T~10-100 K) DUST EMISSION 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)
REST FRAME NEAR-IR OBSERVATIONS OF z~6 QSOS Spitzer OBS=24m RF~3m 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
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. AGN Possible cases of very young objects where dust had no time to form yet? Jiang et al. 2006
Sources of Dust Mostly produced by evolved low mass stars (AGBs) AGBs 108 AGBs 106 Dust Mass (M) but bulk of dust (>90%) produced after 1 Gyr 104 first AGBs at ~40 Myr... (e.g. Morgan & Edmunds 2003) 102 0.01 0.1 1 10 Age (Gyr)
Sources of Dust at z~6 Age of the Universe < 1 Gyr SN dust ? 10 6 1 redshift 108 SN dust ? QSO dust ? ... ? AGBs 106 Dust Mass (M) According to this scenario little dust is expected to be present at z>5 when the Universe was younger than 1 Gyr. Thus, in order to explain the huge amounts of dust inferred from observations different sources of dust have been invoked, as SN or QSO winds. Is there dust? Evolution of dust mass? Evolution of dust properties? Clues on the dust production mechanism? Account for dust mass? Implications for detectability and observational properties? 104 102 0.01 0.1 1 10 Age (Gyr)
SNe as dust factories at z~6 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) reverse shocks may also destroy a significant amount of dust (Bianchi & Schneider 07; Hirashita et al. 08; Nozawa et al. 09) only 2-20 % of the dust survive! (Bianchi & Schneider 07; Hirashita et al. 08; Nozawa et al. 09) The presence of 108 M 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)
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 108 M 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)
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 108 M 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)
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
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
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
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) Simple screen case, known intrinsic spectrum Data from Haislip et al. 06 Stratta et al. 06
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) Ftempl 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
EXTINCTION CURVES Z=0 Z=Z before rs after rs nH=0.1cm-3 mixed Todini & Ferrara 01 Bianchi & Schneider 07 nH=0.1cm-3 mixed after rs nH=1cm-3 unmixed before rs 20 M 170 M mixed nH=1cm-3 unmixed Hirashita et al. 08 Hirashita et al. 08
DUST REDDENING IN 4<z<6.4 QSOs RF [Å] RF [Å]
DUST REDDENING IN 4<z<6.4 QSOs RF [Å] RF [Å]
grain size distribution? 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
BAL vs noBAL REDDENING in z>4 QSOs
ON EARLY STAR FORMATION EFFECTS OF DUST ON EARLY STAR FORMATION
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) PISN 195 M; Yd ~ 0.3; 1 PISN (Hirashita & Ferrara 02) (Schneider et al. 04)
Transition from massive PopIII to normal PopII/I stars Present day star forming regions Salpeter IMF logξ 2 – 0 – -2 – -4 – -6 - -1 0 1 2 logM/M - ~1M >100M 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)
Summary Indications of a decreasing amount of dust at z~6 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 Possibly, both AGBs SNe and QSO winds may contribute to the dust enrichment in the early Universe.