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Mikako Matsuura Origin’s fellow, Institute of Origins, University College London

Origin and evolution of dust in galaxies Spitzer Observations of Dust in the Local Group Galaxies Implications for dust in high- z galaxies. Mikako Matsuura Origin’s fellow, Institute of Origins, University College London. Team. Mikako Matsuura M. J. Barlow Greg Sloan Kevin Volk

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Mikako Matsuura Origin’s fellow, Institute of Origins, University College London

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  1. Origin and evolution of dust in galaxiesSpitzer Observations of Dust in the Local Group Galaxies Implications for dust in high-z galaxies Mikako Matsuura Origin’s fellow, Institute of Origins, University College London

  2. Team • Mikako Matsuura • M. J. Barlow • Greg Sloan • Kevin Volk • Jeronimo Bernard-Salas • Tom Llyod-Evans • You-Hua Chu • Robert Gruendl • Bruce J. Hrivnak • YoshifusaIta • Kathleen Kraemer • Eric Lagadec • Quentin A Parker • Warren Reid • Takashi Shimonishi • E. van de Are • H. van Winkle • Peter Wood • Albert Zijlstra • Karl Gordon • Remy Indebetouw • Ciska Kemper • Massimo Marengo • Margaret Meixner • XanderTielens • Jacco van Loon • Paul Woods The orign and evolution of dust in galaxies

  3. Introduction: IR emission • Infrared (IR) emission of galaxies • Thermal emission from dust grains • Indicator of starformation rate • What is the origin of dust? • Origin/quantity • Can we account for dust mass in the interstellar medium (ISM) by stellar sources? • Effects of different metallicities • Dust compositions • Dust formations Log (λ * Lλ) (L) 0.1 1 10 100 1000 Wavelength (micron) Infrared Dacunha et al. (2008) The orign and evolution of dust in galaxies

  4. Origin and quantity • Effects of metallicities • Dust compositions • Dust formation • Implication for the distant galaxies

  5. Cycle of matter (gas and dust) in galaxies Important for galaxy evolution Concept of cycle of matter Past: Theory/models (population synthesis/chemical evolution models of galaxies) 1- 8(10?) M Current: measurements of dust >8(10?) M The orign and evolution of dust in galaxies

  6. Large Magellanic Cloud (LMC) 3.6 micron: blue 8.0 micron: green 24 micron: red • One of the nearest galaxies • 50 kpc • Spitzer Space Telescope observations • Spectroscopic survey • Photometric survey 3.6-160 micron • Entire census of AGB stars • C.f. projection problem of the Milky Way Optical image Spitzer image (SAGE) Spitzer Space Telescope The orign and evolution of dust in galaxies

  7. Analysis (1) : selection of dust forming AGB stars Foreground stars AGB stars are the brightest population in mid-infrared AGB stars HII regions / YSOs Distant galaxies Emission line objects (WR stars) Mid-infrared color magnitude diagramme [8.0] vs [3.6]-[8.0] Matsuura et al. (2009, MNRAS 396, 918) The orign and evolution of dust in galaxies

  8. Analysis (2) estimate of gas and dust lost from individual AGB stars • Detailed analysis of 40 AGB stars provides dust/gas mass-loss rate rate (M yr-1) • JHKL photometry • Spitzer spectra (5-35 micron) • Spectral energy distributions are fitted, using radiative transfer code Dust mass-loss rate: 3.1x10-8 M yr-1 Log dM/dt= -6.2/[([3.6]-[8.0])+0.83]-3.39 Evolution of dust in galaxies

  9. Analysis (3) : measured their gas and dust mass-loss rate from IR data Carbon-rich Oxygen-rich AGB stars Detecting dust-embedded AGB stars using Spitzer The orign and evolution of dust in galaxies Matsuura et al. (2009, MNRAS, 396, 918; in preparation)

  10. Gas feedbackin the LMC Type II SNe 2-4x10-2 M yr-1 AGB 2-4x10-2 M yr-1 Evolution of dust in galaxies • Total AGB mass-loss rate: 2-4x10-2 M yr-1 • Oxygen-rich + carbon-rich AGB stars • Type II SNe: 2-4x10-2 M yr-1 • In the LMC, Type II SNe and AGB stars are both important gas sources

  11. Gas budget of the LMC • Star formation rate (SFR) > Gas injection rate from SNe and AGB • LMC star formation depends on the large reservoir of existing ISM gas • The LMC is getting gas poorer. The SFR is likely to be declining with time. • Chemical evolution of the LMC ISM is very slow process (~1 Gyrs) • ISM gas : 8x108Msun (HI + H2) = Gas injection rate (0.03-0.08 Msun yr-1) x 1 Grys • Star formation rate (SFR) > Gas injection rate from SNe and AGB • LMC star formation depends on the large reservoir of existing ISM gas • The LMC is getting gas poorer. The SFR is likely to be declining with time. • Chemical evolution of the LMC ISM is very slow process (~1 Gyrs) • ISM gas : 8x108Msun (HI + H2) = Gas injection rate (0.03-0.08 Msun yr-1) x 1 Grys Star formation rate 0.2-0.3 M yr-1 SNe +AGB 0.03-0.08 M yr-1 ISM gas 8x108 M Evolution of dust in galaxies

  12. Global dust budget in the Large Magellanic Cloud • Missing dust input problem in the LMC! • Current LMC dust mass: 2x106 M • HI+H2 gas mass (8x108 M) x dust-to-gas ratio (0.0025) • (>0.9x106 M; Meixner et al. 2010 from Herschel observations) • Dust injection rate from AGB stars: 5x10-5 M yr-1 (up to 11x10-5 M yr-1) • requires>20 Gyrs Lifetime of the LMC (~15 Gyrs) • Dust lifetime was estimated to be 4-8x108 yrs (Jones et al. 1994) • Dust deficit is short by a factor of 30 SNe Dust formation? (40-80000) M Shock destruction? AGB dust (2-9)x104 M over (4-8)x108 years ISM dust 2x106 M Other dust sources are needed The orign and evolution of dust in galaxies

  13. Solutions for the dust deficit? If dust mass increases in starforming regions Gas-to-dust ratios in ISM < in stars (AGB, SNe) Herschel/ALMA • Lower SN dust destruction rate • Dust from high mass stars • Higher SNII dust production rate • Herschel measured dust mass of 0.075 Msun in Galactic SNR Cas A (Barlow et al. 2010) • Consistent with values used in our LMC study • Dust formation in LBV and WR stars • Unaccounted dust mass in AGB stars? • Dust mass increases in ISM • External dust sources The orign and evolution of dust in galaxies

  14. Origin and quantity • Effects of metallicities • Dust compositions • Dust formation • Implication for the distant galaxies

  15. Dust compositions • Targets • Polycyclic Aromatic Hydrocarbons (PAHs) in post-AGB stars Blocker (1995) The orign and evolution of dust in galaxies

  16. Difference between Galactic and LMC post-AGB stars: unique PAH features PAH templates from Galactic objects (Peeters et al. 2002) Spectral types of the central stars B LMC metallicity ~half of the solar metallicity A New type, D F,G LMC post-AGB stars which do not fit to Galactic PAH templates (type A-C) No Galactic counterparts found so far The orign and evolution of dust in galaxies Matsuura et al. to be submitted

  17. Origin of new type of PAHs Origin of type-D PAHs Quartet (four –H attached to a ring) Mixture of lab data (Hudgins and Sandford 1998a, b) Compact round-shaped PAHs (no quartet) • Origin of different spectral shapes of PAH features in the LMC stars from Galactic counterparts • Different structures of PAHs • - Reason?: Lower density to prevent collisions between PAHs? The orign and evolution of dust in galaxies

  18. Origin and quantity • Effects of metallicities • Dust compositions • Dust formation • Dust in different environment: low-metallicity galaxies • Bridging local group galaxies to high-z galaxies • Implication for the distant galaxies

  19. Can dust be formed at low metallicities?Dust needs (astronomical) metals! • Oxides • Olivines : Mg2xFe(2-2x)SiO4 • Pyroxenes : MgxFe1-xSiO3 • Carbonaceous dust • Graphite : C • Amorphous : C • Polycyclic aromatic hydrocarbons (PAHs) Dust mass : as a function of metallicity of galaxies It has been suggested that it is difficult to form dust grains in stars in low metallicity (Z<0.1 Z) galaxies But … we found unexpected results The orign and evolution of dust in galaxies

  20. The Galaxies of the Local Group Some galaxies have low metallicities Sculptor dwarf spheroidal (dSph) galaxy [Z/H]~-1.33 Fornax dwarf spheroidal galaxy [Z/H]~-1.0 The orign and evolution of dust in galaxies

  21. Spitzer spectra SiC Amorphous Carbon Sculptor dSph galaxy [Z/H]~-1.33 Sloan, Matsuura et al. (2009, Science 323, 353) FornaxdSph galaxy [Z/H]~-1.0 Matsuura et al. (2007, MNRAS 382, 1889) Contrary to expectation, we detected dust at low metallicities The orign and evolution of dust in galaxies

  22. Dust at low metallicity AGB stars • We detected amorphous (+SiC) dust • Carbon atoms synthesized in AGB stars • Dust formation process around stars is affected • not only by the metallicities of the parent galaxies • but also by elements formed inside stars, in particular, carbon • Amorphous carbon, PAHs • Dust grains are formed around the first generation of AGB stars (Our Galaxy) (Fornax and Sculptor dSph galaxies) The orign and evolution of dust in galaxies Matsuura et al. (2005 A&A 434, 691)

  23. Origin and quantity • Effects of metallicities • Dust compositions • Dust formation • Implication for the distant galaxies

  24. Implications for high-z galaxies with dust (Before our study) Galaxies in the Local Group High-z galaxies Dust sources: SNe (>8 Msun) Dust sources: AGB stars + SNe AGB + SNe Assumed to be low metallicity initially z~6.4; ~0.4 Gyrs (e.g. Bertoldi et al. 2003) About solar metallicity 10-15 Gyrs Metallicity Dust can be formed in AGB stars and SNe even at low metallicity AGE Age of AGB stars is much younger than previously thought (starting 50 Myrs; Vassiliadis & Wood 1993) The orign and evolution of dust in galaxies Sloan, Matsuura et al. (2009, Science, 323, 353)

  25. Hi-GALThe HerschelinfraredGalacticPlaneSurvey HerMES Heritage HERschel Inventory of The Agents of Galaxy Evolution: the Magellanic Cloud Survey The orign and evolution of dust in galaxies

  26. Dust grains We found dust grains in many galaxies … But still we don’t know where they are from. The orign and evolution of dust in galaxies

  27. Summary • Low- and intermediate-mass stars are important dust sources • But still found deficit in dust budget in the LMC • Solutions will be tested using Spitzer/Herschel observations • Dust from AGB stars are more carbon-rich, and contain more PAHs at lower metallicity <-> ISM: weak PAHs • High UV radiation in the ISM at low metallicity destroy PAHs • Better constrains of age of dust forming stars required • High-z galaxies • Lower metallicities do not hamper dust formation in AGB stars • Origins of dust in high-z galaxies are still open question. • Dust mass in high-z galaxies may be explained, if both SNe and AGB stars contribute dust formation The orign and evolution of dust in galaxies

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