ALMA Paola FacultyApr07

36 %
64 %
Information about ALMA Paola FacultyApr07

Published on November 13, 2007

Author: Freedom


Science with continuum data:  Science with continuum data ALMA continuum observations: Physical, chemical properties and evolution of dust, SFR, SED, circumstellar discs, accretion discs Effects of dust:  Effects of dust Devriendt et al. 99 Wavelength Intensity Abundance+composition of dust affect the galaxies’ spectral appearance & influence the physical properties (SFR, metallicity,E(B-V)) Slide3:  SED evolution: SFR, reprocessing dust Tburst=2 Gyr Tburst=0.5 Gyr The evolution of a galaxy SED:  The evolution of a galaxy SED Dwek 2005 HII regions: SN as origin of dust HI regions: later AGB Contribution dust production delayed by a few 108 yr attenuated stellar spectrum reradiated dust emission The evolution of dust with metallicity:  The evolution of dust with metallicity Dwek 2005 separate contribution from AGB stars to silicate and carbon dust K-correction:  K-correction Sensitivity with 6 antennas Blain, 04 Griffin, 05 Flux stays constant Slide7:  The covering factor of dust in AGNs from the SED 12 14 16 18 20 -2 0 Log n log n F(n) Opt.-UV X-ray IR dust covering factor Y IR-bump Blue-bump local AGN The FIR measures the IR bump of high-z QSO and Seyfert -> evolution of dust covering factor and obcuration at high-z Slide8:  SEDs of QSOs and RGs ISO+MAMBO+ SCUBA SEDs reflect dust distribution around the heating source + nature of the heating source Haas et al., 2005 Slide9:  Protostar development The continuum evolves as the star evolves High mass star forming regions:  High mass star forming regions ALMA will resolve continuum emission on ~100AU scales in high-mass (50-100 M) star forming regions - are there accretion disks in massive protostars and how do they look like? - to which extent are massive protostellar core fragmented/clustered? - how does high-mass star formation proceed? coalescence of lower mass objects requires extremely dense clustering via disk accretion as is the case for low mass star formation? it seems well documented observationally that the disk accretion scenario plays a major role at least for moderately massive protostars (10-20M).These are rare, distant, and clustered star formation adds to make them difficult to observe with current facilities. IRAS 05358+3543 Protobinary system at projected separation of 1700AU multiple molecular outflows? Slide11:  SED changes with grain chemical and physical properties Slide12:  Grain Radius Relation b = Qpr/(a) ,a: grain density and radius, Qpr radiation pressure Log[b] Log[a(mm)] Models run Amorphous Silicates Crystal. Silicates Amorphous Carbon Graphite poor Dust emissivity depends on chemestry and grain size Graphite rich Slide13:  Single Grain Size, Single Composition Disk SED C400 MgFeSiO4 Mg 1.9Fe 0.1SiO4 C1000 Mg0.6Fe0.4SiO3 MgSiO3 Small grains Intermediate grains Large grains SEDs depend on chemical composition SED of a dust disk generated by an outer belt of planetesimals with inner planets is fundamentally different from that of the disk without planets. Slide14:  Disc + planet dust emission from a face-on disc with a planet ALMA 900GHz simulations Integration time 8 hours; 10 km baselines; 30 degrees phase noise 1 Mjup 0.5 M 5 MJup 2.5 M orbital radius 5 AU distance 50pc, total disc mass 10-2 M orbital radius 5 AU distance 100pc, total disc mass 10-2 M Combined beam Detection of the warm dust in the vicinity of the planet only for distance 50-100pc (Wolf & D’Angelo 2005) Slide15:  Final Disk SED SED of dust discs in presence of different planetary configurations, 4 grain chemestry same particle size distribution n(b)db=n0b-q, distance 50pc, total mass 10-10 M The SED is very sensitive to inclination:  The SED is very sensitive to inclination [From Van Dishoeck , ARAA 2004] [Whitney et al. 2004] Four geometries, ten inclinations Pole-on edge-on silicate ice Silicate feature depends on grain properties and disc geometry Dust Cycling in Galaxies Global cycle and interstellar processing :  Dust Cycling in Galaxies Global cycle and interstellar processing Diffuse ISM Molecular Clouds CNM WNM WIM Star Formation SN 109 yrs a few 107 yrs 3 109 yrs 3 106 yrs Massive stars Low mass stars Giants cloud envelopes dense cores Dust Evolution: Physical Processes:  Dust Evolution: Physical Processes Photo-processing/destruction Amorphization by cosmic rays Grain shattering/sputtering in fast supernovae shocks (WNM, WIM) Grain shattering in turbulent clouds (CNM) Grain coagulation (CNM) Act on time scales shorter than replenishment time by dying stars (a few 109 yrs) Dust Spectral Energy Distribution Evidence for dust evolution => From the diffuse ISM to molecular clouds, PAHs to large grains :  Dust Spectral Energy Distribution Evidence for dust evolution => From the diffuse ISM to molecular clouds, PAHs to large grains Comp. Power Mass PAH 18% 6% VSG 15% 6% BG 67% 88% Variations in PAH abundance in the diffuse ISM and PDRs Enhanced VSG abundance in low density gas (the Spica HII region) Cold dust associated with dense molecular gas: lower temperature, larger far-IR emissivity, no small grains Dust SED/Composition:  Dust SED/Composition => Enhanced VSG abundance factor ~ 5 : shock processing ? Dust in the Spica HII region Enhancing the FIR/mm dust emissivity:  Enhancing the FIR/mm dust emissivity tFIR/NH = Md/NH * 1/rg * <3*Qext/4a> => For a fixed dust to gas ratio (Md/NH ), higher values of tFIR/NH for fluffy grains (lower rg ) and/or higher < Qext/a> (composite grains?) Dwek 1997 carbon silicates composite

Add a comment

Related presentations