Post on 05-Jan-2016
Science with continuum data
ALMA continuum observations:
Physical, chemical properties and evolution of dust, SFR, SED,
circumstellar discs, accretion discs
Effects of dust
Devriendt et al. 99Wavelength
Inte
nsi
ty
Abundance+compositionof dust affect the galaxies’spectral appearance & influence the physical properties (SFR, metallicity,E(B-V))
SED evolution: SFR, reprocessing dust
Tburst=2 Gyr Tburst=0.5 Gyr
The evolution of a galaxy SED
Dwek 2005
HII regions:SN as originof dust
HI regions:later AGBContribution
dust productiondelayedby a few 108 yr
attenuated stellarspectrum
reradiated dustemission
The evolution of dust with metallicity
Dwek 2005
separate contribution from AGB starsto silicate and carbon dust
K-correctionK-correctionSensitivity with 6 antennas
Blain, 04Blain, 04 Griffin, 05Griffin, 05
Flux stays constant
The covering factor of dust in AGNs from the SED
12 14 16 18 20
-2
0
Log
log
F
Opt.-UVX-ray
IR
dust
covering factor YIR-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
SEDs of QSOsSEDs of QSOsand RGsand RGs
ISO+MAMBO+ISO+MAMBO+SCUBASCUBA
SEDs SEDs reflectreflectdust distributiondust distributionaround the heatingaround the heatingsource + nature ofsource + nature ofthe heating sourcethe heating source
Haas et al., 2005Haas et al., 2005
Protostar developmentProtostar development The continuum evolvesas the star evolves
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 projectedseparation of 1700AU
multiple molecular outflows?
SED changes with grain chemical and physical properties
Grain Radius Relation Grain Radius Relation = Q = Qprpr/(/(a)a),a: grain density and radius, Q,a: grain density and radius, Qprpr radiation pressure radiation pressure
Log
[]
Log[a(m)] Models run
Amorphous Silicates
Crystal. Silicates
Amorphous Carbon
Graphite poor
Dust emissivity depends on chemestry and grain size
Graphite rich
Single Grain Size, Single Composition Disk SED
C400
MgFeSiO4
Mg 1.9Fe 0.1SiO4
C1000
Mg0.6Fe0.4SiO3
MgSiO3
Small grainsSmall grains
Intermediate grainsIntermediate grains
Large grainsLarge grains
SEDs depend on chemicalcomposition
SED of a dust diskSED of a dust diskgenerated by an outer generated by an outer beltbeltof planetesimals with of planetesimals with innerinnerplanets is fundamentallyplanets is fundamentallydifferent from that of thedifferent from that of thedisk without planets.disk without planets.
Disc + planet
dust emission from aface-on disc with a planetALMA 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 AUdistance 50pc,total disc mass 10-2 M
orbital radius 5 AUdistance 100pc,total disc mass 10-2 M
Combined beam
Detection of the warm dustin the vicinity of the planetonly for distance 50-100pc
(Wolf & D’Angelo 2005)
Final Disk SED
SED of dust discsin presence of differentplanetary configurations,4 grain chemestry
same particle sizedistribution n(b)db=n0b-q,distance 50pc,total mass 10-10 M
The SED is very sensitive to inclination
[From Van Dishoeck , ARAA 2004]
[Whitney et al. 2004]
Four geometries, ten inclinations
Pole-on edge-on
silicateice
Silicate feature depends ongrain properties and disc geometry
Dust Cycling in GalaxiesGlobal 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 Spectral Energy DistributionEvidence 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 densemolecular gas: lower temperature,larger far-IR emissivity,no small grains
Dust SED/Composition
=> Enhanced VSG abundance factor ~ 5 : shock processing ?
Dust in the Spica HII region