Radio User’s Workshop, Daejeon, August 16-17, 2018
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Probing Nanoparticles and Disk Imaging
Spinning Dust Emission: A New Window in Astrophysics
V892 TauNanodiamond
Thiem Hoang (KASI & UST)
Planck Collaboration
Anomalous Microwave Emission (AME) Discovery & Spinning Dust
▪ 1996 Kogut et al. found emission excess at 31 GHz▪ 1997 Leitch et al. found emission excess at 14.5 & 31GHz (AME intro)▪ 1998 Draine & Lazarian proposed spinning dust by very small grain (PAH)
Planck Collaboration 2011, A20
Planck (2011) discovered 4 new AME regions
Spinning dust provides a great fit to AME from Planck
free-free
thermal dustspinning dust
Perseus CloudPlanck Collaboration+2011
5
Planck (2013) discovered 98 clouds with AME
Spinning dust becomes an accepted CMB foreground
6Copyright of Planck Collaboration
Physics of Spinning Dust EmissionRapidly spinningDipole moment
• Electric Dipole: polarity, e.g., polar bonds (C-H, Si-H), asymmetric change distribution on grain surface.
• Grain rotation: gas-grain collisions, UV photons and FIR emission
€
Ped (ω) =23
µ2ω4
c3
Emission Power Rotation Frequency
Spinning Dust Emission Model
PAH
μ
ĴĴ
ω
a1
μ
Hoang, Draine, & Lazarian (2010) Hoang, Lazarian, & Draine (2011) spinning &
wobblinga2
a1θ
μ
Draine & Lazarian (1998)spinning only
Emissivity integrated over size distribution:
€
jνnH
=14π
da 1nHdndaamin
amax∫ 4πω2 fω 2πPed (ω)
Spinning Dust Emission Spectrum
• Peak emissivity increases by a factor ~ 2.• Peak frequency increases by a factor ~1.4 to 1.8.
our result
Hoang, Draine & Lazarian (2010)
Draine & Lazarian (1998)
old
new
a2
a1
Ĵ
θ
μ
a3
Key Developments of Spinning Dust Theory
AME from nanosilicates: Hoang + (2016), Hensley & Draine (2017) AME polarization: Hoang + (2013), Hoang & Lazarian (2016a, 2017)
Dickinson, et al., incl Thiem Hoang (2018, A&A Review)
What are the possible carriers of AME?1. Spinning dust emission:
1. spinning carbonaceous nanoparticles (PAHs; nanodiamonds)
2. spinning silicate nanoparticles (Hoang et al. 2016) 3. spinning iron nanoparticles (Hoang & Lazarian 2016)
2. Magnetic Dipole Emission
NanosilicatePAH molecule Iron Nanoparticle
spinning nanosilicates (Hoang et al. 2016)
free-free
thermal dust
spinning dust
Planck (2011)
spinning PAH (Planck collaboration 2011)
spinning iron nanoparticle (Hoang & Lazarian 2016)
13
Spinning Dust: A New Tool in Astrophysics
• To Probe Cosmic Nanoparticles • To image circumstellar disk and dense cores
Can we use spinning dust to trace nanoparticles in the disk interior?
• Nanoparticles play important roles in disks (e.g., MRI activity, ambipolar diffusion
Why nanoparticles?
• Can trace nanoparticles in any regions (cf. Mid-IR)
Advantages over mid-IR
15 Credit: internet
Current Technique: Tracing PAHs/nanoparticles with Mid-IR Emission
H C
• Mid-IR emsision need UV photons to excite PAHs
16
Mid-IR tracer of PAHs in circumstellar disksIR Emission from disks (Seok & Li 2017)
]
• Strong PAH features detected (Acke + 2004, Habart + 2004)
• 9.7 micron Silicate emission features detected in some disks
• Mid-IR only traces PAHs in the surface layer
Modeling Spinning Dust Emission from Disks
• Observations provide smoking-gun evidence for spinning PAHs and spinning nano silicates
• Spindust trace Nanodust in the entire disk (cf. Mid-IR)
• PAHs/VSG well mixed to the gas due to turbulence (Dullemond + 2005)
• Fragmentation produces PAHs/VSG
• Grain coagulation and dust settling
spinPAH
TE, a
max
=1m
m
Herbig AeBe
spinPAH+TE
101 102Frequency (GHz)
10−1
100
101
102
F ν(mJy)
spinPAH, (a0,σ) = (2A, 0.2)(a0,σ) = (3A, 0.3)(a0,σ) = (4A, 0.4)(a0,σ) = (5A, 0.5)
Spinning Dust Emission from Disks
• Spinning dust dominates over thermal dust at freq < 70 GHz
T-Tauri
spinPAH
TE
spinPAH+TE
101 102
Frequency (GHz)
10−1
100
101
102
F ν(m
Jy)
spinPAH, (a0,σ) = (2A, 0.2)(a0,σ) = (3A, 0.3)(a0,σ) = (4A, 0.4)(a0,σ) = (5A, 0.5)
Bigger PAH
Small PAH
Hoang et al. 2018, ApJ, 862, 116Posted on March 29, ArXiv: 1803.11028
Hoang et al. 2018, ApJ, 862, 116
Spinning Dust successfully reproduce Emission Excess from Herbig Ae/Be Disks
First Detection of AME from Herbig Disks
CMB B-modes
Solar flare,Corona heating
V892 Tau
• AME might not originate from nanodiamond
• Spinning PAHs/Nanosilicates cannot be ruled out
June 12, 2018
Nanodiamond
345 GHz
Toward Disk Imaging at multi wavelengths
How will disks look like in ALMA Band 1 and SKA?
SPHERE (NIR)
ALMA (sub/mm)
Cm Imaging MWC 758 with Spinning Dust
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Simulation from Hoang et al. 2018
22 GHz 33 GHz
60 GHz 80 GHz
• Spinning dust sensitive to Tgas—> can trace gas thermal structure • Intra-cavity may be due to the Tgas dependence of spinning dust
Cavity
345 GHz, ALMA Band 7
Dong et al. (2018)
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0.01044 GHz
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Planck 2013 discovered 98 clouds with AME
Abundance of Nanoparticles Constrained by Planck AME Data
Constraining Abundance of Nanoparticles by Planck AME Data
• PAHs/Nanoparticles decreases with NH
• Dust coagulation occurs in dense regions
Vinh & Hoang (2018, to be submitted)
NH(cm-2)
Nan
o Ab
unda
nce
(%)
25
Summary and Discussion• AME is real, lots of observational evidence for spinning dust• Spinning dust is an accepted emission mechanism in astrophysics• Future radio observations (ALMA Band 1, SKA, ngVLA) should use spinning dust as a tool
• To study nanoparticles in disks and dense regions• Imaging disks and gas temperature probe• Remaining issue: AME polarization and nanoparticle alignment
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Future Perspectives
Dickinson et al. 2017, including T. Hoang
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Spinning dust in star forming regions
31 GHz
Dickinson + 2009
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Spinning dust in star forming complexes W43 W47
Genova-santos et al 2017
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Spinning dust in nearby galaxy NGC 6946
AMI Consortium: Scaife+2010
Murphy+2010
Thank You Very Much!감사합니다!
