Three-dimensional Line Transfer Studies of Compact Molecular ISM at - - PowerPoint PPT Presentation
Millimeter and Submillimeter Astronomy at High Angular Resolution(June.8.2009) Three-dimensional Line Transfer Studies of Compact Molecular ISM at the Centers of Active Galaxies -Models meet Observation- Masako YAMADA(ASIAA) K. Wada, K.
“Millimeter and Submillimeter Astronomy at High Angular Resolution”(June.8.2009) Yamada, Wada & Tomisaka 2007 Yamada & Tomisaka 2009 (submitted)
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✦ compact molecular gas at the active center (R<1kpc)
✦ unified model predicts an obscuring torus [AGN] ✦ many molecular lines (CO,HCN,HCO+,CS...)
have been detected in numbers of galaxies
✦ Three(+) reasons for study molecular ISM
✦ molecular gas as star formation site
Large scale structure → (???) → present star formation (GMC, mol.core, YSO)
Environments【Astrochemistry viewpoint】
✦ Do mol. gas in active galaxies have peculiar character compared with normal
galaxies?
✦ AGN v.s. starburst ? which dominates the energy source??
~ 1 p c NGC6764 (DSS:V band)
Yoshida et al.(2006) physical conditions of the “compact” gases probed by mm/submm lines
MY, Wada & Tomisaka(2007) MY & Tomisaka, submitted
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✦
ISM is in general very inhomogeneous & multi-phase in nature
✦
Current mm./submm. obs found “compact cores” at the centers of active galaxies
✦
typical size of a “compact core”~ 500pc - 1kpc : is it really a single entity? NO!!
✦
non-local rad. coupling would take place (e.g. GC)
1kpc
VLT MELIPAL + VIMOS Kohno et al. 2003 PASJ, 55, L1
1 kpc
P.-Y. Hsieh et al., 2008
12CO(2-1) SMA
←CO obs. of NGC 1097 (Seyfert 1)
Composite (red: radio; green: mid-infrared; blue: X-ray) Galactic Center
ex.)
Christopher et al. 2005
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✦
interpreting data sets of Iν in terms
straightforward
✦
line RT can form a toolbox to decipher tangled “riddles” printed in observed line data cube
My dear Watson, circumstance evidence is a very tricky thing... and there is nothing more deceptive than an “obvious fact”.
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✦
Hydrodynamic simulations:
✦
256x256x128grids(→64x64x32 grids)
✦
evolution of rotating gas in gravitational potential of SMBH and halo
✦
radiative cooling and SNe heating feedback are included
✦
20K<T<1000K, nH< 2x106 cm-3 , Δv～50km/s
✦
torus is globally quasi-steady(Wada&Norman)
✦ Radiative Transfer: [ray tracing with long characteristics method]
✦
non-LTE level population up to J=10 for each grid
✦
assume uniform chemical abundance distribution 【to examine chemistry & clumpiness separately】
✦
0.6km/s<vtherm<4.1km/s ⇔ Δvturb~50km/s、 →velocity structure is taken into account by absorption coeff. profile with micro-turbulence
(density)
Wada&Tomisaka, 2005
Vturb=20km/s
Hogerheijde&van der Tak(2000)
φ(ν)dν = 1 ∆vturb 1 √π exp
∆v2
turb
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✦ Intensity distributions look quite alike of similar strength
✦
HCN/HCO+ rotational lines : B(rotational constant) & μ(electric dipole moment) are almost identical for both molecules
✦ HCN(1-0) and HCO+(1-0) lines display clumpy distribution,
reflecting the inhomogeneous structure of AGN mol. torus
✦
Rclump<O(10pc) : Δθ～ 0.1”@D=20Mpc HCN(1-0), θ=0deg(face-on). HCO+(1-0), θ=0deg. y=2x10-9, vturb=20km/s
45deg. 90deg.
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✦
ISM is in general very inhomogeneous
✦
Rclump<O(10pc) : Δθ～ 0.1”@D=20Mpc in
✦
currently substructures in a compact nuclei might be smeared out in a obs. beam...
✦
.. but we can predict and prepare what we could expect in ALMA era
1kpc
VLT MELIPAL + VIMOS Kohno et al. 2003 PASJ, 55, L1
1 kpc
P.-Y. Hsieh et al., 2004
12CO(2-1) SMA
←CO obs. of NGC 1097 (Seyfert 1) ↓simulation (HCN)
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Vr[km/s] Tb[K] HCN(1-0) HCO+(1-0)
✦
Current obs.-> average turbulent bulk veolocity
✦
ALMA-> can find clumps inside
Gaussian ave.profile
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H13CN H12CN
✦
thick lines and thin isotopologue -> a good indicator of clumpiness
✦
ALMA-> can distinguish line profile distributions of HCN & H13CN
✦
statistical studies of mol. clouds even in the centers of distant galaxies as well as dynamics will be available with ALMA
Vr/100 [km sec-1] 2 4 6 8 Tb[K]
(a)
J=1-0
Vr/100 [km sec-1] 0.0 0.5 1.0 1.5 Tb[K]
(b)
J=4-3
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✦ Distributions of NH, integrated intensity, and
✦
good correlation between NH & Intensity, but not with τ0
✦ nonLTE nJ(Tkin, nH) in clumpy torus generates a
dispersion of αν →τ0-NH relation widen as the dispersion of αν(including
negative αν due to pop. inversion)
✦
LVG analysis cannot reasonably reproduce (Tb, NH, τ0)
τ0 - NH Tb - τ0
HCN(1-0), y=2x10-9
Tb - NH
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✦ increment of y(abundance) raises the emission rate (jij=hνij Aij・ni, ni∝y*nH2)
✦
average torus temperature <Tkin>=174K >> T10 ～4.5K
✦
emission from torus stronger than CMB leads to high Tex & weak overshoot
✦ photon trapping(β) : lowers effective ncirt (Tex[thin] is shift to lower nH2)
✦
in our simulation, <τ0>≈O(1) and β≦1 (→ minor effect compared with the former) T=10K, 30K, 100K, 200K, 1,000K(light color lines for low T)
y=10-8 y=10-9 y=10-10
HCN
thin limit Tex
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✦ highly clumpy torus → NH is composed of
1. tenuous gas encompasses the large scale height 2. dense clump + small amount of tenuous ambient Both of 1, 2 are OK
✦ intensity become strong if dense (Λ∝n2)
and/or pop. inversion (@ n～ncrit)
color: intensity, contour: τ0=1 HCN(1-0), y=2*10-9 density ∆τ
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✦
RHCN/HCO+>2 is observed in a number of galaxies, but results of rad. transfer suggest “RHCN/HCO+ =1 ceiling”
✦
In order to obtain RHCN/HCO+~2:
✦ HCN should be much abundant than HCO+
↑↓
✦ XDR/PDR models (yHCN<yHCO+ in XDR)
Imanishi et al. 2004, Kohno et al. 2005
HCN/HCO+ HCN/CO
Yamada, Wada, & Tomisaka, 2007
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✦ Multi-level analysis → way to evaluate precise (Tkin, n)
✦
“high density tracer” is necessary to reveal density structure
✦
Tkin : high-J transition obs. in submm. band is now AVAILABLE
✦ Increasing # of obs. of high-J lines have found variation in R43/10 & possible
chemical abundance variation mol. ν10 νJ,J-1 HCN 88.6GHz 354.5GHz (J=4-3) CO 115.3GHz 345.8GHz(J=3-2)
Papadoupolus, 2007
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✦ average ratio takes a value around 1 ⇔ peak-to-peak ratio >1 ✦ difference between (a)&(b)→clumpiness inside ✦ as y increases, R43/10 decreases below 1 ✦ one-zone analysis suggests R43/10->1 as tau increases ??
face-on edge-on
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✦ Model multi-phase torus with a simple isothermal two-phase ISM
✦
2 phases = (dense clumps + tenuous ambient), & optically thin over a whole region
✦
If we assume optically thin, average line ratio becomes :
✦
in dense clumps : nJ~thermalized in tenuous ambient : n0~1 (balance between
spontaneous decay)
R′
43/10 ≃
ν10 ×
=(A)
G(Tkin, J) ≡
γJ,0
pxpxpxpxpxpx
(A) = ξ43(nH2f4A43)d + (1 − ξ43)(nH2f4A43)t ξ10(nH2f1A10)d + (1 − ξ10)(nH2f1A10)t ≃ ξ44 exp
kBTkin
H2G(Tkin, J = 4)f0)t
ξ(nH2f1A10)d + (1 − ξ)(n2
H2G(Tkin, J = 1)f0)t
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✦ Numerical evaluation of <R43/10> in isothermal two-phase model
✦
If we assume optically thin, average <R43/10>(ξ,Tkin,nave) takes a value from 0 to 64
✦
<R43/10> can become two-value function
✦
η(inhomogeneity index) strongly influence line ratio ⇒
internal density structure should be taken into account for excitation analysis nave =100[cm-3] nave =1000[cm-3] nave =104[cm-3]
200 400 600 800 10001200 Tkin[K] 10-5 10-4 10-3 10-2 10-1
ξ
200 400 600 800 10001200 Tkin[K] 10-5 10-4 10-3 10-2 10-1
ξ
200 400 600 800 10001200 Tkin[K] 10-5 10-4 10-3 10-2 10-1
ξ
16.00 13.33 10.67 8.00 5.33 2.67 0.00 R43/10
nave=102[cm-3] nave=103[cm-3] nave=104[cm-3]
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✦ examine if <R43/10> in two-phase model can
fit isothermal simulation results
✦
isothermal simulation: line transfer calc. w/ Tkin=const. data [density & vel. same as the
✦ <R43/10> in two-phase model can correctly
derive ξ ⇒two-phase modelling captures the density structure effect \
Tkin=350K 220K 150K 75K 35K 15K
0.0 0.2 0.4 0.6 0.8 1.0 1.2 <I43>/<I10>(sim.) 20 40 60 80 θ(deg)
(a) (b)
0.0 0.2 0.4 0.6 0.8 1.0 <I43>/<I10>(func.) 50 100 150 200 250 300 350 Tkin[K]
face-on edge-on
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✦ R43/10 in clumpy torus shows different values from one-zone ISM
☆combination of clumpiness, inhomogeneous Tex & τ0 affects R43/10 ☆volume filling factor of dense clumps may tune R43/10 even without chemical abundance distribution Q: How should we infer physical properties of inhomogeneous ISM by high-J line ratio??? Papadoupolus, 2007 A: Sense of Physics & RT simulation can provide a simple & useful formula!! [in further progress, stay tuned...]
19 2009年6月8日月曜日
✦ “Observational Visualization” (K. Tomisaka)
⇒”Numerical Astronomy” (MY)
✦ Hydrodynamic simulations + Radiative Transfer -> pseudo obs. tool ✦ hydro. (theoretical models) : ρ(x), T(x), v(x), ymol(x) .... ✦ real observation : Iν(θ) ✦ currently we do not pay much
attention to TA⇔Tb, or response
simulation(Wada&Tomi saka2005)
radiation transfer
Members:(phase1)
Omukai, K.Saigo, MY.+..
20 2009年6月8日月曜日
✦ line transfer simulation of YSO outflow ✦ rotation of magnetocentrifugal-force driven
flow appears in velocity channel maps
Yamada, Machida, Inutsuka & Tomisaka, submitted to ApJ
SiO(7-6), 30deg
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SMA ALMA
Y.Kurono & MY, private comm.
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✦ Line transfer simulation as a toolbox to probe ISM
✦
interpretation of current observations & preparation for forthcoming telescopes
✦
3D - more and more realistic than previous studies
✦ Results I : HCN/HCO+ diagnostics
✦
clumpy molecular torus - complicated excitation → ALMA era
✦
interpretation still controversial for AGN/starburst connection
✦ Results II : R43/10 of HCN (dense gas tracer)
✦
multi-phase ISM nature should be taken into account [vol. filling factor⇔beam filling facor]
✦
isothermal 2-phase modelling seems to capture clumpiness effect on high-J line ratio
✦ Future :
✦
easy to apply for pseudo-observations like imaging simulations
23 2009年6月8日月曜日
June.11 poster see also:
Watson, that man! don’t miss him!
http://www.asiaa.sinica.edu.tw/~masako/outflow
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