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WHAT ISM PHASE DOES [CI] EMISSION TRACE?
Alison Crocker ~ Reed College
Molecular cloud
Tielens &
Hollenbach
(1985)
JD Smith, Eric Pellegrini and the Beyond the Peak team
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CAN I USE IT TO TRACE (CO-DARK) H2?
Molecular cloud
Tielens &
Hollenbach
(1985)
Alison Crocker ~ Reed College
JD Smith, Eric Pellegrini and the Beyond the Peak team
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OUTLINE
▸ Motivation/Background
▸ Observations + theory
▸ Beyond the Peak project [CI]
▸ Empirical analysis
▸ Model-based analysis
Glover et al. 2015
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MOTIVATION/BACKGROUND
Glover et al. 2015
[CI] lines come from fine-structure of ground state C:
3P0
3P1
3P2
62.4 K
23.6 K
0 K
E/k:
[CI] (2-1), 809 GHz, 370 μm
[CI] (1-0), 492 GHz, 609 μm
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MOTIVATION/BACKGROUND
Glover et al. 2015
[CI] lines come from fine-structure of ground state C:
3P0
3P1
3P2
62.4 K
23.6 K
0 K
E/k:
[CI] (2-1), 809 GHz, 370 μm
[CI] (1-0), 492 GHz, 609 μm
Relatively low critical densities:
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MOTIVATION/BACKGROUND
Glover et al. 2015
Wolfire, Hollenbach & McKee+ 2010
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MOTIVATION/BACKGROUND
Glover et al. 2015
Wolfire, Hollenbach & McKee+ 2010
Molecular
Cloud
Diffuse medium
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Glover+ 2015
Offner+ 2013
MOTIVATION/BACKGROUND
MORE COMPLICATED…
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MOTIVATION/BACKGROUND
Glover+ 2015
12CO: opacity at high AV
, photodissociation at low AV
13CO: photodissociation at low AV
; good tracer of H2
at AV
= 3-10
[CI]: CO formation at high AV
; good tracer of H2
at AV
= 1.5 - 7
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MOTIVATION/BACKGROUND
log(X12CO
) log(X[CI]
)
-1.91 1.91
0.0 0.64 1.27
-0.64
-1.27
Offner+ 2014
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BEYOND THE PEAK PROJECT
Subsample of 21 galaxies from the Kingfish sample.
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BEYOND THE PEAK PROJECT
Observed with Herschel Space Observatory’s SPIRE
Fourier Transform Spectrograph (FTS)
NGC 1266, Pellegrini et al. 2013
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BEYOND THE PEAK PROJECT
Observed with Herschel Space Observatory’s SPIRE
Fourier Transform Spectrograph (FTS)
In mapping mode!
[CI] (2-1) maps
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BEYOND THE PEAK PROJECT
Observed with Herschel Space Observatory’s SPIRE
Fourier Transform Spectrograph (FTS)
In mapping mode!
[CI] (2-1) maps
11 resolved in at least 2 lines
18 galaxy centers detected in
at least 2 lines
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EMPIRICAL ANALYSIS
Line ratios of interest.
Higher excitation/lower
excitation:
[CI](2-1)/[CI](1-0)
CO(4-3)/[CI](1-0)
CO(7-6)/[CI](2-1)
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EMPIRICAL ANALYSIS
LIRG range
(Israel+ 2015)
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EMPIRICAL ANALYSIS
Radial
Trends
AGN
AGN AGN AGN/SF
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EMPIRICAL ANALYSIS
Radial
Trends
AGN
AGN AGN AGN/SF AGN
AGN AGN AGN
AGN
AGN/SF
SF
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EMPIRICAL ANALYSIS
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EMPIRICAL ANALYSIS
Low-ratio
galaxies
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EMPIRICAL ANALYSIS
30 K
20 K Dust Temperature
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EMPIRICAL ANALYSIS
Radial
Trends
AGN
AGN AGN AGN/SF AGN
AGN AGN AGN
AGN
AGN/SF
SF
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EMPIRICAL ANALYSIS
30 K
20 K Dust Temperature
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EMPIRICAL ANALYSIS
What 12CO line do the [CI] lines best correlate with?
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Glover et al. 2015
CO intensity
[CI](2-1)
intensity
J=1 J=7
J=4
40 K
18 K Dust Temperature
EMPIRICAL ANALYSIS
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Glover et al. 2015
Dust-mass normalized CO intensity
J=1 J=7
40 K
18 K Dust Temperature
J=4
Dust-mass
normalized
[CI](2-1)
intensity
EMPIRICAL ANALYSIS
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Glover et al. 2015
Dust-mass normalized CO intensity
Dust-mass
normalized
[CI](2-1)
intensity
J=1 J=7
40 K
18 K Dust Temperature
J=4
EMPIRICAL ANALYSIS
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Glover et al. 2015
CO intensity
EMPIRICAL ANALYSIS
BtP
Kamenetzky+14
Combined
[CI] (2-1)
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Glover et al. 2015
CO intensity
[CI](2-1)
intensity
J=1 J=7
J=4
EMPIRICAL ANALYSIS
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Glover et al. 2015
CO intensity
[CI](1-0)
intensity
J=1 J=7
J=4
40 K
18 K Dust Temperature
EMPIRICAL ANALYSIS
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Glover et al. 2015
Dust-mass normalized CO intensity
J=1 J=7
40 K
18 K Dust Temperature
J=4
Dust-mass
normalized
[CI](1-0)
intensity
EMPIRICAL ANALYSIS
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Glover et al. 2015
EMPIRICAL ANALYSIS
BtP
Kamenetzky+14
Combined
[CI] (1-0)
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EMPIRICAL
EMPIRICAL ANALYSIS CONCLUSIONS
▸ Flocculent and Barred/Grand design spirals show different
[CI] ratios
▸ Nature of galaxy center does not (alone) determine central
[CI] ratios
▸ [CI](2-1) correlates best with CO(4-3)
▸ Unclear if [CI](1-0) is a good direct tracer of any CO line
EMPIRICAL ANALYSIS
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PDR MODEL
PDR MODEL
▸ Use PDR Toolkit from Pound, Wolfire, Kaufman
▸ Try various combinations of lines
▸ CO, [CI]
▸ [CII], [OI], [CI], FIR
▸ Parameters fit for:
▸ G0,
UV intensity
▸ n, number density
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PDR MODEL
An example fit to a specific region’s lines.
Good fit zone.
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PDR MODEL
An example fit to a specific region’s lines.
Good fit zone.
Ratios using
CO(7-6) are not
well fit.
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PDR MODEL
PDR fit results to CO(2-1), CO(4-3), [CI](1-0), and [CI](2-1):
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PDR MODEL
An example fit to a specific region’s lines.
Good fit zone.
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PDR MODEL
PDR fit results to FIR, [CII], [OI], [CI](1-0), and [CI](2-1):
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PDR MODEL
PDR fit results to FIR, [CII], [OI], [CI](1-0), and [CI](2-1):
PDR fit results to CO(2-1), CO(4-3), [CI](1-0), and [CI](2-1):
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Glover et al. 2015
Simulation by Glover et al. 2015.
PDR MODEL
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Glover et al. 2015
PDR MODEL
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PDR MODEL CONCLUSIONS
▸ Be careful!
▸ Parameters obtained depend on what you link [CI] lines
with
▸ Multiple phases probably exist
▸ Tie of [CI] (2-1) with CO(4-3) indicates at least this [CI] line
linked to more highly excited gas (shocks, SF feedback?)
PDR MODEL