What ISM phase does [CI] emission trace?

Neutral, atomic carbon exists in the interstellar medium between regions where singly-ionized carbon and carbon monoxide lock away the carbon. While it's known this should be in regions where hydrogen is predominantly molecular, it is not known whether the [CI] emission traces mostly a diffuse or dense portion of the molecular gas.

Transcript

1. 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
2. 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
3. OUTLINE ▸ Motivation/Background ▸ Observations + theory ▸ Beyond the Peak project [CI] ▸ Empirical analysis ▸ Model-based analysis Glover et al. 2015
4. 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
5. 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:
6. MOTIVATION/BACKGROUND Glover et al. 2015 Wolfire, Hollenbach & McKee+ 2010
7. MOTIVATION/BACKGROUND Glover et al. 2015 Wolfire, Hollenbach & McKee+ 2010 Molecular Cloud Diffuse medium
8. Glover+ 2015 Offner+ 2013 MOTIVATION/BACKGROUND MORE COMPLICATED…
9. 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
10. MOTIVATION/BACKGROUND log(X12CO ) log(X[CI] ) -1.91 1.91 0.0 0.64 1.27 -0.64 -1.27 Offner+ 2014
11. BEYOND THE PEAK PROJECT Subsample of 21 galaxies from the Kingfish sample.
12. BEYOND THE PEAK PROJECT Observed with Herschel Space Observatory’s SPIRE Fourier Transform Spectrograph (FTS) NGC 1266, Pellegrini et al. 2013
13. BEYOND THE PEAK PROJECT Observed with Herschel Space Observatory’s SPIRE Fourier Transform Spectrograph (FTS) In mapping mode! [CI] (2-1) maps
14. 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
15. 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)
16. EMPIRICAL ANALYSIS LIRG range (Israel+ 2015)
17. EMPIRICAL ANALYSIS Radial Trends AGN AGN AGN AGN/SF
18. EMPIRICAL ANALYSIS Radial Trends AGN AGN AGN AGN/SF AGN AGN AGN AGN AGN AGN/SF SF
19. EMPIRICAL ANALYSIS
20. EMPIRICAL ANALYSIS Low-ratio galaxies
21. EMPIRICAL ANALYSIS 30 K 20 K Dust Temperature
22. EMPIRICAL ANALYSIS Radial Trends AGN AGN AGN AGN/SF AGN AGN AGN AGN AGN AGN/SF SF
23. EMPIRICAL ANALYSIS 30 K 20 K Dust Temperature
24. EMPIRICAL ANALYSIS What 12CO line do the [CI] lines best correlate with?
25. Glover et al. 2015 CO intensity [CI](2-1) intensity J=1 J=7 J=4 40 K 18 K Dust Temperature EMPIRICAL ANALYSIS
26. 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
27. 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
28. Glover et al. 2015 CO intensity EMPIRICAL ANALYSIS BtP Kamenetzky+14 Combined [CI] (2-1)
29. Glover et al. 2015 CO intensity [CI](2-1) intensity J=1 J=7 J=4 EMPIRICAL ANALYSIS
30. Glover et al. 2015 CO intensity [CI](1-0) intensity J=1 J=7 J=4 40 K 18 K Dust Temperature EMPIRICAL ANALYSIS
31. 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
32. Glover et al. 2015 EMPIRICAL ANALYSIS BtP Kamenetzky+14 Combined [CI] (1-0)
33. 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
34. 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
35. PDR MODEL An example fit to a specific region’s lines. Good fit zone.
36. PDR MODEL An example fit to a specific region’s lines. Good fit zone. Ratios using CO(7-6) are not well fit.
37. PDR MODEL PDR fit results to CO(2-1), CO(4-3), [CI](1-0), and [CI](2-1):
38. PDR MODEL An example fit to a specific region’s lines. Good fit zone.
39. PDR MODEL PDR fit results to FIR, [CII], [OI], [CI](1-0), and [CI](2-1):
40. 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):
41. Glover et al. 2015 Simulation by Glover et al. 2015. PDR MODEL
42. Glover et al. 2015 PDR MODEL
43. 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