J/A+A/574/A127 Photodissociation with mechanical heating (Kazandjian+, 2015)
Diagnostics of the molecular component of PDRs with mechanical heating.
II: Line intensities and ratios.
Kazandjian M.V., Meijerink R., Pelupessy I., Israel F.P., Spaans M.
<Astron. Astrophys. 574, A127 (2015)>
=2015A&A...574A.127K 2015A&A...574A.127K
ADC_Keywords: Models ; Galaxies, IR ; Interstellar medium ; Molecular clouds
Keywords: galaxies: ISM - photon-dominated region - turbulence -
ISM: molecules - ISM: clouds
Abstract:
CO observations in active galactic nuclei and starbursts reveal high
kinetic temperatures. Those environments are thought to be very
turbulent due to dynamic phenomena, such as outflows and high
supernova rates. We investigate the effect of mechanical heating on
atomic fine-structure and molecular lines and on their ratios. We try
to use those ratios as a diagnostic to constrain the amount of
mechanical heating in an object and also study its significance on
estimating the H2 mass. Equilibrium photodissociation models (PDRs
hereafter) were used to compute the thermal and chemical balance for
the clouds. The equilibria were solved for numerically using the
optimized version of the Leiden PDR-XDR code. Large velocity-gradient
calculations were done as post-processing on the output of the PDR
models using RADEX. High-J CO line ratios are very sensitive to
mechanical heating ({GAMMA}mech hereafter). Emission becomes at least
one order of magnitude brighter in clouds with n∼105cm-3 and a
star formation rate of 1M_☉/yr (corresponding to
{GAMMA}mech=2x10-19erg/cm3/s). The Emission of low-J CO lines is
not as sensitive to {GAMMA}mech, but they do become brighter in
response to {GAMMA}mech. Generally, for all of the lines we
considered, {GAMMA}mech increases excitation temperatures and
decreases the optical depth at the line centre. Hence line ratios are
also effected, strongly in some cases. Ratios involving HCN are a good
diagnostic for {GAMMA}mech , where the HCN(1-0)/CO(1-0) increases from
0.06 to 0.25, and the HCN(1-0)/HCO+ (1-0) increase from 0.15 to 0.5
for amounts of {GAMMA}mech that are equivalent to 5% of the surface
heating rate. Both ratios increase to more than 1 for higher
{GAMMA}mech , as opposed to being much less than unity in pure PDRs.
The first major conclusion is that low-J to high-J intensity ratios
will yield a good estimate of the mechanical heating rate (as opposed
to only low-J ratios). The second one is that the mechanical heating
rate should be taken into account when determining AV or, equivalently,
NH, and consequently the cloud mass. Ignoring {GAMMA}mech will also
lead to large errors in density and radiation field estimates.
Description:
The provided ascii data are files which constrain the emission flux
(in erg/cm2/s) for atomic and molecular lines. These tables can
be used to reproduce all the figures in the paper except figures
1, 2, 3, 6. Each row in the data correspond to one PDR model. The
description of each of the columns in given below.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
crz1-0.dat 383 1956 Models with varying cosmic ray ionization
rate (see Fig. C6 in the appendix of the paper)
gmz.dat 868 17454 Models with varying mechanical heating rate and
metallicities Z/Z☉ = 0.1, 0.5, 1.0, 2.0
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Byte-by-byte Description of file: crz1-0.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- Index [0/1955] Unique index of the model
8- 17 E10.4 cm-3 ngas [1/1.e6] Gas density of the PDR model
19- 28 E10.4 1.6uW/m2 G0 [1/1.e6] FUV incident flux (G1)
30- 39 E10.4 hW/m3 gmech Mechanical heating rate Γmech
(in erg/cm3/s, see paper)
41- 50 E10.4 s-1 CR [5e-16/5e-13] Cosmic ray ionization rate
52- 57 F6.3 Sun Z [1] Metallicity (solar metallicity)
60- 64 F5.1 mag Av [5/30] Visual extinction of the cloud
66- 75 E10.4 mW/m2 HCO+1-0 ?=- Flux of HCO+(1-0) (erg/cm2/s)
77- 86 E10.4 mW/m2 HCO+2-1 ?=- Flux of HCO+(2-1) (erg/cm2/s)
88- 97 E10.4 mW/m2 HCO+3-2 ?=- Flux of HCO+(3-2) (erg/cm2/s)
99-108 E10.4 mW/m2 HCO+4-3 ?=- Flux of HCO+(4-3) (erg/cm2/s)
110-119 E10.4 mW/m2 HCO+5-4 ?=- Flux of HCO+(5-4) (erg/cm2/s)
121-130 E10.4 mW/m2 HCO+6-5 ?=- Flux of HCO+(6-5) (erg/cm2/s)
132-141 E10.4 mW/m2 HCO+7-6 ?=- Flux of HCO+(7-6) (erg/cm2/s)
143-152 E10.4 mW/m2 HCO+8-7 ?=- Flux of HCO+(8-7) (erg/cm2/s)
154-163 E10.4 mW/m2 HCO+9-8 ?=- Flux of HCO+(9-8) (erg/cm2/s)
165-174 E10.4 mW/m2 HCN1-0 ?=- Flux of HCN(1-0) (erg/cm2/s)
176-185 E10.4 mW/m2 HCN2-1 ?=- Flux of HCN(2-1) (erg/cm2/s)
187-196 E10.4 mW/m2 HCN3-2 ?=- Flux of HCN(3-2) (erg/cm2/s)
198-207 E10.4 mW/m2 HCN4-3 ?=- Flux of HCN(4-3) (erg/cm2/s)
209-218 E10.4 mW/m2 HCN5-4 ?=- Flux of HCN(5-4) (erg/cm2/s)
220-229 E10.4 mW/m2 HCN6-5 ?=- Flux of HCN(6-5) (erg/cm2/s)
231-240 E10.4 mW/m2 HCN7-6 ?=- Flux of HCN(7-6) (erg/cm2/s)
242-251 E10.4 mW/m2 HCN8-7 ?=- Flux of HCN(8-7) (erg/cm2/s)
253-262 E10.4 mW/m2 HCN9-8 ?=- Flux of HCN(9-8) (erg/cm2/s)
264-273 E10.4 mW/m2 HNC1-0 ?=- Flux of HNC(1-0) (erg/cm2/s)
275-284 E10.4 mW/m2 HNC2-1 ?=- Flux of HNC(2-1) (erg/cm2/s)
286-295 E10.4 mW/m2 HNC3-2 ?=- Flux of HNC(3-2) (erg/cm2/s)
297-306 E10.4 mW/m2 HNC4-3 ?=- Flux of HNC(4-3) (erg/cm2/s)
308-317 E10.4 mW/m2 HNC5-4 ?=- Flux of HNC(5-4) (erg/cm2/s)
319-328 E10.4 mW/m2 HNC6-5 ?=- Flux of HNC(6-5) (erg/cm2/s)
330-339 E10.4 mW/m2 HNC7-6 ?=- Flux of HNC(7-6) (erg/cm2/s)
341-350 E10.4 mW/m2 HNC8-7 ?=- Flux of HNC(8-7) (erg/cm2/s)
352-361 E10.4 mW/m2 HNC9-8 ?=- Flux of HNC(9-8) (erg/cm2/s)
363-372 E10.4 cm-2 N(CO) ?=- Column density of CO of the PDR
374-383 E10.4 cm-2 N(H2) ?=- Column density of H2 of the PDR
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Byte-by-byte Description of file: gmz.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 F3.1 Sun Z0 [0.1/2.0] Initial metallicity
(0.1, 0.5, 1.0, 2.0)
5- 10 I6 --- Index [0/4400] Unique index of the model
within the initial metallicity Z0
12- 21 E10.4 cm-3 ngas [1/1.e6] Gas density of the PDR model
23- 32 E10.4 1.6uW/m2 G0 [1/1.e6] FUV incident flux (G1)
34- 43 E10.4 hW/m3 gmech Mechanical heating rate Γmech
(in erg/cm3/s, see paper)
45- 51 F7.4 --- alpha [0/1] Mechanical heating rate in terms of the
surface heating (see eq-1 in the paper)
53- 58 F6.3 Sun Z [0.1/2] Metallicity (in solar metallicity)
61- 65 F5.1 mag Av [5/30] Visual extinction of the cloud
67- 76 E10.4 mW/m2 CO1-0 ?=- Flux of CO(1-0) (erg/cm2/s)
77 A1 --- n_CO1-0 [i] i for +∞
78- 87 E10.4 mW/m2 CO2-1 ?=- Flux of CO(2-1) (erg/cm2/s)
89- 98 E10.4 mW/m2 CO3-2 ?=- Flux of CO(3-2) (erg/cm2/s)
100-109 E10.4 mW/m2 CO4-3 ?=- Flux of CO(4-3) (erg/cm2/s)
111-120 E10.4 mW/m2 CO5-4 ?=- Flux of CO(5-4) (erg/cm2/s)
122-131 E10.4 mW/m2 CO6-5 ?=- Flux of CO(6-5) (erg/cm2/s)
133-142 E10.4 mW/m2 CO7-6 ?=- Flux of CO(7-6) (erg/cm2/s)
144-153 E10.4 mW/m2 CO8-7 ?=- Flux of CO(8-7) (erg/cm2/s)
155-164 E10.4 mW/m2 CO9-8 ?=- Flux of CO(9-8) (erg/cm2/s)
166-175 E10.4 mW/m2 CO10-9 ?=- Flux of CO(10-9) (erg/cm2/s)
177-186 E10.4 mW/m2 CO11-10 ?=- Flux of CO(11-10) (erg/cm2/s)
188-197 E10.4 mW/m2 CO12-11 ?=- Flux of CO(12-11) (erg/cm2/s)
199-208 E10.4 mW/m2 CO13-12 ?=- Flux of CO(13-12) (erg/cm2/s)
210-219 E10.4 mW/m2 CO14-13 ?=- Flux of CO(14-13) (erg/cm2/s)
221-230 E10.4 mW/m2 CO15-14 ?=- Flux of CO(15-14) (erg/cm2/s)
232-241 E10.4 mW/m2 CO16-15 ?=- Flux of CO(16-15) (erg/cm2/s)
243-252 E10.4 mW/m2 13CO1-0 ?=- Flux of 13CO(1-0) (erg/cm2/s)
254-263 E10.4 mW/m2 13CO2-1 ?=- Flux of 13CO(2-1) (erg/cm2/s)
265-274 E10.4 mW/m2 13CO3-2 ?=- Flux of 13CO(3-2) (erg/cm2/s)
276-285 E10.4 mW/m2 13CO4-3 ?=- Flux of 13CO(4-3) (erg/cm2/s)
287-296 E10.4 mW/m2 13CO5-4 ?=- Flux of 13CO(5-4) (erg/cm2/s)
298-307 E10.4 mW/m2 13CO6-5 ?=- Flux of 13CO(6-5) (erg/cm2/s)
309-318 E10.4 mW/m2 13CO7-6 ?=- Flux of 13CO(7-6) (erg/cm2/s)
320-329 E10.4 mW/m2 13CO8-7 ?=- Flux of 13CO(8-7) (erg/cm2/s)
331-340 E10.4 mW/m2 13CO9-8 ?=- Flux of 13CO(9-8) (erg/cm2/s)
342-351 E10.4 mW/m2 13CO10-9 ?=- Flux of 13CO(10-9) (erg/cm2/s)
353-362 E10.4 mW/m2 13CO11-10 ?=- Flux of 13CO(11-10) (erg/cm2/s)
364-373 E10.4 mW/m2 13CO12-11 ?=- Flux of 13CO(12-11) (erg/cm2/s)
375-384 E10.4 mW/m2 13CO13-12 ?=- Flux of 13CO(13-12) (erg/cm2/s)
386-395 E10.4 mW/m2 13CO14-13 ?=- Flux of 13CO(14-13) (erg/cm2/s)
397-406 E10.4 mW/m2 13CO15-14 ?=- Flux of 13CO(15-14) (erg/cm2/s)
408-417 E10.4 mW/m2 13CO16-15 ?=- Flux of 13CO(16-15) (erg/cm2/s)
419-428 E10.4 mW/m2 HCO+1-0 ?=- Flux of HCO+(1-0) (erg/cm2/s)
430-439 E10.4 mW/m2 HCO+2-1 ?=- Flux of HCO+(2-1) (erg/cm2/s)
441-450 E10.4 mW/m2 HCO+3-2 ?=- Flux of HCO+(3-2) (erg/cm2/s)
452-461 E10.4 mW/m2 HCO+4-3 ?=- Flux of HCO+(4-3) (erg/cm2/s)
463-472 E10.4 mW/m2 HCO+5-4 ?=- Flux of HCO+(5-4) (erg/cm2/s)
474-483 E10.4 mW/m2 HCO+6-5 ?=- Flux of HCO+(6-5) (erg/cm2/s)
485-494 E10.4 mW/m2 HCO+7-6 ?=- Flux of HCO+(7-6) (erg/cm2/s)
496-505 E10.4 mW/m2 HCO+8-7 ?=- Flux of HCO+(8-7) (erg/cm2/s)
507-516 E10.4 mW/m2 HCO+9-8 ?=- Flux of HCO+(9-8) (erg/cm2/s)
518-527 E10.4 mW/m2 HCN1-0 ?=- Flux of HCN(1-0) (erg/cm2/s)
529-538 E10.4 mW/m2 HCN2-1 ?=- Flux of HCN(2-1) (erg/cm2/s)
540-549 E10.4 mW/m2 HCN3-2 ?=- Flux of HCN(3-2) (erg/cm2/s)
551-560 E10.4 mW/m2 HCN4-3 ?=- Flux of HCN(4-3) (erg/cm2/s)
562-571 E10.4 mW/m2 HCN5-4 ?=- Flux of HCN(5-4) (erg/cm2/s)
573-582 E10.4 mW/m2 HCN6-5 ?=- Flux of HCN(6-5) (erg/cm2/s)
584-593 E10.4 mW/m2 HCN7-6 ?=- Flux of HCN(7-6) (erg/cm2/s)
595-604 E10.4 mW/m2 HCN8-7 ?=- Flux of HCN(8-7) (erg/cm2/s)
606-615 E10.4 mW/m2 HCN9-8 ?=- Flux of HCN(9-8) (erg/cm2/s)
617-626 E10.4 mW/m2 HNC1-0 ?=- Flux of HNC(1-0) (erg/cm2/s)
628-637 E10.4 mW/m2 HNC2-1 ?=- Flux of HNC(2-1) (erg/cm2/s)
639-648 E10.4 mW/m2 HNC3-2 ?=- Flux of HNC(3-2) (erg/cm2/s)
650-659 E10.4 mW/m2 HNC4-3 ?=- Flux of HNC(4-3) (erg/cm2/s)
661-670 E10.4 mW/m2 HNC5-4 ?=- Flux of HNC(5-4) (erg/cm2/s)
672-681 E10.4 mW/m2 HNC6-5 ?=- Flux of HNC(6-5) (erg/cm2/s)
683-692 E10.4 mW/m2 HNC7-6 ?=- Flux of HNC(7-6) (erg/cm2/s)
694-703 E10.4 mW/m2 HNC8-7 ?=- Flux of HNC(8-7) (erg/cm2/s)
705-714 E10.4 mW/m2 HNC9-8 ?=- Flux of HNC(9-8) (erg/cm2/s)
716-725 E10.4 mW/m2 CS1-0 ?=- Flux of CS(1-0) (erg/cm2/s)
727-736 E10.4 mW/m2 CS2-1 ?=- Flux of CS(2-1) (erg/cm2/s)
738-747 E10.4 mW/m2 CS3-2 ?=- Flux of CS(3-2) (erg/cm2/s)
749-758 E10.4 mW/m2 CS4-3 ?=- Flux of CS(4-3) (erg/cm2/s)
760-769 E10.4 mW/m2 CN1-0 ?=- Flux of CN(11/2-01/2) (erg/cm2/s)
771-780 E10.4 mW/m2 CN2-1 ?=- Flux of CN(23/2-13/2) (erg/cm2/s)
782-791 E10.4 mW/m2 C609 ?=- Flux of [CI]609um (erg/cm2/s)
793-802 E10.4 mW/m2 C369 ?=- Flux of [CI]369um (erg/cm2/s)
804-813 E10.4 mW/m2 O63 ?=- Flux of [OI]63um (erg/cm2/s)
815-824 E10.4 mW/m2 C+158 ?=- Flux of [CII]158.3um (erg/cm2/s)
826-835 E10.4 cm-2 N(CO) ?=- Column density of CO of the PDR
837-846 E10.4 cm-2 N(H2) ?=- Column density of H2 of the PDR
848-857 E10.4 mW/m2 HeatTot ?=- Integrated total heating up to the Av
of the model
859-868 E10.4 K Tkin [10/16260]?=- Weighted kinetic temperature
used by Radex to compute the emission
(see paper)
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Global Notes:
Note (G1): the incident FUV flux is measured in "Habing units" (see Habing
1969BAN....20..177H 1969BAN....20..177H), corresponding to 1.6x10-3erg/cm2/s = 1.6µW/m2
Acknowledgements:
Mher Kazandjian,
References:
Kazandjian et al., PaperI, 2012A&A...542A..65K 2012A&A...542A..65K
(End) M. Kazandjian [Leiden Obs., The Netherlands], P. Vannier [CDS] 15-Sep-2014