New in C06.02

This page summarizes all major changes and improvements to Cloudy that will be included in the next release. You may also view the HotFixes and KnownProblems pages, or return to the main RevisionHistory page.

C06.02a (2006 March)

The critical density given with the punch lines data command was not correct for multi-level systems, since in those cases the lifetime of the upper level against all collisional routes out must be taken into account. The file gives the "line" critical density, the ratio of the collision to radiative rate for the line transition itself. As a precaution against confusion the punch lines data command will give a critical density of zero for these complex atoms.

All hot fixes are included in this release and all known problems have been corrected. new in C06.02 (2006 February)

Parts 1 and 3 of Hazy and the Quick Start Guide have been revised. These are in the cloudy_gold/docs directory of the ftp site.

The recombination coefficients computed by Badnell and collaborators have been brought into the code. These include both dielectronic and radiative recombination rate coefficients for ions with 11 or fewer electrons before recombination. These have been published in A&A over the past two years - do an ADS search with Badnell as the author, "recombination" in the title, and A&A the journal. These are not now used as the default but are available for testing. The commands set recombination dielectronic Badnell and set recombination radiative Badnell will tell the code to use these rather than the default rates. The predicted quantities can change significantly.

As part of this extension the code now uses, by default, the mean of the Badnell dielectronic recombination rate coefficients as the guess for ions that have no DR data. This affects the temperature of highly-ionized gas. A series of test cases have been added that check the equilibrium temperature for ionization parameters that occur within the Spitzer S-curve stability diagrams. These have names agn_S_u*.in. The simulation has a temperature that is quite different from that given by C05_07 - the difference is due to the changed DR rates.

The H2 column density printed in the main output, along with the column densities of H0 and H+, was the total H column density and so twice the column density of the molecule itself. This was confusing and has been changed to the column density in H2 molecules.

The xi command started to read its parameter, the log of the ionization parameter, at column five. This command only uses two letters so the scan should start at column three. Thanks to Susmita Chakravorty for finding this inconsistency.

Nick Abel added HNC, HCNH+, C3, C3+, C2H, C2H+, C2H2+, C3H, C3H+, and C2H3+ to the chemistry network. This chemistry is designed to produce more realistic C2 and C3 abundances.

The shielding function for molecular hydrogen is now taken from Elwert et al. (2006). Previously the shielding function of Bertoldi & Draine (1996) was assumed when the three-level model was used. The new shielding function is in much better agreement with the results of the large v,J model (Shaw et al. 2005). The shielding function is changed with the set H2 Solomon command, which has three options, "Elwert", the new default, ""BD96" for Bertoldi & Draine (the default in c05.07), and "TH85", from Tielens & Hollenbach (1985), the default before version C96.

The following table lists column densities predicted for Orion's veil, a translucent cloud that lies a few parsecs this side of the Trapezium stars. Abel et al. (2004; 2006) discuss the physical properties of this layer. The simulation pdr_orion_veil in the test suite gives the best-fit parameters for the layer. The following table compares the effects of using the three approximate treatments of the H2 shielding that can be set as options on the set H2 Solomon command - Tielens & Hollenbach (1985; TH85), Bertoldi & Draine (1996; BD96), Elwert et al. (2006; this new version is now the default). It also shows results of the v,J-resolved model (Shaw et al. 2005) which is included with the atom H2 command. The columns give the log of the predicted H2 column densities in the "ground" and "excited" states. TH85 was assumed before version C96 and BD96 was assumed before C06.01. There is a six order of magnitude spread in the H2 column densities.

Approximation log Htot cm-2 log H2g H2*
TH85 21.75 20.89 15.01
BD96 21.61 17.80 15.15
new 21.61 15.21 14.60
v,J resolved - exact 21.61 14.78 14.73

The word "Get" was present in names of several cdXXX routines and was redundant. It has been removed. The following routines are now renamed: cdGetCooling_last -> cdCooling_last; cdGetDepth_depth -> cdDepth_depth; cdGetHeating_last -> cdHeating_last; cdGetnZone -> cdnZone; cdGetTemp_last -> cdTemp_last; cdGetPressure_depth -> cdPressure_depth; cdGetPressure_last-> cdPressure_last;

The new cdB21cm command will return the mean magnetic field weighted with respect to n(H0)/Tspin. This is the quantity measured with 21 cm Zeeman polarization experiments. It assumes a tangled magnetic field.

The cdTemp command will return the mean temperature averaged over simply radius or volume if the ionization stage is zero and the label consists of four spaces.

The set line precision command was added by Ryan Porter. The increases the number of digits in the printed line wavelengths from four to five, and the number of printed columns across the page is reduced from four to three. This makes it easier to find a particular line in a complex spectrum with a large number of lines.

The cdH2_line command has been added to retrieve the intensity and luminosity of any H2 line.

The dielectronic recombination rate coefficients derived by Nigel Badnell and collaborators have been added as an option. These include recombination to one-electron through eleven-electron species. Use the command "set dielectronic recombination Badnell" to use these rate coefficients rather than the older values. The older values have remained the default for the time being.

The dielectronic recombination command has been changed to "set dielectronic recombination".

Atomic data updated for Fe 10. Larger models of Fe 11 & Fe 13 were added with recent Aggarwal & Keenan data.

Kevin Blagrave added a 14-level model of Fe III.

The FeII atom now always uses the large model, described by Verner et al here, but only computes the lowest 16 levels by default. This has no impact on the code's execution time. As a result the "punch FeII column densities" command will report the column densities of these lowest 16 levels without turning on the full FeII model with the "atom FeII" command. The new "punch FeII column densities" command is described below. The simple model of FeII UV and optical emission described Wills et al. here is also included by default. The "atom FeII" command will sets the number of levels in the FeII atom to its largest value, which is quite slow, and disables the Wills et al. FeII model, since it is no longer needed.

Condensation of molecules onto grains - Nick Abel has incorporated the condensation of molecules onto grain surfaces. Currently CO, H2O, and OH condensation are treated. The density of molecules on grains is given as a species with the molecule's usual label, "CO", "H2O", or "OH", followed by "gr". The rates of UV and cosmic ray desorption along with accretion come from Hasegawa, Herbst, & Leung ApJS, 82, 167 (1992); Hasegawa & Herbst MNRAS, 261, 83 (1993). The grain surface chemistry mentioned in these papers are not included, and therefore our modeling of condensation is closer to the work of Bergin, Langer, and Goldsmith ApJ, 441, 222 (1995), who also use the HHL92, HH93 rates. To turn off condensation, use the "no grain molecules" command. If you want to stop the calculation when a certain fraction of oxygen is in the form of molecules frozen out on grain surfaces, use the "stop molecular depletion fraction xxx" command. By default, Cloudy will stop when 99% of the oxygen abundance has condensed out of the gas phase.

The integrated luminosity over arbitrary wavelength ranges of the predicted continuum can now be entered into the emission-line stack. The exact wavelength ranges, called bands, are controlled by the file bands_continuum.dat in the data directory. This file explains more. It is designed to be edited by the user.

Several charge transfer rate coefficients have been updated to recommended values from the ORNL web site.

He - H2 collision rates from the Oak Ridge collaboration are being introduced as an option. See this paper.

The mutual neutralization rate for H- has been updated to Lepp, Stancil & Dalgargo, 2002, J Phys B, 35, R57. This changed the electron density in low ionization gas.

All of the "level2" lines are now included in the photoexcitation rate for the upper level of the split ground term of Boron-sequence atoms. This is typically an additional two dozen FUV lines and results in a larger excited state column densities for continua that extend into the hydrogen-ionizing continuum.

The wavelengths of lines from He-like ions were not accurate. They have now been updated to lab values.

There are two new commands to save information about the large FeII model atom. The punch FeII levels command will output the level energy (wavenumbers) and statistical weight for each level. The punch FeII column density command will give the level energy (wavenumbers), statistical weight, and column density (cm-2). The level energies and statistical weights make it possible to identify individual levels.

The table HM96 command has been expanded to work at any redshift thanks to a data table kindly provided by Francesco Haardt. By default the continuum will include both quasars and galaxies and the command has a keyword "quasar" to consider only quasars. The old version of the command, which only included quasars at a redshift of 2, is accessed with the keyword "old".

The atom H-like Lyman command has been reorganized with more options. The number of extra Lyman lines added on top of the levels included in the populations is changed with the EXTRA keyword. The PUMP keyword has two further options, OFF to disable Lyman Line pumping and SCALE FACTOR to multiply the pump rates by the number on the command line. These last two options are designed to investigate the effects of Lyman absorption or emission lines in the incident stellar continuum.

The no grain-gas collisional energy exchange command has been added to disable the heating-cooling effects of collisions between the gas and grains.

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