· 67 August 1987. Hydrogen atom goes to LTE in limit of large electron densities. Many small bugs uncovered as result of careful comparison with Netzer's ION.
· 68 Cambridge, Fall 1987. Development work in progress.
· 69 December 1987. Hydrogen atom goes to LTE in limit of large photon densities. Ferland and Rees (1988).
· 70 September 1988. He II transfer improved. Improved form of escape probabilities with explicit damping constants. H- and improved free-free heating. Many high excitation metal lines transferred. (Rees, Netzer, and Ferland 1989; Ferland and Persson 1989).
· 71 December 1988. Photon array rewritten, now Compton exchange problem is exact for black bodies with temperatures between 2.7 K and 1010 K. He II a radiation pressure included.
· 72 January 1989. Static version, minor bug fixes.
· 73 1989. Major rewrite of helium treatment. Dust changed to two populations, scattering and absorption included. Default radius and thickness increased by ten orders of magnitude. He+ goes to LTE. Development work on getting helium to go to LTE. IR power law for default AGN continuum now SYMBOL 110 \f "Symbol"+2.5 below 100 micron break. No anumm array, all continuum one array. table star. coolr broken up. Helium to LTE for high electron density.
· 74 1990 January. Hydrogen double precision, many bug fixes. 10 tables among the continua. Kurucz (1989) atmospheres. Improved dust treatment, including photoionization and charge.
· 75 1990, JILA visit. Cosmic abundances changed to Grevesse and Anders. Major bug in constant pressure for HII regions, PNs, etc; did not affect BLR. Calculation of ) was incorrect. Molecules at low temperatures. HDEN now n(Ho) + n(H+) + n(H-) + 2n(H2) + 2n(H2+). Improved Rayleigh scattering treatment. Dielectronic recombination for sulfur (guess). Many changes in dust; Orion paper (Baldwin et al. 1990). Subordinate lines changed to Hummer’s K2 function.
· 76 1990, static version from end of JILA visit.
· 77 through Nov. 1990. optimize option added using Bob Carswell's code. Gaunt factor for brems input spectrum. Reflected continuum predicted. Frequency partition adjusted. X-Ray optical depth now at 0.5 keV. Read in table of points from previous calculation. opsav deleted, now single pointer opsv for all opacities. Numerical array to 100 MeV. Hummer La escape destruction prob. tautot arrays now both in and outward directions. Bound Compton included for all ionization levels. Mean ionization arrays rewritten to make sense. Bug in wind velocity fixed, result now exact. C, O outward diffuse fields changed to OTS.
· 78 through May 91. Continuum escape probability formal H-only opacity. H recombination, cooling over wide range of temp. X-Ray optical depth back to 1 keV. abundances no dust no longer changes abundances of depleted elements. OI treatment is now six-level atom. Default table AGN changed. Continuum normalization rewritten. Milne relation for diffuse fields of H, all He. Fe Ka divided into hot and cold. Beams paper (Ferland, Peterson, Horne, et al. 1992) Many high ionization lines included as OTS and outward ionization sources.
· 79 Summer 91. H molecules completed, C, N, O molecules included. Continuum binning changed for Ca, Fe L-shell ionization potentials. Extensive testing.
· 80 July 91, static version .05. Version 80.06 fixed many small problems discovered by several people. New collision strength for [NeV] put in. This static version ended with 80.09, in January of 1993.
· 81 Late 1991. New collision strengths for [NeV] IR lines (10x larger). Also for [CII], [NIII], and [OIV]. Some are 2x larger. Opacity arrays totally rewritten with eye to Opacity Project data. NIII paper (Ferland 1992).
· 82 Early 1992. X-Ray opacity arrays rewritten. Improved pressure convergence. HJBAR now function. Error in cooling due to collisional ionization of H, He. Sodium and nickel added. /TAU/ array broken up. All heavy element opacities converted to table look-up. Revised collision strengths for NIII lines, improved treatment of atom. NLR abundances deleted, ISM put in their place. Summary comments now driven by subroutine. Cap on 911 OTS field. Note on [FeXI] maser (Ferland 1993). Luminosity command separated into luminosity and intensity commands.
· 83 Autumn 1992, Cambridge and CTIO visits. Hydrogen molecule network completed, Ferland, Fabian, and Johnstone (1993). Collision strengths for fine structure lines changed to Blum and Pradhan 1992, Hollenbach and McKee 89; these changed temperatures for cold ISM by factors of 2. Heavy element molecule network as in Hollenbach and McKee 1989. Code works in fully molecular limit. Kevin Volk’s stars (Atlas 91, and Werner models). More accurate treatment of secondary ionization after Voit visit. [OI] lines each include escape prob. Opacities, destruction probabilities, evaluated within all loops, code far more stable, but roughly three times slower. Transferred HeI 2.06 line correctly, after Shields papers.
· 84 1993 Feb 13, Static version following CTIO visit.
· 85 1994, Revisions following Lexington meeting. Outward only now default continuum transport.
· 86 1995, All of first thirty elements are now in code. Photoionization database changed to Dima Verner’s phfit.
· 87 1995 summer, Map now converges electron densities. Negative populations of OI and FeII atoms solved. Dima’s 6k lines included in cooling and radiative acceleration. Total rewrite of nextdr logic. Ionization predictor corrector logic completely rewritten. Dima’s phfit now fitted to all Opacity Project data.
· 88 1995 Fall-winter. Kirk’s extensive grids of BLR models run. March 1996 visit to Tel Aviv to compare results with Hagai. Kirk carefully went over atomic data base. Iron recombination changed to Arnaud and Raymond (1992). Default iron abundance down 33%. Entire line data base revised.
· 89 1995 winter-spring. These were mainly beta versions with no major changes, but many fixes to problems.
· 90 1996 June 17, static version, extensive year of debugging. Ferland et al. (C90) paper.
· 91 1977, preparation of C version.
· 92 1998, sabbatical at CITA, revision and debugging of C version.
· 94 1999 December 24, gold version of C code.
· 96 2003 January, He isoelectronic sequence, CO multilevel molecule, pgrains distributed grains, atomic data update, H2 molecule.
The atom command is now the primary method of changing treatments of H-like, he-like, and molecular species.
The helium isoelectronic sequence has been broken out.
H2, 12CO and 13CO are now multi-level molecules with the full rotation spectrum predicted.
The pgrains treatment of grain physics has been incorporated, allowing fully resolved treatment of grains charging, collisions, and emission. It has been moved into the grains command with the final release. This effort was led by Peter van Hoof.
Two photon emission, and induced two photon emission, is fully treated for the complete H and He iso-electronic sequences.
The large H2 molecule was incorporated by Gargi Shaw.
The CO network was updated by Nick Abel.
The code can now do dynamical flows. This effort was led by Robin Williams and Will Henney.
The ISM oxygen abundance was changed from 5.01e-4 to 3.19e-4 as recommended by Meyers et al. (1987).
The hydrogen and feii commands have been combined into the atom command, which has many options.
The full hydrogenic isoelectronic sequence is now treated with a single model atom and code base. The model atom can have up to 400 levels.
Parameters used in the treatment of the old-style grains have been revised as per the Weingartner & Draine (2000) paper. This makes it possible to resolve the grain size distribution function, solving for grain properties and emission as a function of their size. This is described in van Hoof et al. (2000).
The code is now ANSI 1989 C, making it especially gcc and Linux friendly.
XE "Cloudy:90 vs 84"The abundances command now needs 29 numbers by default. A new command “init” allows a commonly used set of commands to be saved as a single file and used by a variety of scripts.
Versions 86 and before used a modified version of on-the-spot approximation (OTS) for the Lyman continua of hydrogen and helium. This method was numerically stable and gave results in excellent agreement with Van Blerkom and Hummer (1967). This has been changed to outward-only to obtain better agreement with predictions of Pat Harrington’s and Bob Rubin’s codes (Ferland et al. 1995). The OTS code is still in place and will be used if the diffuse OTS command is entered, but outward-only is the default. The two methods result in temperatures at the illuminated face which can differ by as much as several thousand degrees, but the resulting spectra are surprisingly similar.
The model hydrogen atom has been generalized to an arbitrary multi-level atom (Ferguson and Ferland 1996). The hydrogen levels command is used to specify the number of levels to be used. The collision strengths have been changed to Vriens and Smeets (1980) for levels higher than 3, and Callaway (1994) for collisions with 1, 2 and 3.
Predicted infrared line intensities are now correct for all densities and temperatures greater than 103 K. Versions before 89 used a well l-mixed hydrogen atom, and its predictions were not correct for some infrared lines at low densities.
The routine that computes the free-free gaunt factors has been extended to include the full range the code can handle.
The helium ionization balance at low photon and particle densities, and at high particle densities, has always been exact, and this continues to be the case. There was a problem in the helium ion for high radiation densities, in versions 87 and before. The code used three pseudo levels to represent the levels between 7 and 1000, for H, He, and He+. This seemed to work well for the atoms for the cases of high densities, but testing has shown that it did not represent the physics of the high radiation density limit well. The problem is that the pseudo-levels had very large statistical weights, they represented line energies in the far infrared, and had A’s appropriate for lower levels. As a result they had very large induced rates when the photon occupation numbers were large, and this affected populations of lower levels. As a result the atom became too ionized - as much as a factor of two for He+. The following test illustrates this problem:
title helium ionization in high photon density limit
print departure coef
set dr 0
stop zone 1
constant temper 4
hden 11.000
phi(h) 20.750 range 1
stop thickness 11.7
table agn
In versions 88 and later no pseudo levels are used for any hydrogen or helium atom or ion.
The atomic data base, the organization of aspects of the code dealing with storing heavy element ionization, and all the associated routines, have been totally rewritten. The lightest 30 elements are now included. Photoionization data are from Verner et al. (1996), recombination data partially from Verner and Ferland (1996), and roughly 104 lines of the heavy elements have been added (Verner, Verner, and Ferland 1996).
The number of resonance lines has increased by more than an order of magnitude. All resonance lines listed by Verner, Verner, and Ferland (1996) are included. As a result of these many additional lines the cooling function tends to be larger and smoother.
All lines are now fully transferred, and include pumping by the attenuated incident continuum as a general excitation mechanism. Pumping can be a significant contributor to the formation of weak high excitation lines.
The default solar mixture has been changed to Grevesse and Noel (1993). The biggest change is in the iron abundance. Previous versions had used a higher photospheric abundance. The current version is the 1993 suggested meteoritic abundance.
These are counted in a different but equivalent manner. Now the difference between cooling and heating is used, since this is more numerically stable at high radiation densities. This difference has no physical affect on the predictions, but the printed contributors to the total heating and cooling do appear different.
OP data are now used. For the excited state of Mg+ this is nearly ten times smaller than old screened hydrogenic values. This affects the intensity of Mg II l2798 in some BLR calculations.
Figure 17 This figure shows the O+ photoionization cross sections now used, compared to the Reilman and Manson values, and used in version 84 and before.
The Reilman and Manson photoionization cross sections, used before version 87, show a jump in the photoionization cross section at the 2s - 2p edge, and low values above that threshold extending up to the valence electron threshold. Opacity Project cross sections are used in the current version of the code, and these do not show the 2s edge (the OP calculations find that the 2s and 2p electrons are highly correlated). The cross section remains large up to the valence threshold. The difference approaches a factor of two, and this affects high ionization parameter clouds since O+ is the dominant opacity for some energies.
Verner, et al. (1996) comment on all other cases where the photoionization cross sections have changed. There are generally atoms and first ions where Opacity Project data are now available.
In previous versions of the code both luminosity (quantity radiated into 4p sr) and intensity (a surface flux) were specified with the same command. The code decided which was intended by checking the resulting ionization parameter. This method never failed to the best of my knowledge, but, as the code grows more capable of considering ever more extreme cases, there might eventually come a time when it made the wrong decision. All luminosity-intensity commands have now been split up. For instance, the Q(H) command is now two commands, Q(H) (for number of photons radiated into 4p sr) and f(H), for the surface flux. These commands are all discussed in Part I of Hazy.
The biggest difference between the two versions is in the predicted intensity of Mg II l2798. The intensity of this line is now a factor of two stronger in many models. The new version uses L-shell photoabsorption cross sections from Reilman and Manson (1979), and the older version used inner shell cross sections extrapolated from the table in Weisheit (1974). The cross sections differ by a factor of nearly 3, in the sense that Mg now tends to be more neutral, and Mg II stronger. As a result of the increased cooling by l2798 other lines formed in the same region tend to be weaker.
The following may affect certain specific models, but did not result in changes in any of the “standard” test cases.
The treatment of line-continuum fluorescence in the optically thin limit has been much improved, following Ferland (1992). This can affect hydrogen line emission in clouds that are optically thin in the Lyman continuum.
The treatment of molecules has been vastly improved. The code now goes to the fully molecular (H2 and CO) limit, and reproduces the Tielens and Hollenbach (1985a, b) PDR results for Orion.
The elements Na and Ni have been added.
· Time dependent model turned off.