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diff --git a/noao/artdata/doc/gallist.hlp b/noao/artdata/doc/gallist.hlp new file mode 100644 index 00000000..e1f87623 --- /dev/null +++ b/noao/artdata/doc/gallist.hlp @@ -0,0 +1,488 @@ +.help gallist Feb90 noao.artdata +.ih +TASK +gallist -- make an artificial galaxies list +.ih +USAGE +gallist gallist ngals +.ih +PARAMETERS +.ls gallist +The name of the output text file for the x and y coordinates, +magnitudes, profile types, half-flux radii, axial ratios, and position +angles of the artificial galaxies. Output will be appended to this +file if it exists. +.le +.ls ngals = 100 +The number of galaxies in the output galaxies list. +.le +.ls interactive = no +Examine plots and change the parameters of the spatial, luminosity, and +morphology distributions interactively. +.le + + SPATIAL DISTRIBUTION +.ls spatial = "uniform" +Type of spatial distribution for the galaxies. The types are: +.ls uniform +The galaxies are uniformly distributed between \fIxmin\fR, \fIxmax\fR, +\fIymin\fR, and \fIymax\fR. +.le +.ls hubble +The galaxies are distributed around the center of symmetry \fIxcenter\fR and +\fIycenter\fR according to a Hubble density law of core radius +\fIcore_radius\fR and background density \fIbase\fR. +.le +.ls file +The radial density function is contained in the text file \fIsfile\fR. +.le +.le +.ls xmin = 1., xmax = 512., ymin = 1., ymax = 512. +The range of the output coordinates in pixels. +.le +.ls xcenter = INDEF, ycenter = INDEF +The coordinate of the center of symmetry for the "hubble" +and "file" radial density functions. The default is the +midpoint of the coordinate limits. +.le +.ls core_radius = 50 +The core radius of the Hubble density distribution in pixels. +.le +.ls base = 0.0 +The background density relative to the central density of the Hubble +density distribution. +.le +.ls sseed = 2 +The initial value supplied to the random number generator used to +generate the output x and y coordinates. +If a value of "INDEF" is given then the clock +time (integer seconds since 1980) is used as the seed yielding +different random numbers for each execution. +.le + + MAGNITUDE DISTRIBUTION +.ls luminosity = "powlaw" +Type of luminosity distribution for the galaxies. The types are: +.ls uniform +The galaxies are uniformly distributed between \fIminmag\fR and +\fImaxmag\fR. +.le +.ls powlaw +The galaxies are distributed according to a power law with coefficient +\fIpower\fR. +.le +.ls schecter +The galaxies are distributed according to a Schecter luminosity +function with characteristic magnitude \fImstar\fR and power law exponent +\fIalpha\fR between \fIminmag\fR and \fImaxmag\fR. +.le +.ls file +The luminosity function is contained in the text file \fIlfile\fR. +.le +.le +.ls minmag = -7., maxmag = 0. +The range of output relative magnitudes. +.le +.ls mzero = 15. +Magnitude zero point for Schecter luminosity function. +.le +.ls power = 0.6 +Coefficient for the power law magnitude distribution The default value +of 0.6 is the Euclidean value. +.le +.ls alpha = -1.24 +The power law exponent of the Schecter luminosity function. +The default value is that determined by Schecter from nearby galaxies. +.le +.ls mstar = -21.41 +The characteristic magnitude of the Schecter luminosity function. +.le +.ls lseed = 2 +The initial value supplied to the random number generator used to +generate the output magnitudes. +If a value of "INDEF" is given then the clock +time (integer seconds since 1980) is used as the seed yielding +different random numbers for each execution. +.le + + MORPHOLOGY DISTRIBUTION +.ls egalmix = 0.4 +The fraction of the galaxies that are "ellipticals" represented +by a de Vaucouleurs surface brightness law as opposed to "spirals" +represented by an exponential disk surface brightness law. +.le +.ls ar = 0.3 +Minimum elliptical galaxy axial ratio (major/minor ratio). +.le +.ls eradius = 20.0 +The maximum elliptical galaxy half-flux semi-major scale radius. This is +the radius of an elliptical galaxy with magnitude \fIminmag\fR +before a random factor is added. Spiral galaxies and fainter galaxies +are scaled from this value. +.le +.ls sradius = 1.0 +Ratio between half-flux scale radii of spiral and elliptical models at the +same magnitude. For example an elliptical galaxy with magnitude +\fIminmag\fR will have radius \fIeradius\fR while a spiral galaxy +of the same magnitude with have radius \fIsradius\fR * \fIeradius\fR. +.le +.ls absorption = 1.2 +Absorption correction for edge on spirals in magnitudes. +.le +.ls z = 0.05 +Minimum redshift for power law distributed galaxies. This is the +redshift assigned galaxies of magnitude \fIminmag\fR. The redshifts +are assumed proportional to the square root of the apparent luminosity; +i.e the luminosity distance proportional to redshift. The redshift is used +for computing the mean apparent sizes of the galaxies +according to (1+z)**2 / z. +.le + + USER FUNCTIONS +.ls sfile = "" +The name of the input text file containing the sampled spatial radial +density +function, one sample point per line, with the radius and relative probability +in columns one and two respectively. The sample points need not be +uniformly spaced or normalized. +.le +.ls nssample = 100 +The number of points at which the spatial density function is +sampled. If the spatial density function is analytic or approximated +analytically (the "hubble" option) the function is sampled +directly. If the function is read from a file (the "file" option) an +initial smoothing step is performed before sampling. +.le +.ls sorder = 10 +The order of the spline fits used to evaluate the integrated spatial +density function. +.le +.ls lfile = "" +The name of the input text file containing the sampled luminosity +function, one sample point per line, with the magnitude and relative +probability in columns one and two respectively. The sample points need +not be uniformly spaced or normalized. +.le +.ls nlsample = 100 +The number of points at which the luminosity function is +sampled. If the luminosity function is analytic or approximated +analytically (the "uniform", "powlaw" and "schecter" options) the +function is sampled directly. If it is read from a file +(the "file" option) an initial smoothing step is performed before sampling. +.le +.ls lorder = 10 +The order of the spline fits used to evaluate the integrated +luminosity function. +.le + + INTERACTIVE PARAMETERS +.ls rbinsize = 10. +The bin size in pixels of the plotted histogram of the radial density +distribution. +.le +.ls mbinsize = 0.5 +The bin size in magnitudes of the plotted histogram of the luminosity function. +.le +.ls dbinsize = 0.5 +The bin size in pixels of the plotted histogram of the half-power semi-major +axis distribution. +.le +.ls ebinsize = 0.1 +The bin size of the plotted histogram of the axial ratio distribution. +.le +.ls pbinsize = 20. +The bin size in degrees of the plotted histogram of the position angle +distribution. +.le +.ls graphics = stdgraph +The default graphics device. +.le +.ls cursor = "" +The graphics cursor. +.le +.ih +DESCRIPTION +\fBGallist\fR generates a list of x and y coordinates, magnitudes, +morphological types, half-power radii, axial ratios, and position +angles for a sample of \fIngals\fR galaxies based on a user selected +spatial density function \fIspatial\fR and luminosity function +\fIluminosity\fR and writes (appends) the results to the text file +\fIgallist\fR. If the \fIinteractive\fR parameter is "yes" the user can +interactively examine plots of the spatial density function, the +radial density function, the luminosity function, radii, axial ratios, +and position angle distributions and alter the parameters of the task +until a satisfactory artificial field is generated. + +The spatial density function generates x and y values around a center +of symmetry defined by \fIxcenter\fR and \fIycenter\fR within the x and +y limits \fIxmin\fR, \fIxmax\fR, \fIymin\fR and \fIymax\fR according to +the spatial density function specified by \fIspatial\fR. The three +supported spatial density functions are listed below where R is the +radial distance in pixels, P is the relative spatial density, C is a +constant, and f is the best fitting cubic spline function to the spatial +density function R(user), P(user) supplied by the user in the text file +\fIsfile\fR. + +.nf + uniform: P = C + hubble: P = 1.0 / (1 + R / core_radius) ** 2 + base + file: P = f (R(user), P(user)) +.fi + +The Hubble and user spatial density functions are sampled at +\fInssample\fR equally spaced points, and integrated to give the +spatial density probability function at each sampled point. The +integrated probability function is normalized and approximated by a +cubic spline of order \fIsorder\fR. The x and y coordinates are +computed by randomly sampling the integrated probability function until +\fIngals\fR galaxies which satisfy the x and y coordinate limits +\fIxmin\fR, \fIxmax\fR, \fIymin\fR and \fIymax\fR are generated. + +The luminosity function generates relative magnitude values between +\fIminmag\fR and \fImaxmag\fR (before absorption effects are added) +according to the luminosity function specified by \fIluminosity\fR. +The four supported luminosity functions are listed below where M is the +magnitude, P is the relative luminosity function, C is a constant and f +is the best fitting cubic spline function to the luminosity function +M(user), P(user) supplied by the user in the text file \fIlfile\fR. + +.nf + uniform: P = C + powlaw: P = C * 10. ** (power * M) + schecter: P = C * 10. ** (alpha * dM) * exp (-10. ** dM) + file: P = f (M(user), P(user)) + + where dM = 0.4 * (mstar - M + mzero) +.fi + +The uniform distribution is not very physical but may be useful for +testing. The power law distribution is that expected for a homogeneous +and isotropic distribution of galaxies. The default value of 0.6 is +that which can be calculated simply from Euclidean geometry. Observations +of faint galaxies generally show a smaller value. The Schecter +function provides a good approximation to a galaxy cluster when +used in conjunction with the Hubble spatial distribution (though there +is no mass segregation applied). The "best fit" values for the +parameters \fImstar\fR and \fIalpha\fR are taken from the paper by +Schecter (Ap.J 203, 297, 1976). The \fImzero\fR parameter is used +to convert to absolute magnitudes. Note that it is equivalent to +set \fImzero\fR to zero and adjust the characteristic magnitude +to the same relative magnitude scale or to use absolute magnitudes +directly. + +The Schecter and user file distributions are sampled at \fInlsample\fR +equally spaced points, and integrated to give the luminosity +probability function at each sampled point. The probability function is +normalized and approximated by a cubic spline of order \fIlorder\fR. +The magnitudes are computed by randomly sampling the integrated +probability function until \fIngals\fR objects which satisfy the +magnitude limits \fIminmag\fR and \fImaxmag\fR are generated. + +The artificial galaxies have one of two morphological types, +"ellipticals" with a de Vaucouleurs surface brightness law and +"spirals" with an exponential surface brightness law. The fraction +of elliptical galaxies is set by the parameter \fIegalmix\fR. The +position angles of the major axis are distributed uniformly between 0.0 +and 360.0 degrees. The axial ratio (major to minor) of the elliptical +models is allowed to range uniformly between 1 and \fIar\fR +(that is E0 - E7). + +The spiral models have inclinations, i, ranging uniformly between 0 and +90 degrees. The axial ratio is then given by + + a/b = sqrt (sin(i)**2 * .99 + .01) + +which is taken from Holmberg in Galaxies and the Universe (which +references the work of Hubble). Note the axial ratio is limited to +0.1 by this formula. An internal absorption correction is then +made based on the inclination using the relation + + dM = A * (min (10, cosecant (i)) - 1) / 9 + +where is the absorption of an edge on galaxy relative to face on and +the cosecant is limited to 10. Note that this correction changes +allows galaxies with magnitudes less than \fImaxmag\fR and alters +the luminosity function somewhat. Or in other words, the luminosity +function is based on absorption corrected magnitudes. + +The sizes of the galaxy images are scaled from the maximum half-flux +radius of an elliptical galaxy given by the parameter \fIeradius\fR. +This is the radius given to an elliptical galaxy of magnitude +\fIminmag\fR (prior to adding a random factor described below). The +ratio between the half-flux radii of the exponential disk and de +Vaucouleurs models at a given total magnitude is set by the parameter +\fIsradius\fR (note this is a fraction of \fIeradius\fR and not an +actual radius). This allows adjusting the relative surface brightness +of elliptical and spiral models. + +The distribution of sizes is based on the apparent +magnitude of the galaxies. For the power law magnitude distribution +the cosmological redshift factor for angular diameters is used. The +redshift/magnitude relation is assumed to be such that the redshift is +proportional to the luminosity distance (the square root of the +apparent luminosity). Thus, + + +.nf + Z = z * 10. ** (0.2 * (M - minmag)) + Zfactor = ((1+Z)**2 / Z) / ((1+z)**2 / z) + ellipticals: r = eradisus * Zfactor + spirals: r = sradius * eradius * Zfactor +.fi + +where z is the reference redshift at the minimum magnitude, and Z is the +redshift at magnitude M. For very small z the size varies as the +luminosity distance but at larger z the images appear more extended with +lower surface brightness. For very deep simulations a pure luminosity +distance relation gives faint galaxies which are too small and compact +compared to actual observations. + +For the other magnitude distributions, the Schecter cluster function +in particular where all galaxies are at the same distance, the scale radius +obeys the following relation. + +.nf + ellipticals: r = eradius * 10. ** ((minmag - M) / 6) + spirals: r = sradius * eradius * 10. ** ((minmag - M) / 6) +.fi + +This relation gives the size decreasing slightly less rapidly than that +giving a constant surface brightness. This relation is taken from +Holmberg (Galaxies and the Universe). + +A uniform random factor of 50% is added to the sizes computed for +the power law magnitude distribution and 20% for the other distributions. + +The interactive spatial plot shows the positions of the galaxies, the +galaxy type (circles are de Vaucouleurs profiles and other types are +diamonds), and rough size. +.ih +CURSORS +The following interactive keystroke commands are available from within the +GALLIST task. + +.nf + Gallist Keystroke Commands + +? Print options +f Fit one or more of following + Spatial density function (SDF) + Luminosity function (LF) + Distribution of morphological type + Diameter distribution + Roundness distribution + Position angle distribution +x Plot the x-y spatial density function +r Plot the histogram of the radial density function +m Plot the histogram of the luminosity function +d Plot the histogram of the diameter values +e Plot the histogram of the roundness values +p Plot the histogram of the position angle values +: Colon escape commands (see below) +q Exit program +.fi + +The following parameters can be shown or set from within the GALLIST task. + +.nf + Gallist Colon Commands + +:show Show gallist parameters +:ngal [value] Number of galaxies + +:spatial [string] Spatial density function (SDF) (uniform|hubble|file) +:xmin [value] Minimum X value +:xmax [value] Maximum X value +:ymin [value] Minimum Y value +:ymax [value] Maximum Y value +:xcenter [value] X center for SDF +:ycenter [value] Y center for SDF +:core [value] Core radius for Hubble density function +:base [value] Background density for Hubble density function + +:luminosity [string] Luminosity function (LF) + (uniform|powlaw|schecter|file) +:minmag [value] Minimum magnitude +:maxmag [value] Maximum magnitude +:mzero [value] Magnitude zero-point of schecter LF +:power [value] Power law coefficient for powlaw LF +:alpha [value] Schecter parameter +:mstar [value] Characteristic mag for Schecter LF + +:egalmix [value] Elliptical/Spiral galaxy ratio +:ar [value] Minimum elliptical galaxy axial ratio +:eradius [value] Maximum elliptical half flux radius +:sradius [value] Spiral/elliptical radius at same magnitude +:z [value] Minimum redshift +:absorption [value] Absorption correction for spirals + +:lfile [string] Name of the LF file +:sfile [string] Name of the SDF file +:nlsample [value] Number of LF sample points +:lorder [value] Order of spline approximation to the integrated LF +:nssample [value] Number of SDF sample points +:sorder [value] Order of spline approximation to the integrated SDF + +:rbinsize [value] Resolution of radial SDF histogram in pixels +:mbinsize [value] Resolution of magnitude histogram in magnitudes +:dbinsize [value] Resolution of diameter histogram in pixels +:ebinsize [value] Resolution of roundness histogram in pixels +:pbinsize [value] Resolution of position angle histogram in degrees +.fi +.ih +EXAMPLES +1. Create a galaxy cluster with a power law distribution of field galaxies +and stars as background/foreground. + +.nf + ar> gallist galaxies.dat 100 spatial=hubble lum=schecter egal=.8 + ar> gallist galaxies.dat 500 + ar> starlist galaxies.dat 100 + ar> mkobjects galaxies obj=galaxies.dat gain=3 rdnoise=10 poisson+ +.fi + +Note that the objects are appended to the same file. Actually making +the image with \fBmkobjects\fR takes about 5 minutes (2.5 min cpu) on a +SPARCstation 1. + +2. Examine the distributions for a uniform spatial distribution +and power law magnitude distribution using 1000 galaxies without +creating a data file. + +.nf + ar> gallist dev$null 1000 inter+ + ... an x-y plot will appear on the screen + ... type r to examine the radial density function + ... type m to examine the luminosity function + ... type d to examine the half-flux radii distribution + ... type e to examine the axial ratio distribution + ... type = to make a copy of any of the plots + ... type q to quit +.fi +.ih +REVISIONS +.ls GALLIST V2.11+ +The random number seeds can be set from the clock time by using the value +"INDEF" to yield different random numbers for each execution. +.le +.ls GALLIST V2.11 +The default value for the minimum elliptical galaxy axial ratio was +change to 0.3 to cover the range E0-E7 uniformly. +.le +.ih +BUGS +This is a first version and is not intended to produce a full model +of galaxy fields. Some of the relations used are empirical and +simple minded with the aim being to produce reasonably realistic images. + +The spline approximation to the spatial density and luminosity +probability functions can cause wiggles in the output spatial density +and luminosity functions. Users can examine the results interactively +and experiment with the spline order and number of sample points if +they are not satisfied with the results of GALLIST. The default setup +of 10 sample points per spline piece is generally satisfactory for the +spatial density and luminosity functions supplied here. +.ih +SEE ALSO +starlist mkobjects +.endhelp |