Object generator: Galaxies

Similarly to the previous case, a list of galaxies can be generated. The first part of the form is identical to the one for stars. In the second one the user can specify the galaxy parameters.
  • Input Population:
    • Field of view: the size (in arcsec) of the field of view.
    • Objects: the number of objects in the field of view.
    • Brightest mag: the magnitude of the brightest object
    • Faintest mag: the magnitude of the faintest object
  • Distribution of magnitude: the distribution of the object magnitude can be defined as a power law function or a function defined by the user (uploading a txt file).
    • Power law Index: the slope index -α of the power law function expressed as N(x) = x-α that describes the magnitude distribution.
    • User defined Law: a text file containing the values of the magnitude distribution function: the file columns contain the magnitude and the value of the magnitude distribution (number of objects for a given magnitude).
      NOTE: the faintest and brightest magnitude must be encompassed in the minimum and maximum value defined in the user magnitude distribution.
      Here an example of magnitude distribution file GalMagDistrib.txt: 
      
 # GalMagDistrib.txt
 # put comment character #, at the beginning of each comment line
 # Magnitude  Nr of Objects 
 #            
 #
 15.625 6.53
 15.875 4.35
  ... ...
 26.125 290603.29
 26.375 313097.56
  • Spatial distribution in the FoV: Spatial distribution of the simulated objects in the field of view.
    The available options are:
    • Linear gradient: the gradient values along the x-axes (Gx) and y-axes (Gy) are requested.
    • Radial gradient: the required parameters are the radial gradient (Gr), the radius (R) and the center of the distribution (x-y coordinates in arcsec)
    • User defined Law: Spatial object distribution profile defined though a text file with the value of the distribution as function of the x/y-coordinates SpatialDistrib.txt: 
       # SpatialDistrib.txt
 # put comment character #, at the beginning 
 # of each comment line
 # X   Y    
 # 
 0.0009 1 
 0.0025 9.99E-1            
  ... ... 
 469.98 4.07E-7 
 516.28 3.09E-8 
 567.13 0
  • Galaxy Field Generator: The galaxy population is determined by the following parameters:
    • the effective radius (in arcsec)
    • the Sersic index
    • the Ellipticity
    • the position angle PA (in degree)
    All these quantities are thought following a distribution described by a Power Law function with the slope index and the minimum and maximum values.
The CREATE button produces the output table with the sky distribution of the selected objects.
Figure 2 : Example of list of 100 galaxies distributed in the sky FoV ( Right panel ) with the corresponding magnitude distribution histogram ( Left panel ). The file can be downloaded here. This file can be used as ''user file'' in the On sky Object Distribution option of the Object Generator tool.