Changeset 40706 for trunk/doc/release.2015/ps1.analysis/analysis.tex

Timestamp:

May 3, 2019, 10:57:13 AM (7 years ago)

Author:

eugene

Message:

updates to galaxy parameter plots; more text re: galaxy plots

File:

• trunk/doc/release.2015/ps1.analysis/analysis.tex (modified) (6 diffs)

trunk/doc/release.2015/ps1.analysis/analysis.tex

@@ -2633 +2633 @@
 same underlying simulated stellar population was used.  Galaxies are
 injected into the image with positions on a regularly spaced grid with
-separation of 120 pixels.  The galaxies are injected using Exponential
-and DeVaucouleur profiles in separate simulation runs.  The major axis
-values are randomly distributed between 1 and 10 pixels (0.25 - 2.5
-arcseconds) while the aspect ratios are randomly chosen in a range
-from 0.25 to 1.0.  The position angles are set by the sequence in the
-image and allowed to vary from 0 to 180 degrees.  The images are then
-convolved with a PSF model using the \code{PS1_V1} profile ($\kappa =
-0.2$) and noise is added using Poisson statistics for the detected photons.
+separation of 120 pixels.  A total of 1089 galaxies are injected in
+each image, with all galaxies in an image having the same total
+magnitude.  Galaxies were injected for 51 magnitude bins, ranging from
+17.0 to 22.0.  Given the parameters of the image, these values span
+the range from high signal-to-noise ($> 100$) to undetectable (S/N $<
+1$).  Note that we are not attempting to represent a realistic
+astronomical distribution of galaxies, but rather attempting to
+understand our ability to recover galaxies of a certain type, size,
+and shape in a given image.
+
+The galaxies are injected using Exponential and DeVaucouleur profiles
+in separate simulation runs.  The major axis values are randomly
+distributed between 1 and 10 pixels (0.25 - 2.5 arcseconds) while the
+aspect ratios are randomly chosen in a range from 0.25 to 1.0.  The
+position angles are set by the sequence in the image and allowed to
+vary from 0 to 180 degrees.  The images are then convolved with a PSF
+model using the \code{PS1_V1} profile ($\kappa = 0.2$) and noise is
+added using Poisson statistics for the detected photons.
 
 For the figures below, we present results as a function of the (input)
@@ -2665 +2675 @@
 profile galaxies, with a broader light distribution for the same
 effective radius, are less likely to be detected for the same
-magnitude than DeVaucouleur profile galaxies.
+magnitude than DeVaucouleur profile galaxies.  
 
 \begin{figure}[htbp]
@@ -2685 +2695 @@
 \end{figure}
 
+Figures~\ref{fig:exp.params} and \ref{fig:dev.params} demonstrate the
+recovery of galaxy parameters in these simulations for galaxy using
+the Exponential and DeVaucouleur models, respectively.  
+Both figures show the reliability of the measured magnitudes, major
+and minor axis sizes, and ellipticities.  For all recovered
+parameters, the standard deviation of the difference between the
+measured parameter and the truth value is shown for all galaxies as a
+function of magnitude, as well as for subsets in major-axis ranges.
+The mean of the difference, illustrating any biases, is also given
+for all galaxies.  The comparison for the major and minor axis sizes
+are shown as absolute measurements (in pixels) and as a fraction of
+axis in question.
+
+Some overall patterns can be observed.  First, the parameters measured
+for the exponential profile galaxies are consistently more reliable
+than those measured for the DeVaucouleur profiles.  Second, the errors
+in the estimated magnitudes are primarily driven by errors in the size
+measurements: If the sizes are over-estimated, the fluxes are also
+over-estimated.  Finally, the magnitudes and major axes are more
+accurate for the smaller galaxies, but the ellipticities are more
+accurate for the larger galaxies.
+
 \begin{figure*}[htbp]
   \begin{center}
  \includegraphics[width=\hsize,clip]{pics/{galaxy.exp.params}.png}
-  \caption{\label{fig:exp.complete} Parameter recovery for simulated
+  \caption{\label{fig:exp.params} Parameter recovery for simulated
     galaxies with Exponential profiles.  }
   \end{center}
@@ -2696 +2728 @@
   \begin{center}
  \includegraphics[width=\hsize,clip]{pics/{galaxy.dev.params}.png}
-  \caption{\label{fig:dev.complete} Parameter recovery for simulated
-    galaxies with DeVaucouleur profiles.  }
+  \caption{\label{fig:dev.params} Parameter recovery for simulated
+    galaxies with DeVaucouleur profiles.  } 
   \end{center}
 \end{figure*}
@@ -3024 +3056 @@
 \code{PSF_QF_PERFECT} is less than 0.85.
 
-\note{example of using the lensing elements for binaries?}
+% \note{example of using the lensing elements for binaries?}
 
 \section{Difference Image Photometry}
@@ -3071 +3103 @@
 types of sources.  This model is fitted in the same portion of the
 code which performs the unconvolved galaxy model analysis.
+
 % \note{describe the trailed analytical model}.