X1822
Event-2D Demo



Back to Event-2D Analysis page
1/7/08
dd@space.mit.edu

Source Model using Source-3D

Similar to other exampes, the source is defined by .source'ing the file: x1822_model.sl.

hydra> .source x1822_model  % or x1822_model_wemiss
hydra> s3d_view_comps;  % view the 3D components
hydra> s3d_proj_comps;  % show projection of the colored-components emission
Note that version 1.1.0 or later of source3d.sl is needed to support opaque components used in the model.

A sequence of images at different orbital phases can then be created by .source'ing x1822_movie.sl

hydra> .source x1822_movie
As each image appears it is saved to a file, e.g., xr00.png -to- xr99.png. The movie (linked below) is created with the ImageMagick command:

convert -delay 10  xr*.png  x1822_s3d_movie.mpg

Movie file: x1822_s3d_movie.mpg -- Enjoy!
(music for movie: x1822_music.mp3)

The the model consists of 5 components: 3 are optically-thin x-ray emission components (Central NS corona - green, Disk - red, and a Bulge - orange) and 2 are opaque components (the Companion and a Rim around the disk edge, both shown in blue.)

The 'movie.sl routine also evaluates and saves the visible brightness of the three components (see the file for specifics.) These values are plotted to create a Light Curve of the Model and its individual components (click plot for larger pdf):

For more science details, see papers by Heinz & Nowak, 2001 ; and Cottam et al. 2001.
Also note that resonable spectra are not defined in the 'model.sl file given here; any XSPEC-based spectra models can be assigned easily in place of the default spectrum used in the file.

HETG Data in Event-2D

The data from the Chandra HETG observation, obsid 671, were reprocessed using the "TGCat" scripts to create an evt2 file and associated arfs. The file x1822_data.sl is .source'ed and loads in the following data sets:

hydra> .source x1822_data
  ...
 - Data:                                     e2d_meta[id].;  e2d_data[id].;  e2d_view[id].
  id  Mission-grat-instrument    Date         2D-axes     ignore  prt  m src   events(k)   exp(ks)          target  
   1        CHANDRA-HETG-ACIS  2000.642    TG_LAM,TIME       0     2  -1  1       56.76      39.4         4U 1822-37
   2        CHANDRA-HETG-ACIS  2000.642    TG_LAM,TIME       0     2   1  1       62.38      39.4         4U 1822-37
   3        CHANDRA-HETG-ACIS  2000.642    TG_LAM,TIME       0     1  -1  1       44.20      39.4         4U 1822-37
   4        CHANDRA-HETG-ACIS  2000.642    TG_LAM,TIME       0     1   1  1       40.80      39.4         4U 1822-37
   5        CHANDRA-HETG-ACIS  2000.642    TG_LAM,TIME       0     2  -1  1      204.13     157.8         4U 1822-37
  10        CHANDRA-HETG-ACIS  2000.642            X,Y       0     0   0  1       15.88      39.4         4U 1822-37
> 11        CHANDRA-HETG-ACIS  2000.642    ENERGY,TIME       0     0   0  1       15.88      39.4         4U 1822-37

Note that the two event axes here are Wavelength (TG_LAM) and Time, also dataset 5 is the combination of all 4 of the dispersed data sets. Looking at the combined data as a Wavelength("x")-Time("y") image gives:

hydra> e2d_view_data(5);
/\
|
|

time

- - Wavelength ( 1A to 23A ) - - - >

Looking at the 1-D projection along the Time axis:

hydra> e2d_plot_1d(5,2);

we get the Light Curve: (Click the plot for larger pdf version.)

Indeed, there is some similarity between the data and the model light curves ;-)

Looking at the 1-D projection along the Wavelength axis:

hydra> e2d_plot_1d(5,1);

gives a plot of the counts Spectrum:

Comparing Data and Model Spectra

... Stay tuned for the HETG 2008 GTO observations of X1822 !