Cosmological Source Catalog

SOXS provides the make_cosmological_sources_file() function to generate a set of photons from cosmological halos and store them in a SIMPUT catalog.

First, import our modules:

import matplotlib

matplotlib.rc("font", size=18)
import soxs

Second, define our parameters, including the location within the catalog where we are pointed via the argument cat_center. To aid in picking a location, see the halo map.

exp_time = (200.0, "ks")
fov = 20.0  # in arcmin
sky_center = [30.0, 45.0]  # in degrees
cat_center = [3.1, -1.9]

Now, use make_cosmological_sources_file() to create a SIMPUT catalog made up of photons from the halos. We’ll set a random seed using the prng parameter to make sure we get the same result every time. We will also write the halo properties to an ASCII table for later analysis, using the output_sources parameter:

soxs.make_cosmological_sources_file(
    "my_cat.simput",
    "cosmo",
    exp_time,
    fov,
    sky_center,
    cat_center=cat_center,
    prng=33,
    overwrite=True,
)

soxs : [INFO     ] 2023-09-15 12:52:55,820 Creating photons from cosmological sources.
soxs : [INFO     ] 2023-09-15 12:52:55,821 Loading halo data from catalog: /Users/jzuhone/Source/soxs/soxs/files/halo_catalog.h5
soxs : [INFO     ] 2023-09-15 12:52:55,898 Coordinates of the FOV within the catalog are (3.1, -1.9) deg.
soxs : [INFO     ] 2023-09-15 12:52:55,898 Selecting halos in the FOV.
soxs : [INFO     ] 2023-09-15 12:52:55,902 Number of halos in the field of view: 384

soxs : [INFO     ] 2023-09-15 12:53:06,915 Created 5750617 photons from cosmological sources.
soxs : [INFO     ] 2023-09-15 12:53:07,037 Appending source 'cosmo' to my_cat.simput.

<soxs.simput.SimputCatalog at 0x11ba4fd50>

Next, use the instrument_simulator() to simulate the observation:

soxs.instrument_simulator(
    "my_cat.simput",
    "cosmo_cat_evt.fits",
    exp_time,
    "lynx_hdxi",
    sky_center,
    overwrite=True,
)

soxs : [INFO     ] 2023-09-15 12:53:07,190 Making observation of source in cosmo_cat_evt.fits.
soxs : [INFO     ] 2023-09-15 12:53:07,363 Detecting events from source cosmo.
soxs : [INFO     ] 2023-09-15 12:53:07,364 Applying energy-dependent effective area from xrs_hdxi_3x10.arf.
soxs : [INFO     ] 2023-09-15 12:53:07,550 Pixeling events.
soxs : [INFO     ] 2023-09-15 12:53:07,883 Scattering events with a image-based PSF.
soxs : [INFO     ] 2023-09-15 12:53:08,358 2161156 events were detected from the source.
soxs : [INFO     ] 2023-09-15 12:53:08,482 Scattering energies with RMF xrs_hdxi.rmf.

soxs : [INFO     ] 2023-09-15 12:53:10,869 Adding background events.
soxs : [INFO     ] 2023-09-15 12:53:10,926 Adding in point-source background.
soxs : [INFO     ] 2023-09-15 12:53:19,089 Detecting events from source ptsrc_bkgnd.
soxs : [INFO     ] 2023-09-15 12:53:19,090 Applying energy-dependent effective area from xrs_hdxi_3x10.arf.
soxs : [INFO     ] 2023-09-15 12:53:20,080 Pixeling events.
soxs : [INFO     ] 2023-09-15 12:53:20,768 Scattering events with a image-based PSF.
soxs : [INFO     ] 2023-09-15 12:53:21,630 4975791 events were detected from the source.
soxs : [INFO     ] 2023-09-15 12:53:21,791 Scattering energies with RMF xrs_hdxi.rmf.

soxs : [INFO     ] 2023-09-15 12:53:26,417 Generated 4975791 photons from the point-source background.
soxs : [INFO     ] 2023-09-15 12:53:26,418 Adding in astrophysical foreground.

soxs : [INFO     ] 2023-09-15 12:53:37,564 Adding in instrumental background.
soxs : [INFO     ] 2023-09-15 12:53:39,504 Making 34156972 events from the galactic foreground.
soxs : [INFO     ] 2023-09-15 12:53:39,507 Making 406062 events from the instrumental background.
soxs : [INFO     ] 2023-09-15 12:53:44,669 Writing events to file cosmo_cat_evt.fits.
soxs : [INFO     ] 2023-09-15 12:53:51,716 Observation complete.

We can use the write_image() function in SOXS to bin the events into an image and write them to a file, restricting the energies between 0.7 and 7.0 keV:

soxs.write_image(
    "cosmo_cat_evt.fits", "cosmo_img.fits", emin=0.7, emax=7.0, overwrite=True
)

We can now show the resulting image:

fig, ax = soxs.plot_image(
    "cosmo_img.fits",
    stretch="sqrt",
    cmap="cubehelix",
    vmin=0.0,
    vmax=2.0,
    width=0.33333,
)