Below are canned simulation support files to assess the technical feasibility
of Cycle 2 observation proposals,
which include Redistribution Matrix files (RMFs), Ancillary Response Files (ARFs), and non-X-ray background
(NXB) files.
These files are mainly to simulate a point source placed at the observatory's aim point -
the XRISM's nominal pointing position at the center of the Resolve sensor.
They also include ARF files for uniformly extended sources to evaluate cosmic ray background or other foreground
or background sources.
This file can simulate an extended source as a primary target.
However, extended source analyses often require tailored source regions and/or complicated source mixing evaluation
(cf. POG Chapter 7).
Therefore, we recommend that extended source proposers use HEASoft/HEASim or other event simulators.
For the definitions and usages of RMF, ARF, and NXB files,
please refer to the proposer's observatory guide (POG, html, pdf) or XRISM Community Workshop
presentations.
Resolve Simulation Files
These files assume the followings.
The data are taken from 34 Resolve pixels, excluding pixel 27.
All ARF files are for the closed Gate Valve (GV) condition, conforming to Cycle 2 policies.
This standard RMF with the large (L) type (cf. ABC guide)
assumes that 100% of the events are high-resolution primaries (Hp).
It can be used as is for faint or moderately bright source simulations,
providing a realistic resolution response for each energy bin based on onboard calibration.
Bright source simulations must consider the reduction of Hp events with the grade branching ratio.
This RMF assumes 100% of low-resolution events (Lp), conservatively estimated at 18 eV resolution in all pixels. It should only be used to simulate very bright sources (see POG for more details).
This standard, baseline ARF assumes a point source placed at the center of the detector array (i.e., the aimpoint),
with the filter wheel set on the open position.
It can be used for most science cases.
This ARF assumes a point source at the aimpoint, observed with the neutral (ND) filter.
This filter blocks ~75% of the incoming flux through the sensitive energy band,
ensuring a higher fraction of high-resolution events for very bright sources.
Refer to Section 5.8.1 of the POG for more information.
This ARF assumes a point source at the aimpoint, observed with the beryllium (Be) filter.
This filter attenuates soft X-rays to achieve a higher fraction of high-resolution events for bright sources,
but the effect is limited under the closed GV condition.
Refer to Section 5.8.1 of the POG for more information.
This ARF is for a uniformly extended (flat) source.
It assumes uniform (flat) emission originates within a 5 arcmin radius circle centered at the aimpoint.
Users must adjust the spectral model normalization to match the flux from the r = 5 arcmin encircled area.
This non-X-ray background spectrum is simulated from the model, rsl_nxb_model_v1.mo, described in detail
on the NXB Spectral Models page.
The model is based on the study of XRISM night Earth observations during the commissioning and early PV phases,
and the simulation assumes a 1-billion-second exposure to achieve enough photon statistics for individual spectral bins.
This model assumes Hp event data obtained from 34 detector pixels, excluding pixel 27.
The spectrum can be renormalized for sub-array data with the number ratio of selected pixels over the 34 total pixels.
This model does not include sky X-ray foreground or background components.
Please read the Resolve spectrum simulation instruction
on how to include the NXB and sky background components in your simulation.
Xtend Simulation Files
These files assume the followings.
The data are taken from a region within 2.5 arcmin from the aimpoint,
including ~93% of photons from a primary point source.
The background scaling factor (BACKSCAL) in the NXB file is in the X/Y (SKY) coordinates.
This RMF is for simulating Xtend observations with any publicly available CCD mode
(Full Window, 1/8 Window, 1/8 Window 0.1 s burst).
Note that it is not available for sources above the photon pile-up limit of each mode
(see POG).
This ARF is for a uniformly extended (flat) source spectrum extracted from a 2.5 arcmin radius
encircled region.
The calculation assumes the emission originates within a co-axial 5 arcmin radius circle.
Users must adjust the spectral model normalization to match the flux from the r = 5 arcmin encircled emission region.
This non-X-ray background spectrum is produced from XRISM night Earth observations during the commissioning and early PV phases,
described in detail on the NXB Spectral Models page.
It is extracted from nearly the entire Xtend FOV (360 < DETY <1440, ~1081 arcmin2) with an exposure of 95611 sec,
but it is normalized for a r = 2.5 arcmin circular region by multiplying the exposure time by ~55.1.
Users may renormalize the spectrum to the selected source extraction area.
This file does not include sky background components, which may affect your science case.
Please read the instruction page on how to include the NXB and sky background
components in your simulation.
