Question and Answer
Question ID
0043
Language
English
Assigned Member
S. Ogawa
public
Category
resolve analysis
Name
Anwesh Majumder
Institute
University of Waterloo
Question
In my resolve analysis, I have found the Hp fraction to be only 80% in the 1.7-15.0 keV band (see attachments). These branching ratios have been calculated using the resolve notebook that were available for the PV data analysis. Generally, the Hp fraction in clusters have always been above 97% or something. For Hydra center (ObsId: 201070010), this fraction was over 99%. Is there any particular reason with this observation that led to such low Hp fraction? High background maybe?
Answer from
S. Ogawa
Institute
ISAS/JAXA
Answer
This is due to the "anomalous Ls events."
The in-orbit calibration found more Ls events than the ground study expected. These so-called anomalous Ls events likely originate from cosmic-ray particles or instrumental X-rays induced by cosmic rays, rather than from direct X-ray signals from celestial objects.
Since the X-ray count rate from the celestial object is low in this observation, these events cause the relative fraction of Hp events to be lower.
This affects the calculated effective area function and the relative weights of the line-spread functions in different pixels.
Currently, it is recommended to make Resolve RMFs using a custom cleaned event file that has Ls events removed.
For more detailed information, please refer to the official analysis guides:
XRISM ABC Guide: https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/abc_guide/Resolve_Data_Analysis.html#SECTION00932000000000000000
Things to watch out for page (RSL-4: RMF): https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/ttwof/index.html
Status
Accept 2025-06-21
Close 2025-07-09