Question and Answer

Question ID

0045

Language

English

Assigned Member

S. Ogawa

Category

data products

Name

Mason Leist

Institute

The University of Texas at San Antonio

Question

Q.1
We noticed when examining the RESOLVE data products for Obs ID: 300020010 that we appear to be capturing a spectra below ~2 KeV. It was my understanding that the gate valve was closed and, therefore, we should expect to see no/limited spectra below ~2 KeV. But for this object we are seeing a spectral shape similiar to that found by XMM-Newton (observed 17 Mar. 2001, Obs ID: 0085640101; see figure attached). The RESOLVE data shown in the attached figure was downloaded from the HEASARC data archive, with no additional pipeline reduction steps applied. Is there anyway the RESOLVE spectra observed below ~could be source photons? If not, are there any additional processing steps we could implement to account for the observed flux below ~2 KeV?

Q.2
Thank you very much for the help. I am currently working on building the rmf files for my observation and keep running into the following error:

INFO ::rslrmf: Completed 46000 energy channels out of 60000
INFO ::rslrmf: ERROR: During main: ahfits::Buffer::write() -> 300020010_rsl_Hp_Mp_X_src.rmf[MATRIX] (row 46334): error writing column: N_CHAN [CFITSIO STATUS 412: datatype conversion overflow]
FATAL ::Command failed : returned value 1

My input into the command line was:

rslmkrmf infile=xa300020010rsl_p0px1000_cl2.evt outfileroot=300020010_rsl_Hp_Mp_X_src regmode=DET whichrmf=X resolist=0,1 regionfile=ALLPIX

Just curious if your team has seen this type of error before and what advice you could give to resolve this.

Q.3
Thank you very much for this advice, splitting the matrix seems to work. Out of curiosity, when I run splitrmf=yes, rslmkrmf generates the following 3 rmfs:

_src.rmf
_src_elc.rmf
_src_comb.rmf

As I understand things, I believe the _src.rmf contains the core elements only, the _src_elc.rmf contains the elc components only, and the _src_comb.rmf contains both, is this correct? Which rmf would you recommend I use if I wanted to examine the Resolve spectra?

Answer from

S. Ogawa

Institute

ISAS/JAXA

Answer

A1.
Your Question:
1. Is there anyway the RESOLVE spectra observed below ~2keV could be source photons?
2. If not, are there any additional processing steps we could implement to account for the observed flux below ~2 KeV?

Answer:
1. Almost no source photons are observed below ~2 keV. Your understanding is correct; the gate valve was closed for all XRISM observations, which resulted in a sharp drop in the effective area to effectively zero below ~1.7 keV.
The spectrum you are seeing in this energy range is a combination of two primary effects:
・Non–X-ray background events such as so-called frame events (dominant component).
・Redistributed high-energy photons.

2. Additional screening for crosstalk and frame events is generally recommended.
See the XRISM Data Reduction Guide 6.3:
https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/abc_guide/Resolve_Data_Analysis.html#SECTION00931000000000000000

The XRISM team has developed provisional databases of NXB data for Resolve, along with recipes for extracting NXB spectra and including them in spectral fitting.
https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/nxb/index.html

Redistributed events can be handled through x-large RMF.
See the XRISM Data Reduction Guide 6.5.1 and references therein:
https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/abc_guide/Resolve_Data_Analysis.html#SECTION00951000000000000000

A.2
Processing of rslmkrmf with whichrmf=X may be interrupted due to large RMF data sizes.
A solution is to use the option to split the response function into two matrices, a coarse-grid one for
the ELC, and a fine-grid one for the other components with splitrmf=yes and splitcomb=yes.

See the ABC guide and rslmkrmf help:
https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/abc_guide/Resolve_Data_Analysis.html#SECTION00951000000000000000
https://heasarc.gsfc.nasa.gov/docs/software/lheasoft/help/rslmkrmf.html

Additionally, Pixel 27 at an edge of the array has significantly different gain variation characteristics from the other pixels. Including its data can degrade the spectral energy resolution.

See the ABC guide:
https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/abc_guide/Resolve_Data_Analysis.html#SECTION00934000000000000000
https://heasarc.gsfc.nasa.gov/docs/xrism/analysis/abc_guide/Resolve_Data_Analysis.html#SECTION00951000000000000000

A.3
Yes, your understanding is correct.
We recommend to use _src_comb.rmf to examine the Resolve spectra accurately.

Status

Accept 2025-10-03

Close 2025-11-02