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XMM-Newton Technical Note
XMM-CCF-REL-261 RGS Background Sp ectra Templates in Wavelength space
R. Gonzґlez-Riestra a April 16, 2010

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CCF comp onents

Name of CCF RGS1 TEMPLATEBCKGND 0006 RGS2 TEMPLATEBCKGND 0007 RGS2 TEMPLATEBCKGND 0008

VALDATE 2001-01-01T00:00:00 2001-01-01T00:00:00 2007-08-17T00:00:00

EVALDATE 2007-08-17T00:00:00

Block X100 X100 X100 X100 X100 X100

s changed P090 1 0.00 P095 2 8.00 P090 1 0.00 P095 2 8.00 P090 1 0.00 P095 2 8.00

L L L L L L

B... B B... B B... B

XSCS flag NO NO NO

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Changes

This release of the RGS TEMPLATEBCKGND CCFs includes the background templates used by the SAS task rgsbkgmodel binned b oth in beta and in wavelength space. It applies to RGS1 and RGS2 and, for the latter, to double- and single-node readout modes (RGS2 TEMPLATEBCKGND 0007 and RGS2 TEMPLATEBCKGND 0008, resp ectively). These CCFs sup ersede previous versions. They are compatible only with rgsbkgmodel version 1.3.3 and higher. The sp ectra used to derive the background templates have b een extracted with version 2.7 of the SAS task rgsspectrum. The procedure followed is detailed in [1] and in the release notes of previous versions ([2], [3] and [4]). The structure of the calibration file has changed with resp ect to previous releases: each file has now 128 extensions, 64 in beta space, and 64 in wavelength space. Within each group, 32 extensions corresp ond to first-order and 32 to second-order background sp ectra. There are different extensions for extraction regions of 90% and 95% in PI. Names of the extensions are coded as follows: Xsss Pppp o r.rr q 1

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RGS 1 0.02
In Beta In Wavelength

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RGS 2 0.02
In Beta In Wavelength

0.015

normalized counts s-1 е-1

normalized counts s-1 е-1 10 20 Wavelength (е) 30

0.01

5в10-3

0

0

5в10-3

0.01

0.015

10

20 Wavelength (е)

30

Figure 1: Comparison of the results of using the background templates binned in beta and in wavelength. The figures show RGS first order background-subtracted sp ectra of the galaxy cluster Ab ell 1413 (RGS 1 on the left and RGS 2 on the right). Sp ectra binned in beta are shown in black, and sp ectra binned in wavelength in red. with sss b eing the size of the extraction region in the cross-disp ersion direction (always 100%), ppp the size of the extraction region in PI (090 or 095), o the order (1 or 2), r.rr the level (from 0.00 to 8.00), and q representing the binning space: 'B' for beta or 'L' for wavelength. For instance, X100 P095 1 0.20 B is the extension containing the first order template background sp ectrum for an extraction region of 95% in PI, and a level of 0.20 cts/sec, binned in b eta space. X100 P095 1 0.20 L is the same template, but in wavelength space.

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Scientific Impact of this Up date

Starting in SAS 10.0, sp ectra generated with rgsspectrum and rgsproc will b e binned in wavelength space by default. With these new CCFs, the user will b e able to apply the background templates in all cases, indep endently of the sp ectral binning chosen.

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Exp ected Up dates

Further up dates might b e made in the future to improve the signal-to-noise ratio of the templates by adding more blank fields and/or to cop e with software up dates.

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Test Pro cedures and Results

The new templates have b een used to generate the model background for a sample of observations that included different levels of background, first and second orders, and 90 and 95% PI extraction regions. The results were satisfactory in all cases. The model background sp ectra binned in wavelength have b een used in XSPEC v12 without any problem. Formal checks:

· The fits viewer fv was used to insp ect the CCF file, their structure and validity dates. Everything was OK: It contains 128 binary extensions, each with five columns: CHANNEL, RATE, QUALITY, BACKSCAL and AREASCAL. · The SAS task cifbuild was run successfully in order to check the ingestion of the files into the calibration index file.

References
[1] "Templates for the RGS Background", R. Gonzalez-Riestra, XMM-SOC-CAL-TN-0058, Octob er ґ 2004 [2] "RGS Background Sp ectra Templates", R. Gonzalez-Riestra, XMM-CCF-REL-217, June 2006 ґ [3] "RGS Background Sp ectra Templates", R. Gonzalez-Riestra, XMM-CCF-REL-229, June 2007 ґ [4] "RGS Background Sp ectra Templates", R. Gonzalez-Riestra, XMM-CCF-REL-250, March 2009 ґ