1. The soft N132D to study the gain of the EPIC-pn camera
María de Juan Ovelar
Trainee XMM-Newton SOC
Tutor: Matteo Guainazzi
ESAC
Summer Alumni Meeting
2009

2. The soft N132D to study the gain of the EPIC camera
Index
Introduction
Sources for calibration
RGS based models
Results
Conclusions and nexts steps
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

3. The soft N132D to study the gain of the EPIC camera
Introduction
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

4. The soft N132D to study the gain of the EPIC camera
1. Introduction
Calibration
1. On ground
2. On flight
Calibration on satellite instruments?
How???
1. Using standard sources
2. Using models of non-standard sources based on more accurate instruments
model quality and accuracy is of high importance when it comes to calibration
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

5. 1. Introduction XMM-Newton X-ray instruments overview
X-ray imaging, moderate resolution spectroscopy, and X-ray photometry
EPIC
(European Photon Imaging Camera)
EPIC MOS
Range: 0.15 – 12 keV
PSF: 5”/14”
Spectral res. : ~ 70 keV
EPIC pn
Range: 0.15 – 15 keV
PSF: 6”/15”
Spectral res. : ~ 80 keV
High-resolution X-ray spectroscopy and spectro-photometry
RGS
(Reflecting Grating Spectrometer)
Range: 0.35 – 2.5 keV
Spectral res. : Å (1st order)
0.025 Å (2nd order)
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

6. Previous calibration campaigns for the EPIC instrument
1. Introduction
Previous calibration campaigns for the EPIC instrument
Models based on EPIC
Images taken from XMM-SOC-CAL-TN (M. Guainazzi, April 2009)
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

7. The soft N132D to study the gain of the EPIC camera
1. Introduction
Project Goal
Build an RGS based model of the spectra of a bright and rich line source and apply it to the EPIC both MOS and pn data
Project guideline
Define a source bright and line rich object
Take X-ray spectra (resolution> EPIC) RGS data
Create an RGS based model as accurate as possible
Compare model with EPIC MOS and pn cameras
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

8. The soft N132D to study the gain of the EPIC camera
2. Sources for calibration
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

9. 2. Sources for calibration
Supernova Remnants
Extended sources
Provide a lot of information (high emitting objects in the X-ray range)
Geometry based operation of RGS
Matter in SNR is moving quite fast!!
This affects the width of the lines in the spectrum and data reduction has to be carried out carefully.
Scheme of the RGS instrument
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

10. 2. Sources for calibration
N132D
Description:
Magellanic Cloud supernova remnant
Center of X-ray emission:
RA=
Dec=
X-ray size (arcmin): 2.1x1.6
Distance: 50kpc
(distance to LMC, Westerlund (1990))
Image from Chandra SNR Catalog
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

11. 2. Sources for calibration
Cassiopea A
Description:
Gallactic supernova remnant (shell like), brightest radio source beyond our solar system
Center of X-ray emission:
RA=
Dec=
X-ray size (arcmin): 5.9x5.5
Distance: 3.4 kpc
(Reed et al., 1995 )
Image from Chandra SNR Catalog
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

12. The soft N132D to study the gain of the EPIC camera
3. RGS based models
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

13. Modelling process: SAS & XSPEC
3. RGS based models
Modelling process: SAS & XSPEC
Extraction of RGS data has been carried out using SAS meta-task rgsproc directly. This led to a few complications later:
rgsproc doesn´t substract the background automatically, so at first both models carried it within
Analysis over the background and spectrum lightcurves of N132D, showed that less than ~8% of the counts actually come from the background
Since Cas A is wider than the RGS aperture (5¨) the background needed to be created from a template
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

14. Modelling process: SAS & XSPEC
3. RGS based models
Modelling process: SAS & XSPEC
2) EPIC data reduced using emproc and then the spectral products were subtracted (background and spectrum from the selected regions in the same CCD, response matrices and ancillary files)
3) XSPEC model build using both Photoelectric Absorption (Wisconsin cross sections) and Bremsstrahlung for the continuum, and as many Gaussian profiles as needed to keep a confidence level of 99% (2.6σ for 3 parameters) using Cash statistics
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

15. Modelling process: SAS & XSPEC
3. RGS based models
Modelling process: SAS & XSPEC
4) Due to the shockwaves inside SNR, the effect of velocity in the emission lines width has to be taken into account.
h(x) : v= 4500 m/s
g(x) : v= 2500 m/s
f(x) : v= 1500 m/s
r(x) : v= 500 m /s
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

16. The soft N132D to study the gain of the EPIC camera
3. RGS based models
N132D
RGS 1&2
Cst =
for 5311 PHA bins
Range: [0.32 – 2.0] keV
Model components:
photon absorption *
bremsstrahlung (0.85 keV)
+ 42 gaussian profiles
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

17. The soft N132D to study the gain of the EPIC camera
3. RGS based models
Cas A
RGS 1&2
Cst =
for 2640 PHA bins
Range: [0.6 – 2.0] keV
Model components:
photon absorption *
bremsstrahlung (1.51 keV)
+ 43 gaussian profiles
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

18. The soft N132D to study the gain of the EPIC camera
4. Results
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

19. The soft N132D to study the gain of the EPIC camera
4. Results
N132D
Excellent agreement!!!
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

20. RGS is missing some X-ray emission!!!
4. Results
Cas A
Cas A is not centered in the EPIC ccd
RGS is missing some X-ray emission!!!
Dispersion direction
Cross-dispersion direction
The model doesn’t fit the EPIC data
Why??
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

21. The soft N132D to study the gain of the EPIC camera
5. Conclusions and next steps
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

22. Ger, Jamie, Leila, Eleonora, Bea!!, Ana, Maël and Cherry
Thanks to…
Matteo Guainazzi
Andy Pollock
Ger, Jamie, Leila, Eleonora, Bea!!, Ana, Maël and Cherry …
and THANK YOU ALL!!!!
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera

23. 5. Conclusions and next steps
RGS accuracy and spectral resolution allows us to significantly improve the models and therefore the whole calibration process of the EPIC instruments
N132D RGS-based model reproduces quite well the EPIC source spectrum directly using rgsproc extended sources around 2.1 arcmin wide can be treated as point-like sources (if they are centered in the RGS ccd!!) in terms of data reduction
Next steps
Correct RGS model for Cas A taking into account the position of the source respect to the RGS instrument
Update cross calibration studies for EPIC with RGS based models for both sources
Summer Alumni Meeting 2009
The soft N132D to study the gain of the EPIC camera