xmm

Analyzing XMM EPIC-pn data

Largely based on the ABC guide for XMM.
Since SAS tasks often take tens of minutes to run (with or without success) Mac users should check this esoteric solution before proceeding … might avoid some frustration.

1. Recreating the PN event file for the observation
2. Filtering the PN event file
3. Pileup correction
4. Phase-resolved Spectroscopy

The source and background regions on the chip are

annular-src_bkg.png

In order to make the appropriate phase-cuts, we note that

nat_fig.png
nat_txt.png

(from Gierlinski et al. 2008)

So here's a "rule" to select a trough

(1) Guess the location of the trough, say $t_{\rm guess}$
(2) Search $(t_{\rm guess} - P/4, t_{\rm guess} + P/4)$ to find the local minimum, which occurs, say at $t_{\rm min}$. The flux at $t_{\rm min}$ is $f_{\rm min}$.
(3) Search for the crest immediately preceding $t_{\rm min}$, say $t_{\rm lo}$. The flux at $t_{\rm lo}$ is $f_{\rm lo}$.
(4) In the interval $(t_{\rm lo}, t_{\rm min})$ linearly interpolate, starting from $t_{\rm min}$ and searching backwards in time to find the time (say $t_-$) when the flux becomes $f_-$, so that

(1)
\begin{align} f_- = f(t_-) = f_{\rm min} + thresh*(f_{\rm lo} - f_{\rm min}) \; ; \; thresh=0.4 \end{align}

(5) Similary search for the crest immediately succeeding $t_{\rm min}$, say $t_{\rm hi}$. The flux at $t_{\rm hi}$ is $f_{\rm hi}$.
(6) In the interval $(t_{\rm min}, t_{\rm hi})$ linearly interpolate, starting from $t_{\rm min}$ and searching forward in time to find the time (say $t_+$) when the flux becomes $f_+$, so that

(2)
\begin{align} f_+ = f(t_+) = f_{\rm min} + thresh*(f_{\rm hi} - f_{\rm min}) \; ; \; thresh=0.4 \end{align}

(7) The "good time interval" for this trough is given by $(t_-, t_+)$.

P2.png

A similar method is used to find the GTI for the crests.

For the boundaries we note that the flux was increasing near $t=0$ and decreasing near $t=t_{\rm max}$. We assume that the flux at 0 or $t_{\rm max}$ were minima, and use this to calculate $t_-$ for the first crest and $t_+$ for the final crest.

Adopting the above set of rules we get the following set of "hi" and "lo" phases.

phase.png
5. Modeling Phase-resolved Spectra

TBD

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