Utilizzo degli archivi e informazioni di base per l’analisi dei dati in banda X

Laboratorio Alte Energie - 2008 1

Utilizzo degli archivi e Utilizzo degli archivi e informazioni di base per informazioni di base per

l’analisi dei dati in banda Xl’analisi dei dati in banda X


1. Le regole di base per la riduzione dei dati in banda X sono essenzialmente le stesse nella maggior parte dei casi, ma una buona conoscenza delle proprieta’ dei satelliti e degli strumenti e’ fondamentale per massimizzare l’output scientifico (e.g., lezioni di P. Grandi e M. Dadina).

Una breve introduzione

2. I dati di ogni satellite X sono in genere “accompagnati” da software o tools specifici atti a facilitarne la riduzione e l’analisi scientifica

3. Come ottenere I dati: proposte di osservazioni dati di proprieta’ (in genere per

un anno) dati in archivio accessibile a tutti gli archivi rappresentano una componente fondamentale

per la ricerca (per esempio, ≈6000 osservazioni nell’archivio Chandra, frutto di 8-9 anni di osservazioni)

Some hints of X-ray data Some hints of X-ray data reductionreduction

Chandra data reduction: from evt1 to NEW evt2 following the CXC threads data reprocessing to adopt the most up-to-date calibrations Chandra: extraction of the source and background spectra for X-ray spectral fitting easy task, background generally not so critical

XMM-Newton data reduction: create NEW pn and MOS1+MOS2 event files and check for high-background intervals following the threads available at vilspa data reprocessing to adopt the most up-to-date calib Extraction of the spectra background typically provides a non-negligible contribution (unless the source is very bright)

Chandra webpageChandra webpage

CXC ScienceCXC ScienceArchiveArchiveProposerProposerCalibrationCalibrationData AnalysisData AnalysisData CentersData Centers[…]

http://chandra.harvard.edu/


ChandraChandra X-ray Data Center (CXC) X-ray Data Center (CXC)

http://chandra.harvard.edu/

Data analysis Data analysis CIAO CIAO Science threads Science threadshttp://cxc.harvard.edu/ciao/threads/index.html

• Introduction Introduction • Data preparationData preparation• Timing analysisTiming analysis• ImagingImaging• Imaging spectroscopyImaging spectroscopy• Grating spectroscopyGrating spectroscopy• […][…]

But … where can we download the data? But … where can we download the data?

http://cxc.harvard.edu/ciao/threads/index.html


ChandraChandra archive: archive: using webchaserusing webchaser

Data archiveData archiveChandra archive: downloading the data with webchaser

primary files with primary files with evt2evt2, images and other stuff, images and other stuff

secondary files with secondary files with evt1evt1, bias, calib. and other stuff, bias, calib. and other stuff

http://cda.harvard.edu/chaser/mainEntry.do

http://cda.harvard.edu/chaser/mainEntry.do


ACIS data preparation: hintsACIS data preparation: hints

I.I. Create a new bad pixel file (Create a new bad pixel file (acis_run_hotpixacis_run_hotpix) to provide a list of) to provide a list of bad and hot pixelsbad and hot pixels

II.II. Create a new EVT2 file for scientific use (Create a new EVT2 file for scientific use (acis_process_eventsacis_process_events)) apply an ACIS gain mapapply an ACIS gain map apply a time-dependent ACIS gain correctionapply a time-dependent ACIS gain correction apply the ACIS CTI correctionapply the ACIS CTI correction apply/remove PHA randomizationapply/remove PHA randomization clean ACIS background in VFAINT mode clean ACIS background in VFAINT mode

III.III. Select the grades and the Good Time Interval (GTI)Select the grades and the Good Time Interval (GTI)

IV.IV. Improve the astrometry of the data (also before acis_process_events) Improve the astrometry of the data (also before acis_process_events) to correct for any known processing offset or to match data with higher to correct for any known processing offset or to match data with higher accuracy positions (e.g., from the radio band)accuracy positions (e.g., from the radio band)

V.V. Filtering the data: check for flares in a background-only region (updatedFiltering the data: check for flares in a background-only region (updated GTI) and select the energy rangeGTI) and select the energy range


evt1 evt1

evt2 evt2


Extraction of spectra in Extraction of spectra in ChandraChandra ACISACIS

i.i. From the “clean” evt2 file, create an image in the chosen energy range From the “clean” evt2 file, create an image in the chosen energy range and determine the centroid of the X-ray emission for spectra extraction and determine the centroid of the X-ray emission for spectra extraction (for either faint or extended sources, visualize also the smoothed image)(for either faint or extended sources, visualize also the smoothed image) Example: Example: dmstatdmstat "evt2_clean1.fits.gz[sky=region(sou_r2.reg)][bin sky=1] "evt2_clean1.fits.gz[sky=region(sou_r2.reg)][bin sky=1] [cols chipx,chipy,ccd_id,x,y]" centroid=yes[cols chipx,chipy,ccd_id,x,y]" centroid=yes

ii.ii. Select the source and background regions using ds9Select the source and background regions using ds9 Avoid to include nearby sources in the background regionAvoid to include nearby sources in the background region

iii.iii. Run Run psextract psextract to extract the (source+background) spectrum, the backg. to extract the (source+background) spectrum, the backg. spectrum, the Redistribution Matrix File (RMF) and the Ancillary spectrum, the Redistribution Matrix File (RMF) and the Ancillary Response File (ARF), required for X-ray spectral analysis within XSPEC Response File (ARF), required for X-ray spectral analysis within XSPEC or Sherpaor Sherpa iv.iv. Rebin the data if the number of counts is high enough to apply the Rebin the data if the number of counts is high enough to apply the 22 statisticsstatistics

RMF and ARF

RMFRMF: includes information on the detector gain and energy resolution (channel energy conversion)

ARFARF: includes information on the effective area, filter transmission and any additional energy-dependent efficiencies

RMFRMF ARFARF


RMFRMF ARFARF


unsmoothed Chandra mosaic


red=0.5-1.5 keV

green=1.5-2.5 keV

blue=2.5-8.0 keV

“true-color” smoothed Chandra mosaic


Example of src+bkg and bkg extraction Example of src+bkg and bkg extraction

XMM-NewtonXMM-Newton webpage webpage

NewsNewsObservers InfoObservers InfoProposers InfoProposers InfoCalibration and Background TreatmentCalibration and Background TreatmentData ProductsData ProductsData AnalysisData Analysis[…]

http://xmm.esac.esa.int/

http://xmm.esac.esa.int/


XMM-XMM-NewtonNewton Science Operation Science Operation CenterCenter

http://xmm.vilspa.esa.es/

Proposer’s Info and Manuals Proposer’s Info and Manuals Instrument info and Instrument info and guides (ABC guide: guides (ABC guide: htpp://heasarc.gsfc.nasa.gov/docs/xmm/abc))Science threads at Science threads at http://xmm.esac.esa.int/sas/7.0.0/documentation/threads

• SASSAS start-up: configuration of the working environment and CCF start-up: configuration of the working environment and CCF (Current Calibration Files)(Current Calibration Files)• EPIC calibrated and concatenated event listsEPIC calibrated and concatenated event lists• RGS: high-resolution spectroscopyRGS: high-resolution spectroscopy• OM: UV photometryOM: UV photometry• […][…]

… … how to retrieve the data to be processed …how to retrieve the data to be processed …

http://heasarc.gsfc.nasa.gov/docs/xmm/abc









http://xmm.esac.esa.int/sas/7.0.0/documentation/threads


XMM-XMM-NewtonNewton archive: archive: using XSAusing XSA

Data archiveData archiveXMM-Newton archive: downloading the data using XSA

ODF ODF (Observation Data Files), useful to use the most up-to-date(Observation Data Files), useful to use the most up-to-date calibrations related to the instruments in the data reprocessing calibrations related to the instruments in the data reprocessing

PPSPPS (Processing Pipeline Files), i.e., already processed data (Processing Pipeline Files), i.e., already processed data using a standard pipelineusing a standard pipeline

http://xmm.esac.esa.int/xsa


EPIC data preparation: hintsEPIC data preparation: hintsI.I. Create a new event file for pn, MOS1, and MOS2 (Create a new event file for pn, MOS1, and MOS2 (epprocepproc and and emprocemproc) )

II.II. Create a light curve to check for flares. Create a light curve to check for flares. Suggestion: select the energy interval E>12 keVSuggestion: select the energy interval E>12 keV

III.III. Remove the period of high background level: Remove the period of high background level: by hand: manually select the new GTI by hand: manually select the new GTI using some tasks (e.g., xmmlight_clean.csh, which removes counts using some tasks (e.g., xmmlight_clean.csh, which removes counts > 3 > 3 σσ from the mean until a stable solution is obtained) from the mean until a stable solution is obtained) using the “Baldi procedure”: CR[10-13 keV]<0.35 cps (pn) & using the “Baldi procedure”: CR[10-13 keV]<0.35 cps (pn) & CR[10-12.4 keV]<0.15 cps (MOS1, MOS2)CR[10-12.4 keV]<0.15 cps (MOS1, MOS2)

IV.IV. Verify that the high-background intervals have been removedVerify that the high-background intervals have been removed

V.V. Select the pattern (typically 0-4 for pn and 0-12 for MOS12), the Select the pattern (typically 0-4 for pn and 0-12 for MOS12), the energy range and the level of cleaning of the data (e.g., flag=0)energy range and the level of cleaning of the data (e.g., flag=0)

VI.VI. Create and display an image and check for the level of the backgroundCreate and display an image and check for the level of the background


Extraction of spectra in Extraction of spectra in XMM-Newton XMM-Newton EPIC EPIC

i.i. From the “clean” event file, create an image in the chosen energy range From the “clean” event file, create an image in the chosen energy range and select the source- and background-extraction regions, possibly in and select the source- and background-extraction regions, possibly in the same CCD chip the same CCD chip visualize the smoothed image in case of faint or visualize the smoothed image in case of faint or extended X-ray sources and optimize the source extraction radius in extended X-ray sources and optimize the source extraction radius in order to maximize the S/N ratio (task order to maximize the S/N ratio (task eregionalyse)eregionalyse) ii.ii. Run Run especget especget to extract the (source+background) spectrum, the backg. to extract the (source+background) spectrum, the backg. spectrum, the Redistribution Matrix File (RMF) and the Ancillary spectrum, the Redistribution Matrix File (RMF) and the Ancillary Response File (ARF), required for X-ray spectral analysis within XSPECResponse File (ARF), required for X-ray spectral analysis within XSPEC Required: source and background regions in physical coordinatesRequired: source and background regions in physical coordinates iii.iii. Rebin the data with N>15-20 counts per bin in order to apply the Rebin the data with N>15-20 counts per bin in order to apply the 22 statisticsstatistics

• Alternatively, use the Cash-statistics on the unbinned data if the numberAlternatively, use the Cash-statistics on the unbinned data if the number counts is low counts is low

An example of XMM-Newton image…

EPIC-pnEPIC-pn EPIC-MOSEPIC-MOS


…and spectrum

HEASARCHEASARC webpagewebpage

Past, present, and future X-ray/Past, present, and future X-ray/-ray missions-ray missionsArchives + Calibrations (CALDB files)Archives + Calibrations (CALDB files)SoftwareSoftwareToolsTools[…]

http://heasarc.gsfc.nasa.gov/



HEASARC archive toolHEASARC archive tool

amongamong the other tools… the other tools…

energy converter toolenergy converter tool

E=h

=hc/

h=6.662 10-27 cm2 g/s ; 1 keV=1.602 10-16 joule=1.602 10-9 erg=1.602 10-9 g cm2 /sec2

1 keV 12.3984

Å


Banda XRadio sub-mm Infrarosso ottico UV

Log Log ff

Log Log

IR peak due AGNIR peak due AGNreprocessed radiation by dustreprocessed radiation by dust

Utilizzo degli archivi e informazioni di base per l’analisi dei dati in banda X

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