Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xmm.vilspa.esa.es/external/xmm_links/trainee/alumni/a_martin.pdf Дата изменения: Wed Aug 16 16:16:38 2006 Дата индексирования: Sat Dec 22 14:34:20 2007 Кодировка: Поисковые слова: воздушные массы

XMM-Newton Timing Monitoring
Antonio Martin Carrillo Tutor: Marcus Kirsch
July 24, 2006

Antonio Martin Carrillo

1


Overview
XMM-Newton Pulsars Crab pulsar Relative time accuracy
2 epoch folding

Conclusions Next steps

Antonio Martin Carrillo

2


XMM-Newton
· Launched in December 1999 · 3 independent CCD cameras called EPIC (European Photon Imaging Camera) · 2MOS and 1PN · Several observing modes with different time resolution

Antonio Martin Carrillo

3


XMM-Newton
· We want to study objects with high spining velocities · We need a camera with a really good time resolution
Timing mode Burst mode

EPIC PN

Time Res: 0.03 ms

Time Res: 7 s

Antonio Martin Carrillo

4


Pulsars
· Neutron stars with high spining velocities and strong magnetic fields · Radius ~ 10 km · Density ~ 4x1014 gcm-3 · Temperature ~ 1010 K · Magnetic field ~ 109-12 G
Radiation beam Rotation axis Radiation beam

Antonio Martin Carrillo

5


Crab pulsar
· Discovered at 1968 in radio · The most studied pulsar in every wavelength · Very bright source with a stable pulse · Distance: 2200 pc · Period of 33 ms · Two observations per year with XMM-Newton: spring and autumn
Antonio Martin Carrillo 6


Relative time accuracy
· Procedure to obtain the relative time accuracy 1. 2. 3. 4. 5. 6. 7. Choose the correct EPIC PN mode Produce the event file Do the barycentric correction Extrapolate the radio data observation Epoch folding to one phase Search for the period in X-ray using 2 test Obtain the 2 plot, the X-ray period and the P/P

P PR - PX = P PR

Relative error
Antonio Martin Carrillo 7


Epoch folding
rate

+ +

time

phase
Antonio Martin Carrillo 8


Epoch folding
· Lightcurve of the Crab · Range between 0.5-10 keV · Pulse profile presents two maximums

Antonio Martin Carrillo

9


2 epoch folding
· Typical result of a 2 test for one observation of the Crab pulsar

SIGNAL

NOISE

Antonio Martin Carrillo

10


Relative time accuracy using Crab
· Representation of the relative error vs epoch (left) and observational time (right)

Antonio Martin Carrillo

11


Error approximation
· P=PR-PX error of our observation · Consider that the radio period has no error · The P comes from the error of the X-ray period · 2 distribution can be approximated by a triangle
TOB NPER + TOB P2 = NPER - P FWHM 2 P= 1 1 where NPER = TOB P 1 P2 -P 1 FWHM 2 TOB

P

1

P

0

P

2

· Approximation:

P =

FWHM 10 ?

· Compare the real and approximated errors of the periods
Antonio Martin Carrillo 12


Preliminary results
· Comparison of expectable relative error and real values for different pulsars

FWHM/10/P (FWHM=P2/T)

Antonio Martin Carrillo

13


Conclusions
· The relative time accuracy for the Crab with the new observations analysed is:

P < 3 в10 P

-8

· As shown in the previous plots, we can say that the relative error does not depends on the Earth's orbital phase.

Antonio Martin Carrillo

14


Next steps
· Monte Carlo simulation to produce the errors of the periods · Calibration of the factor for the expectable errors of the periods · Further analysis of other pulsars

Antonio Martin Carrillo

15