This document summarizes an analysis of X-ray data from the longest XMM-Newton observation of the galaxy ARK 564. The observation was 101,774 seconds in duration. Spectral analysis was performed using XSPEC software. The spectrum from 3-10 keV was initially fitted with an absorbed power law model. Adding a Gaussian component at 6.4 keV improved the fit, likely modeling iron K-alpha fluorescent emission. Below 3 keV, excess emission was observed indicating a soft X-ray excess from the source.

1. X-RAY DATA ANALYSIS OF THE LONGEST
EXPOSURE XMM-NEWTON OBSERVATION OF
ARK564
PROJECT REPORT
BY
SARANYA S NAIR
Under the guidance of
Dr.NINAN SAJEETH PHILIP
DEPARTMENT OF PHYSICS
ST.THOMAS COLLEGE,KOZHENCHERRY

2.  Astronomy is a natural science which is the study of
celestial objects(such as
stars,galaxies,planets,moons,and nebulae),the
physics,chemistry,and evolution of such subjects, and
phenomena that originate outside the atmosphere of
earth, including supernovae explosions, gamma ray
bursts, and cosmic microwave background radiation.
 Astronomy split into two:
Theoretical and Observational astronomy
INTRODUCTION

3.  Klilhelm Conrad Roentgen discovered X-rays.
 X-rays are a form of light, but much more energetic
than the light detected by our eyes.
 They are part of the electromagnetic spectrum.
X-ray and X-ray astronomy

4. • X-rays have a wavelength ranging from 0.01
to 10 nm
• X-rays are two types
• HARD X-RAY
• SOFT X-RAY

5.  X-ray astronomy is an observational branch of
astronomy, which deals with the study of X-ray
emission from celestial objects
 X-rays can knock off electron from matter. This
principle is used to build X-ray detectors
 . The first X-ray cosmic source was Scorpioces II.

6.  Spectroscopy is the study of the interaction between
matter and electromagnetic radiation.
 Basically one can observe two different classes of
spectra:
 CONTINUOUS and DISCRETE
Spectroscopy

7.  X-ray spectroscopy is a common analytical technique
with a wide range of applications.
 It includes the determination of crystal structure and
elemental analysis of solid samples
 Two types of X-ray spectroscopy:
Energy Dispersive X-ray Spectroscopy(EDS) &
Wavelength Dispersive X-ray Spectroscopy(WDS).
X-ray Spectroscopy

8. X-ray production mechanism
 Inverse Compton
Scattering
 Synchrotron radiation

9.  Bremsstrahlung radiation  Fluorescence

10.  An active galactic nucleus (AGN) is a compact region
at the centre of a galaxy which has a much higher
luminosity than other regions.
 EG: seyfort galaxies, Nuclei of radio galaxies, Quasars,
Blazers, BL Lac’s, LINER and N-galaxy
Active Galactic nucleus

11.  The X-ray spectrum of AGNs generally consists of a
primary power law continuum.
 The fluorescent emission line of iron k-alpha has been
observed at 6-7 keV
X-ray spectra of AGN

12.  Basic X-ray data usually comprise of lists of events which is
the event file.
 The fundamental counting relation between detected
counts in some detector unit and the source flux is
D (I) = T 𝑅 𝐼, 𝐸 𝐴 𝐸 𝐹 𝐸 𝑑𝐸 + 𝐵 𝐼
Where D (I) = observed no.of counts in the ithdetector
channel from source (+ background)
B (I) = Number of background units
F (E) = incident flux on the detector
R (I, E), A (I) = instrument dispense
X-ray data and data reduction

13.  Instrumentation methods typically measure the
position of the X-ray on the detector, the time of
arrival, and the energy of the photon.
 Data reduction is the process by which raw observed
data from a detector is cleaned and corrected for
instrumental effects.

14.  Forward fitting is the normal approach used to low or
modulate resolution X-ray spectral analysis.
 The most used measure for the “goodness” of a fit is
Pearson’s chi-square statistic- ᵡ2 - which measures the
variance of the residuals.
ᵡ2 = 𝑖=1
𝑁 𝐶 𝑖 −𝜇 𝑖
𝜎 𝑖
2
Spectral Analysis

15. Forward fitting

16.  XMM Newton and Chandra are two main
observatories in which x-ray telescopes present
facilitates the observation of sources.
Observatories

17.  Heasoft
 Science analysis software (SAS)
 XSPEC
Software for the X-ray data analysis

18.  Ark 564 was first identified as a Seyfert galaxy in 1976
 It is one of the brightest NLS1s in the X-ray band
 The X-ray spectra of NLS1s below 1-1.5 keV show a
prominent soft excess.
ARAKELIAN 564

19.  Observation details of Ark 564
OBSERVATION AND DATA
REDUCTION
Observed data set ID 0206400101
Ra 22:42:39.3
Dec +29:43:31
Time 2005-01-05
19:02:03
Duration 101774

20.  We reduced the data
using the SAS software.
 From the extracted
source and background
regions, light curve for
background and source
plus background is
obtained.
 Ark 564 observed by EPIC
pn small window mode

21. By subtracting the light curve
of the background region from
the light curve of source plus
background, we obtain the
actual light curve of the
source.

22.  We can obtain the spectrum of the source from the
extracted source and background region. Here also
the actual source spectrum is obtained by subtracting
background spectrum from the source (+
background) spectrum.
 The re binned spectra are analysed using XSPEC
version 12.8.2
SPECTRAL ANALYSIS

23. The analysis is started by
fitting the spectrum in the
energy band 3 – 10 keV
using the models power law
and wabs.
When using the model power
law, parameters Gamma and
norm are obtained. The values
are 2.38 and 1.12E-02 respectively.
Reduced chi-squared is 1.23 for
165 degrees of freedom.
 plot of data in the log scale in
the energy band 0.3-10 keV
 Normalised counts per second
per channel.

24. When wabs is used for modelling
the powerlaw parameters changed
to gamma~2.39 and norm~1.14E-02
and the reduced chi-squared
becomes 1.23 for 165 degrees of
freedom.
 spectrum fitted with Wabs and
Powerlaw from3.0 -10.0 keV
An improvement in fit
can be obtained by fitting the
spectrum with a zgauss model .
The model parameter values are
lineE ~6.4 keV, sigma ~0.3 keV
and norm ~1.21e-5 respectively.
And it gives rise to a reduced chi
squared of 1.05 for 162 degrees of
freedom. This shows that the
addition of zgauss has
significantly improved the fit.
 Spectrum in the energy band 3
- 10 keV fitted with wabs and
powerlaw and zgauss.

25.  Excess emission above the power law is found below
3 keV, which is the expected soft X-ray excess.
 Spectrum showing soft excess below 3keV

26.  We have produced both the light curve and the
spectrum of the source.
 The spectral analysis done with xspec showed a
powerlaw in the energy band 3-10 keV which we
modelled using powerlaw and wabs. On extrapolation
of the model down to 0.3 keV showed excess
emission above the observed powerlaw.
CONCLUSION

27. THANK YOU